# warm idle misfire/stumble



## PCG (Dec 9, 2006)

Does the 2.0t FSI engine typically have a very light occasional misfire at warm idle? Or is it something I should have checked out? I'm at 700 miles now so I'm still learning the "normal" behaviors of my new car, so please don't flame me if this is simply normal for this engine.
It's not really audible, the tach doesn't move at all, but there's something there. I can feel through the seat more then anything else, just a light kick from time to time. Bringing the idle up to 1000 or so doesn't make it go away. There's no CEL resulting from it. I'm currently running Shell 93 octane.
I searched the forum and while it seems a cold rough idle isn't uncommon (something I don't have) there's nothing definitive that I found regarding a warm engine's "normal" behavior. More then a few people seemed to play around with different spark plugs with minimal results. Other then that I couldn't really dig anything up.
Thanks,
Pete


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## b00stin_02917 (Aug 11, 2006)

*Re: warm idle misfire/stumble (PCG)*

I get it also.. ive heard if you change the plugs it gets rid of it. Doesnt really bother me but im going to rack up some miles before i do them.


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## CtGTi77 (Dec 7, 2006)

*Re: warm idle misfire/stumble (b00stin_02917)*

i have it too. i just noticed it today. it becomes a tad more noticeable with a non-resonated 3" GHL TBE


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## EurodealerTX (Oct 16, 2006)

^ ^ ^ ^ 
What they said. I have APR 3" TB and my rough idle started then, but I also had the exhaust on only seven days after I drove the GLI off the dealer lot.
Colder plugs will typically fix it but if it's not broken or throwing a CEL, you should be safe to wait until 15 or 20k rolls over before swapping an otherwise completely healthy set of plugs.
My $0.02. Good news is these engines will throw a cel nearly ANYTIME something is not right, so your new 2.0L should run good and strong for many miles to come!
-Michael
Round Rock, TX


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## ssaffioti (Apr 9, 2006)

Not that I dont believe you, but why does a cooler plug solve this problem?


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## magilson (Apr 18, 2005)

*Re: (ssaffioti)*


_Quote, originally posted by *ssaffioti* »_Not that I dont believe you, but why does a cooler plug solve this problem?

The plug itself can remove some of the heat of combustion. A "colder" plug than stock can remove more of that heat. _If_ the misfires are caused by detonation due to the plug, then a colder range plug can help.
There have been some examples of bad injectors and/or lifter issues as well but are more isolated.
I'd like to see long term testimonies as to this fix because sometimes just putting in new plugs can help, not necissarily colder plugs.


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## CtGTi77 (Dec 7, 2006)

*Re: (magilson)*


_Quote, originally posted by *magilson* »_The plug itself can remove some of the heat of combustion. A "colder" plug than stock can remove more of that heat. _If_ the misfires are caused by detonation due to the plug, then a colder range plug can help.






























Wow....it is frustrating how much misinformation gets posted on this website as if it were fact. i truly feel bad for the less experienced enthusiasts who visit this site in order to obtain knowledge. 
The spark plug *DOES NOT* remove heat from the combustion chamber!!! a "hotter" spark plug has a very small about of ceramic coating exposed, and a smaller contact area with the metal in the plug, because the ceramic is used to absorb/dissipate heat, a "hotter" plug becomes PHYSICALLY hotter because the metal in the plug absorbs more heat from the combustion chamber. in a high performance engine, where higher cylinder pressure exists (like in a forced induction engine) the intake charge can be ignited by the heat of the plug before the piston has reached TDC (top dead center, the highest point in the engine stroke when the fuel/air should be ignited) this forces the piston down prematurely and is called detonation (or pinging)....it is bad for the engine. because of this, when cylinder pressure is increased (by either more boost, or no2, or a smaller combustion chamber/domed pistons) generally a colder plug is required to avoid detonation. a "colder" plug will have a significantly larger ceramic insert to insure that the metal of the plug does not absorb too much heat from the combustion chamber, therefore making it less likely for detonation to occur.
here's a great website to learn more about how engines work:
http://www.howstuffworks.com
PS: everyone needs to realize that people come to the "technical" forums for information. If you dont know what you're talking about...dont post information as if it were factual. Or if you insist on posting, at LEAST do some research first










_Modified by CtGTi77 at 8:27 PM 1-29-2007_


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## magilson (Apr 18, 2005)

*Re: (CtGTi77)*


_Quote, originally posted by *CtGTi77* »_





























Wow....it is frustrating how much misinformation gets posted on this website as if it were fact. i truly feel bad for the less experienced enthusiasts who visit this site in order to obtain knowledge. 
The spark plug *DOES NOT* remove heat from the combustion chamber!!! a "hotter" spark plug has a very small about of ceramic coating exposed, and a smaller contact area with the metal in the plug, because the ceramic is used to absorb/dissipate heat, a "hotter" plug becomes PHYSICALLY hotter because the metal in the plug absorbs more heat from the combustion chamber. in a high performance engine, where higher cylinder pressure exists (like in a forced induction engine) the intake charge can be ignited by the heat of the plug before the piston has reached TDC (top dead center, the highest point in the engine stroke when the fuel/air should be ignited) this forces the piston down prematurely and is called detonation (or pinging)....it is bad for the engine. because of this, when cylinder pressure is increased (by either more boost, or no2, or a smaller combustion chamber/domed pistons) generally a colder plug is required to avoid detonation. a "colder" plug will have a significantly larger ceramic insert to insure that the metal of the plug does not absorb too much heat from the combustion chamber, therefore making it less likely for detonation to occur.
here's a great website to learn more about how engines work:
http://www.howstuffworks.com
PS: everyone needs to realize that people come to the "technical" forums for information. If you dont know what you're talking about...dont post information as if it were factual. Or if you insist on posting, at LEAST do some research first









_Modified by CtGTi77 at 8:27 PM 1-29-2007_

Oh sorry, I was just getting my information from an actual spark plug manufacturer, rather than you.








http://www.ngksparkplugs.com/t...ry=US
but nice try. http://****************.com/smile/emthup.gif
If you'd like to argue semantics, I'd be happy to, but I'm sure you fully understand the law of conservation of energy.
Since the plug can't pick and choose how much energy it would like or dislike absorbing, lets just stick to reality rather than a website designed to dumb things down for the average Joe (howstuffworks). The reality is that the ceramic _does_ help insulate the plug from heat, but the plug is also designed to remove more heat to the block. Ceramic is a great insulator, but not that great. http://****************.com/smile/emthup.gif 
And since you don't quite have it figured out yet, I'll continue to provide you with more links to clarify your understanding.








http://www.centuryperformance.com/spark.asp
"Conversely, a "Cold" spark plug has a shorter insulator nose and absorbs more combustion chamber heat. This heat travels a shorter distance, and allows the plug to operate at a lower internal temperature. A colder heat range can be necessary when an engine is modified for performance, subjected to heavy loads, or it is run at high RPMs for significant periods of time. The higher cylinder pressures developed by high compression, large camshafts, blowers and nitrous oxide, not to mention the RPM ranges we run our engines at while racing, make colder plugs mandatory to eliminate plug overheating and engine damage. The colder type plug removes heat more quickly, and will reduce the chance of pre-ignition/detonation and burn-out of the firing end. (Engine temperatures can affect the spark plug's operating temperature, but not the spark plug's heat range). "


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## ssaffioti (Apr 9, 2006)

*Re: (CtGTi77)*


_Quote, originally posted by *CtGTi77* »_ ....generally a colder plug is required to avoid detonation. 

This is what I was thinking... I don't think the slight vibrations at idle are due to pre-ignition / detonation since the vehicle isn't under load or boost. 



_Modified by ssaffioti at 10:00 PM 1-29-2007_


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## magilson (Apr 18, 2005)

*Re: (ssaffioti)*


_Quote, originally posted by *ssaffioti* »_
This is what I was thinking... I don't think the slight vibrations at idle are due to pre-ignition / detonation since the vehicle isn't under load or boost. 

_Modified by ssaffioti at 10:00 PM 1-29-2007_

neither are necessary to produce pre-ignition.


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## EurodealerTX (Oct 16, 2006)

Can't we all just get along?


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## ssaffioti (Apr 9, 2006)

So the question becomes...
Is it the general consensus that the 2.0T warm idle stumble is due to pre-ignition??
In my car, the feeling is very slight, but noticable sometimes. The CEL never comes on or flashes, and I never notice any spark knock at any engine speed or load.


_Modified by ssaffioti at 7:05 AM 1-30-2007_


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## magilson (Apr 18, 2005)

*Re: (ssaffioti)*


_Quote, originally posted by *ssaffioti* »_So the question becomes...
Is it the general consensus that the 2.0T warm idle stumble is due to pre-ignition??
In my car, the feeling is very slight, but noticable sometimes. The CEL never comes on or flashes, and I never notice any spark knock at any engine speed or load.

_Modified by ssaffioti at 7:05 AM 1-30-2007_

more likely misfire. Could be gas, could be deposits on the plug, could be injectors, could be lifters.
Switch your gas, pull the plugs and inspect them. Take it past the dealer and see what they think. That or if it isn't too bad just deal with it. I get a little stumble from time to time but it's nothing to worry about (i feel).


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## ssaffioti (Apr 9, 2006)

*Re: (magilson)*

I'm definitely in the "Just Deal with it" column.... Seems like 70% of the time it's perfectly smooth and you cannot tell the engine is running, 25% of the time the vibration can be felt, but extremely slight, and 5% of the time it is more noticable but definitely not severe.
I e-mailed ECS Tuning and got this response:
*Original Message:*
Hello,
I noticed on the website that these spark plugs are recommended for the 2006 GLI / GTI:
*NGK Spark Plug (#BKR7EIX) -- One heat range colder than the factory plugs *
My car is completely stock. Should I still use this plug over the original heat range plugs? If so, why?
I’ve also read somewhere that the slight uneven idle / vibrations at idle common to the 2.0T when warm can be cured with a slightly cooler plug. Is this true, or are most users just experiencing a better idle because the plugs are brand new ??
*ECS Tuning Response:*
Hello,

The reason we have the one heat range colder is because people have requested them. I don't think they will cure the idle issues, like you said new plugs. We are currently sourcing OEM plugs for your application.

FWIW.... Stephen


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## Boostin 6sp (Mar 10, 2006)

my car has it also. i'm 99% sure it's a fuel problem. going to check the injectors whenever i get the chance but it's definitely not easy. they're below the intake manifold if u look


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## CtGTi77 (Dec 7, 2006)

*Re: (magilson)*


_Quote, originally posted by *magilson* »_Oh sorry, I was just getting my information from an actual spark plug manufacturer, rather than you.









actually, when you want objective, factual information the manufacturer is the LAST place you want to go.
now, before you attempt to argue with me further, go back to your first post. now read it. how can you argue that for someone who does not yet understand the engineering principles of the internal combustion chamber, your origional post would be misleading. your second post was great (with the exception of the NGK page that DRASTICALLY overestimates the purpose of their plugs, thus justifying the $20/each price tag.) and if you had posted a detailed explaination the first time i wouldnt have felt the need to clarify. i wasnt attacking your character, it's the simple fact that as someone who learned a decent chunk of what i know about cars on a forums like this, i know the frustration of "learning" something that i assume is fact, only to find out i was misinformed


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## magilson (Apr 18, 2005)

*Re: (CtGTi77)*


_Quote, originally posted by *CtGTi77* »_
actually, when you want objective, factual information the manufacturer is the LAST place you want to go.
now, before you attempt to argue with me further, go back to your first post. now read it. how can you argue that for someone who does not yet understand the engineering principles of the internal combustion chamber, your origional post would be misleading. your second post was great (with the exception of the NGK page that DRASTICALLY overestimates the purpose of their plugs, thus justifying the $20/each price tag.) and if you had posted a detailed explaination the first time i wouldnt have felt the need to clarify. i wasnt attacking your character, it's the simple fact that as someone who learned a decent chunk of what i know about cars on a forums like this, i know the frustration of "learning" something that i assume is fact, only to find out i was misinformed









There was nothing incorrect about my statement. The plug is in fact removing heat from the combustion chamber. It is not because the ceramic is absorbing the heat of combustion, but is in fact thermally isolating the plug from the head. More ceramic, less heat transfer, "hotter" plug. Less ceramic, more heat transfer, "colder" plug.
_Therefore_ if it were in fact detonation and the detonation was caused by a hot plug, then going one heat range colder than stock (or a colder plug) could help.
However we have moved on in the conversation since then.
Your explanation, however, is incorrect and is verifiably so by a simple google search. http://****************.com/smile/emthup.gif 
http://www.google.com/search?s...range
If you'd like to discuss this further, I could continue to explain it to you by PM since this is moving off topic slightly.


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## iThread (Sep 27, 2005)

Yeah guys really, it's a good debate and hopefully it won't turn personal.
But, can you start a new topic on the plug mechanics debate and whoever does it just post a link to it here?
Thanks!


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## ssaffioti (Apr 9, 2006)

*Re: (iThread)*

I think occasional slight idle vibration is common to the 2.0T because in every review of the A4 2.0T I've ever read, the car is criticized for engine vibration. Our transverse mounting may help but not eliminate the problem altogether. 
I think when it comes time to change the plugs, I will use the OEM heat range (as recommended by ECS Tuning) but will switch to NGK Iridium because of all the good reviews. 
Also, there have been two revisions already to the coils, with the newest having a 'G' designation. I may upgrade my coils at the same time.
I only have 10,000 miles so far so I won't be touching the plugs for a while. VW is aware of cold-start vibrations, acknowledging that they may even trigger the CEL (this hasn't happened to me, knock-on-wood). If it's a fuel issue, then a software update might be on the way which will replace the utterly useless TSB that currently addresses this issue.
Lets keep this thread positive! Keeping this thread relevant could be valuable in discovering what the cause is as time goes by.
Stephen


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## 2zzge (Aug 16, 2006)

*Re: warm idle misfire/stumble (PCG)*

something i've noticed both now and while the car was stock...if i push the clutch in, the misfire at idle changes. (less severe and less frequent)








its as if the slight load that the clutch/tranny imposes can influence how the car idles and thus how it misfires.
not that i think that, that has anything to do with why it misfires...i just find it interesting that it lessens the misfires.


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## bgriggs (Jul 28, 2006)

*Re: warm idle misfire/stumble (2zzge)*

I just switched my plugs out yesterday in the hope that they would resolve the rough idle issue. I am at 28k so I figured it wouldn't be a bad idea anyways. Put in the BKR7EIX and at times it even seems a little worse. I left work at luch today to be greeted by a CEL. I love my VW








I am now thinking that the coils may be at fault now. I have already had to replace one dead one. While changing the plugs, I noticed quite a bit of BAD rust on the coils. I dont think they are producing quite hot enough of a spark at idle, IMO.
Does anyone know if there are any aftermarket coils under development?


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## 2zzge (Aug 16, 2006)

*Re: warm idle misfire/stumble (bgriggs)*

i saw a post on here with aftermarket coils some time back. (couple weeks maybe?) they were from asia IIRC and were about $800 a pop.


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## bgriggs (Jul 28, 2006)

*Re: warm idle misfire/stumble (2zzge)*

Yea, no thank you.


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## OOOO-A3 (Jul 20, 2004)

*Re: (ssaffioti)*


_Quote, originally posted by *ssaffioti* »_Also, there have been two revisions already to the coils, with the newest having a 'G' designation. 

You mean 'C'. 07K 905 715 *C*


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## ssaffioti (Apr 9, 2006)

*Re: (OOOO-A3)*


_Quote, originally posted by *OOOO-A3* »_
You mean 'C'. 07K 905 715 *C*

oops! You are correct, sir


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## boaz (Feb 1, 2007)

*Re: (ssaffioti)*

my car also slightly shakes at idle. 1000miles. was told to switch my gas. probably refill in a few days.
i was told by a friend that this is normal though. after reading this thread..
its like 50/50 normal or somethings not right..sigh*


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## ssaffioti (Apr 9, 2006)

I was thinking about this..... It is easy to suspect the coils because of VW's history and also because there have been two revisions. 
But, if there was a coil problem, I think we would see it throughout the rev range. It's not like the intensity or the quality of the spark changes as the engine speed increases. I've noticed that just applying a little bit of throttle makes the problem go away.
Boostin mentioned the fuel system. Instead of a malfunction, is it possible that for emissions reasons, the engine is tuned to run very lean at idle? Maybe instead of crappy spark, it could use just a touch more fuel?
What can we do about that?? I wonder if the tuners can shed some light on this.



_Modified by ssaffioti at 7:59 PM 2-8-2007_


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## LeBlanc. (Jul 15, 2003)

*Re: (ssaffioti)*

Part of this apparent vibration is inherent in the design of a four cylinder engine. Balance shafts were created for a reason, but that doesn't mean
that they quell all of the vibrations... they don't.
My .02 is that if you are able to log misfires at idle, then you have a problem.
Otherwise, most four cylinder cars shimmy a little bit at ide.


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## aqn (Nov 20, 2001)

http://www.ngksparkplugs.com/t...ry=US
"_It's important to remember spark plugs do not create heat, they only
remove heat. The spark plug works as a heat exchanger by pulling
unwanted thermal energy away from the combustion chamber, and
transferring the heat to the engine's cooling system._"
With that kind of "information" spouted as the Gospel's own truth by an
"official" Web site, it's no wonder the world is full of no-spring
fart-canned chrome-wheeled be-spoilered LED-festooned montrosities,
driven by people who think _all_ those mods are highly functional!
Someone at NGK needs to learn how to write, or learn more physics.
"_The spark plug works as a heat exchanger by pulling unwanted thermal
energy away from the combustion chamber_"??!!
WTF?! Silly me! I woulda thought that the _entire_ combustion
chamber, being of metal and mostly surrounded by coolant, would do a
much better job of pulling unwanted thermal energy away from the
combustion chamber". I didn't know that one needs _spark plugs_
(ooh! aah!) to pull "unwanted thermal energy away from the combustion
chamber"?! Well, dip me in sh*t and call me stinky! Here I am,
thinking that the spark plug is there to, well, spark. How silly of me.








Seriously though, just because you read it on the Web, don't automatically
snooze your bullsh*t detector.
Oh, and while I'm at it, here's another gem:
http://www.centuryperformance.com/spark.asp
"_How a Spark Plug Works:
The basics of a spark plug is that it must perform two primary functions.
1. To Ignite the Air/Fuel mixture
2. To REMOVE the heat out of the combustion chamber_"
There's more of that "remove heat" crap again!!!
I glanced through the wikipedia entry for "spark plug", http://en.wikipedia.org/wiki/Spark_plug,
and it seems the most accurate and authoritative. No mentions of "remove heat
from the combustion chamber" there!











_Modified by aqn at 11:14 PM 2-8-2007_


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## ssaffioti (Apr 9, 2006)

Who supplies the coil to Volkswagen?? I read somewhere that the company is 'Eldor.' Can someone verify this?
If we can find out who the supplier is, I will try to e-mail them directly to get specs for each coil revision, to see what was changed.


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## CtGTi77 (Dec 7, 2006)

*Re: warm idle misfire/stumble (aqn)*


_Quote, originally posted by *aqn* »_
With that kind of "information" spouted as the Gospel's own truth by an
"official" Web site, it's no wonder the world is full of no-spring
fart-canned chrome-wheeled be-spoilered LED-festooned montrosities,
driven by people who think _all_ those mods are highly functional!
Someone at NGK needs to learn how to write, or learn more physics.

 
I AM VINDICATED























FINALLY, another informed texer!
Just to let everyone know what i mean.....

_Quote »_ *from wikipedia:* The temperature of the insulator responds to the thermal conditions it is exposed to in the combustion chamber but not vice versa. *If the tip of the spark plug is too hot it can cause pre-ignition leading to detonation/knocking and damage may occur. *If it is too cold, electrically conductive deposits may form on the insulator causing a loss of spark energy or the actual shorting-out of the spark current.
A spark plug is said to be "hot" if it is a better heat insulator, keeping more heat in the tip of the spark plug. A spark plug is said to be "cold" if it can conduct more heat out of the spark plug tip and lower the tip's temperature. Whether a spark plug is "hot" or "cold" is known as the heat range of the spark plug

and from my origional post:

_Quote, originally posted by *CtGTi77* »_The spark plug *DOES NOT* remove heat from the combustion chamber!!! a "hotter" spark plug has a very small about of ceramic coating exposed, and a smaller contact area with the metal in the plug, *because the ceramic is used to absorb/dissipate heat, a "hotter" plug becomes PHYSICALLY hotter because the metal in the plug absorbs more heat from the combustion chamber. in a high performance engine, where higher cylinder pressure exists (like in a forced induction engine) the intake charge can be ignited by the heat of the plug before the piston has reached TDC* (top dead center, the highest point in the engine stroke when the fuel/air should be ignited) this forces the piston down prematurely and is called detonation (or pinging)....it is bad for the engine.


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## PCG (Dec 9, 2006)

Filled up with Mobil instead of Shell V-power for the first time in my GTI's life yesterday (it's only at 1200 miles), and today I have a perfectly smooth warm idle for the first time ever. Could just be a coincidence, but I'll definitely be filling up with Mobil again next time I fuel up.
This discovery was offset by my MFD deciding to develop issues though. The idea of people tearing apart my perfectly rattle free car to replace the thing has me a little nervous...


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## magilson (Apr 18, 2005)

*Re: warm idle misfire/stumble (aqn)*


_Quote, originally posted by *aqn* »_http://www.ngksparkplugs.com/t...ry=US
"_It's important to remember spark plugs do not create heat, they only
remove heat. The spark plug works as a heat exchanger by pulling
unwanted thermal energy away from the combustion chamber, and
transferring the heat to the engine's cooling system._"
With that kind of "information" spouted as the Gospel's own truth by an
"official" Web site, it's no wonder the world is full of no-spring
fart-canned chrome-wheeled be-spoilered LED-festooned montrosities,
driven by people who think _all_ those mods are highly functional!
Someone at NGK needs to learn how to write, or learn more physics.
"_The spark plug works as a heat exchanger by pulling unwanted thermal
energy away from the combustion chamber_"??!!
WTF?! Silly me! I woulda thought that the _entire_ combustion
chamber, being of metal and mostly surrounded by coolant, would do a
much better job of pulling unwanted thermal energy away from the
combustion chamber". I didn't know that one needs _spark plugs_
(ooh! aah!) to pull "unwanted thermal energy away from the combustion
chamber"?! Well, dip me in sh*t and call me stinky! Here I am,
thinking that the spark plug is there to, well, spark. How silly of me.








Seriously though, just because you read it on the Web, don't automatically
snooze your bullsh*t detector.
Oh, and while I'm at it, here's another gem:
http://www.centuryperformance.com/spark.asp
"_How a Spark Plug Works:
The basics of a spark plug is that it must perform two primary functions.
1. To Ignite the Air/Fuel mixture
2. To REMOVE the heat out of the combustion chamber_"
There's more of that "remove heat" crap again!!!
I glanced through the wikipedia entry for "spark plug", http://en.wikipedia.org/wiki/Spark_plug,
and it seems the most accurate and authoritative. No mentions of "remove heat
from the combustion chamber" there!








_Modified by aqn at 11:14 PM 2-8-2007_








wow, okay... here we go...
Quoting directly from Corky Bell's book Maximum Boost:
"'Heat Range' means no more or less than how the features of the plug are configured *to conduct heat away from the electrode*." - Corky Bell's Maximum Boost: Designing, Testing, and Installing Turbocharger Systems.
and now from your precious wikipedia article (which by the way is written by your average joe, so in theory it could have been written by someone as dense as yourself)
"The operating temperature of a spark plug is the actual physical temperature at the tip of the spark plug within the running engine. This is determined by a number of factors, *but primarily the actual temperature within the combustion chamber*. There is no direct relationship between the actual operating temperature of the spark plug and spark voltage."
So to sum it up for you (I know you must have a difficult time with these concepts)
Heat range is a rating for how well a plug can remove heat from the tip.
The heat at the tip of the plug directly related to the temperature in the combustion chamber.
Good lord. Did you two meet up at an idiot conference and decide to join forces?







Of course you may be smarter than Corky Bell and Wikipedia.... But it sure doesn't appear that way.








Now lets put two and two together. First of all heat transfer at the cylinder walls does happen. However that has nothing to do with what we are talking about so please try to stay focused. We are talking about spark plugs. The tip of the plug should be nearly if not exactly the temperature of the combustion chamber in an ideal situation. Now if you have a hot plug it's because (and let me reiterate for the THIRD TIME) this is because you have more insulator, which means less heat transfer which is why it stays "hot". Now a colder plug will have less insulation, therefore it can transfer more heat and remain "colder".
I never claimed it removed all the heat, some of the heat, heat only made on tuesdays, heat made when you ask it nicely. It just removes heat. I never said the combustion chamber itself can't remove heat. I never said it would bring the combustion chamber to absolute zero, 200 degrees F, or any other specific number. It just removes heat.
Now lets take a look at your beloved wikipedia AGAIN:
"There is no direct relationship between the actual operating temperature of the spark plug and spark voltage."
So if (according to you) all the spark plug does is spark, WHAT DOES THE HEAT RANGE MEAN?
You have a flawed understanding of spark plugs and you make yourself look foolish by making childish comments about something it is apparent you do not fully grasp. http://****************.com/smile/emthup.gif


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## magilson (Apr 18, 2005)

*Re: warm idle misfire/stumble (CtGTi77)*


_Quote, originally posted by *CtGTi77* »_ 
I AM VINDICATED

















at best you are misguided.








Lets take another look...

_Quote, originally posted by *CtGTi77* »_The spark plug DOES NOT remove heat from the combustion chamber!!! a "hotter" spark plug has a very small about of ceramic coating exposed, and a smaller contact area with the metal in the plug, *because the ceramic is used to absorb/dissipate heat, a "hotter" plug becomes PHYSICALLY hotter because the metal in the plug absorbs more heat from the combustion chamber. in a high performance engine, where higher cylinder pressure exists (like in a forced induction engine) the intake charge can be ignited by the heat of the plug before the piston has reached TDC* (top dead center, the highest point in the engine stroke when the fuel/air should be ignited) this forces the piston down prematurely and is called detonation (or pinging)....it is bad for the engine.


"The metal absorbs the heat from the combustion chamber" (the metal meaning the metal tip of the spark plug is to what I am assuming you refer) I would agree with that, the plug _is_ absorbing heat from the combustion chamber.
Now, I assume you also are aware the heat must go somewhere. Correct? Now you falsely understand the ceramic to "absorb/dissipate" that energy. Well, thats pretty basic. In reality the ceramic serves as an insulator making the path to satisfying entropy which means everything wants to have the same energy as everything else around it (crudely). SO how is that satisfied? BY TRANSFERRING HEAT AWAY FROM THE TIP AND INTO THE REST OF THE PLUG, WHICH IN TURN IS IN CONTACT WITH THE HEAD.
Your simply understanding might leave the average reader thinking," Hmm, how can the plug work without melting if it just keeps absorbing heat energy from the combustion chamber without that heat energy going anywhere." To that I would reply,"I already explained it to him and he just doesn't get it."








I applaud your effort though! http://****************.com/smile/emthup.gif


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## aqn (Nov 20, 2001)

*Re: warm idle misfire/stumble (magilson)*


_Quote, originally posted by *magilson* »_[...]
In reality the ceramic serves as an insulator making the path to satisfying entropy which means everything wants to have the same energy as everything else around it (crudely). SO how is that satisfied? BY TRANSFERRING HEAT AWAY FROM THE TIP AND INTO THE REST OF THE PLUG, WHICH IN TURN IS IN CONTACT WITH THE HEAD.

Ah, but that's *not* what you said originally. You said, and I quote:
"_The plug itself can remove some of the heat of combustion. A "colder" plug than stock can remove more of that heat._"
You chose to quote from http://www.ngksparkplugs.com and http://www.centuryperformance.com to
back that up. Both of those Web sites explicitly say that spark plugs "REMOVE
_[sic]_ the heat out of the combustion chamber", which make your statement
of "_remove some of the heat of combustion_" sounds wrong, even though you
might have meant to say "..._remove some of the heat of combustion *from the
electrode*_".
Had you chosen to quote from Corky Bell instead of from those two Web sites,
i.e. the spark plug's construction conducts heat *away from electrode*,
and the plug's capacity to keep its electrode cool determines the plug's
"temperature", this would have been a different conversation entirely.
(Also note that Corky Bell's book, if your quote is accurate, does *not*
say anything along the line of "_The spark plug works as a heat exchanger by
pulling unwanted thermal energy away from the combustion chamber_", as
http://www.ngksparkplugs.com asserts.)

_Quote, originally posted by *magilson* »_
and now from your precious wikipedia article (which by the way is written by your average joe, so in theory it could have been written by *someone as dense* as yourself)
So to sum it up for you (*I know you must have a difficult time with these concepts*) [...]
Good lord. *Did you two meet up at an idiot conference and decide to join forces?*







Of course you may be smarter than Corky Bell and Wikipedia.... But it sure doesn't appear that way.








You have a *flawed understanding of spark plugs and you make yourself look foolish by making childish comments* about something it is apparent you do not fully grasp. http://****************.com/smile/emthup.gif 

_Ad hominem_ attacks solves nothing.



_Modified by aqn at 10:05 PM 2-13-2007_


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## magilson (Apr 18, 2005)

I'm glad we could agree I was correct.
Edit: Fair enough thread. Let me clarify:
A spark plug tip does not heat up from sparking (or at least it's negligible)
However, the tip of the spark plug does get hot.
The spark plug gets hot because of combustion.
A spark plug has a heat range that describes it's ability to remove heat.
The spark plug can either remove that heat by causing pre-ignition or by moving the heat into the head.
If the spark plug removes heat and it gets hot from combustion then it is removing heat from combustion.
The spark plug is removing that heat into the head.
And again I can clarify what the ceramic is doing in the plug. If the plug has more ceramic, it is thermally isolated from the head and cannot transfer as much heat. This would be a hot plug. If the plug has less ceramic it is capable of more heat transfer and will be a colder plug.
I'm not sure how many more ways or additional times I will need to repeat this. I would like to be able to stop.
This is what I started saying. This is what I have continued to say.
I have had this questioned by two individuals who began each of their counterarguments with rude comments. I continued to present evidence. They continued to be rude. I returned in favor (which wasn't necessary but felt good).










_Modified by magilson at 10:28 PM 2-13-2007_


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## iThread (Sep 27, 2005)

This is a good informative topic, let's not ruin it with seething contempt for one another.


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## magilson (Apr 18, 2005)

*Re: warm idle misfire/stumble (aqn)*


_Quote, originally posted by *aqn* »_(Also note that Corky Bell's book, if your quote is accurate, does *not*
say anything along the line of "_The spark plug works as a heat exchanger by
pulling unwanted thermal energy away from the combustion chamber_", as
http://www.ngksparkplugs.com asserts.)

Because it had nothing to do with what he was trying to explain to the user. There are quite a few things he "leaves out" that are not necessary to convey the point.


_Quote, originally posted by *aqn* »__Ad hominem_ attacks solves nothing.

I agree and it would have been better had you and Ct not started out that way http://****************.com/smile/emthup.gif


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## 2zzge (Aug 16, 2006)

*Re: (iThread)*

Ralph: [whispering] Lisa, what's the answer to number seven?
Lisa: [whispering] Sorry, Ralph. That would defeat the purpose of testing as a means of student evaluation.
Ralph: [pauses] My cat's name is Mittens.








_It's important to remember spark plugs do not create heat, they only remove heat. The spark plug works as a heat exchanger_
from NGK's website
_It is important to understand that spark plugs CANNOT create heat, only remove it! _
from some performance airplane website
finally from a 30 year old mag
_The worst, most destructive, combination of mistakes we see begin with two widely-held assumptions: first, that a cold spark plug will help fend off that old devil detonation; second, that more spark advance -not less- is the thing to try when reaching for power. Try to use a too-cold spark plug and you very likely will have to jet for a lean mixture to avoid plug fouling - and as you lean an engine's air/fuel mixture down near the roughly-14.5:1 chemically-correct level it becomes extremely detonation-prone. Excessive spark advance is even worse in its ability to produce detonation, and when combined with a lean mixture it's enough to quickly destroy an engine. 
Most people who've had some experience with racing bikes (especially those with two-stroke engines) know that detonation is a piston-killer. Few really know the phenomenon for what it is: a too-sudden ending to the normal combustion process. You may imagine that the ignition spark causes an engine's mixture to explode, but it actually burns. There's a small bubble of flame formed at the spark gap when ignition occurs, and this bubble expands - its surface made a bit ragged by combustion chamber turbulence - until all the mixture is burning. This process begins slowly, but quickly gathers speed because the mixture beyond the flame_ bubble is being heated by compression and radiation to temperatures ever nearer the fuel's ignition point. When the initial spark is correctly timed the spreading flame bubble will have almost completely filled the combustion chamber as the piston reaches top center, and all burning will have been completed by the time the piston has moved just a millimeter or two into the power stroke. But the final phase of this process can be shifted from simple burning into a violent detonation of the last fraction of the whole mixture charge. 
Starting the fire too early will produce detonation, as it gives the mixture out in the chamber's far corners time enough to reach explosion-level temperature. And a slightly lean mixture detonates at a lower temperature. It's all a function of ignition timing and mixture in any given engine, and spark plug heat range plays absolutely no part in it.
Your engine's spark plug doesn't cause detonation but it can tell you when and why the phenomenon has occurred._
http://www.strappe.com/plugs.html


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## magilson (Apr 18, 2005)

*Re: (2zzge)*


_Quote, originally posted by *2zzge* »_...
Starting the fire too early will produce detonation, as it gives the mixture out in the chamber's far corners time enough to reach explosion-level temperature. And a slightly lean mixture detonates at a lower temperature. It's all a function of ignition timing and mixture in any given engine, and spark plug heat range plays absolutely no part in it.
Your engine's spark plug doesn't cause detonation but it can tell you when and why the phenomenon has occurred.
http://www.strappe.com/plugs.html









Hmm. A lot has changed in 30 years and there a lot of people who say otherwise. I'll have to do some more reading.
Here's my thought. Crank your K03 to 20 PSI. You get more air with heat. Do this to three motors. In the first, leave factory plugs. In the second use the same plug but one heat range cooler, in the third one heat range hotter. Which one will will be more prone to knock? Why?
I gotta believe it will correlate to the plug heat range. If there is no correlation then why are there different heat range plugs? Have we all been duped by marketing? Is the whole reason for hotter or colder plugs just to keep the plug clean?
From Edelbrock:
http://www.edelbrock.com/autom....html
"In other words, once the correct heat range is found that prevents fouling and does not contribute to the pre-ignition or detonation, a change to a hotter or colder plug will not have a positive effect on engine performance."
Thoughts?


_Modified by magilson at 11:18 PM 2-13-2007_


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## 2zzge (Aug 16, 2006)

*Re: (magilson)*

i think there's a dynamic here that not only includes the _efficient_ exchange of heat away from the tip of the plug but also the speed of the piston during combustion, combustion pressures, combustion chamber shape (piston and head), air/fuel mix, type of fuel and etc.
i do believe that the sparkplug reveals a 'bad' fuel/air mix or 'poor' timing by detonation...it doesn't cause it but, it is revealed thru it.
thusly can be made worse or better by changing the 'heat range' on the plug. 
but that isn't fixing the problem in reality. its like taking an asprinn for a hangover. it doesn't cure the hangover but does help with the headache. 
if a plug is heating up too much or staying hot too long it very well and most likey is a symptom of something else that is amiss....and more than likely the A/F mix and/or timing is off.
our 2.0t engine does not have the average combustion chamber nor does it use the average fuel/air mix (emissions/power) and etc. the dynamics involved are obviously more complex on this motor and seemingly more sensitive to slight changes because of it.
i too am going to have to do some more studying


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## magilson (Apr 18, 2005)

so the plug becomes a band-aid for a problem like excessive heat in the intake charge or too aggressive of timing advance. I can see what you mean.
Thing is, if you can get away with the colder plug, then why not? ( Assuming your not cooking your turbo, etc...)


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## 2zzge (Aug 16, 2006)

*Re: (magilson)*

i think that's what most of us do. the least consequence is having to buy plugs sooner than planned. which most of us are ready to do.
the worst is that the 'band-aid' doesn't stop the bleeding and we toast our turbo or burn our piston.
in reality we aren't getting the most out of our motor this way. if there's detonation occuring, we need to retune. if changing the octane works then fine. its an easy and fast fix that usually works for those ever-changing weather conditions. 
a step up or down on a plug is one of the last things we should try. its simple enough to do that we should actually be trying to find out why the plug is fouling or burning....or better stated, why is the combustion chamber too hot or too cold (instead of the asking why the plug is too hot or cold)


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## magilson (Apr 18, 2005)

*Re: (2zzge)*


_Quote, originally posted by *2zzge* »_...a step up or down on a plug is one of the last things we should try. its simple enough to do that...

But it's sooooo much cheaper than an intercooler or turbo to just buy four colder plugs


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## 2zzge (Aug 16, 2006)

*Re: (magilson)*

i know huh! well it seems that way anyway.
$50 a year for plugs vs $1000 for an intercooler? plugs win.
reducing engine ping/knock with 'cooler' plugs vs cooling the intake charge, reducing ping/knock and gaining HP _and_ not having to change the plugs? 
you tell me.


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## ssaffioti (Apr 9, 2006)

*Re: (2zzge)*


_Quote, originally posted by *2zzge* »_in reality we aren't getting the most out of our motor this way. if there's detonation occuring, we need to retune. 

I suspect (or wish) VW would release a software patch to fix this issue. They've definitely gotten compaints from owners who have misfires / shaking when cold -- hence the TSB that says "It's Normal"







Isn't it a possibility that the cold-start misfires and the warm idle misfires are caused by the same issue (bad tune)? Perhaps when VW owns up and fixes the cold-start problem, the warm-idle problem will be gone as well.


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## 2zzge (Aug 16, 2006)

*Re: (ssaffioti)*

this is one of the reasons 'we' need to keep up on how this motor is actually designed...to better understand how to tune it. if VW isn't going to, we'll need to.
besides, the more we know and understand, the better we can spend our money and time making performance mods http://****************.com/smile/emthup.gif no more wasting precious, hard-earned doe on temp fixes (plug changes) when the 'real' fix has got to be right in front of us.
keep up the good fight!


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## Captain Jack (Mar 2, 2002)

*Re: (ssaffioti)*


_Quote, originally posted by *ssaffioti* »_
I suspect (or wish) VW would release a software patch to fix this issue. They've definitely gotten compaints from owners who have misfires / shaking when cold -- hence the TSB that says "It's Normal"







Isn't it a possibility that the cold-start misfires and the warm idle misfires are caused by the same issue (bad tune)? Perhaps when VW owns up and fixes the cold-start problem, the warm-idle problem will be gone as well.

Its not the case of a bad tune. Ive now seen stock, giac and revo cars all with this issue. Theres something else that needs to be looked it. 
One of the most common causes for a jumpy idle is a leak somewhere in the system.


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## magilson (Apr 18, 2005)

*Re: (Captain Jack)*

I've talked to several people who have fixed the issue with coil pack replacement.


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## Captain Jack (Mar 2, 2002)

*Re: (magilson)*


_Quote, originally posted by *magilson* »_I've talked to several people who have fixed the issue with coil pack replacement.

Here we go again


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## manyDUBs (Dec 26, 2002)

*Re: (Captain Jack)*

So has any progress been made here other than 2 ppl using there knowledge to compete with one another or have they resolved the issue?
Thanks


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## observer (Mar 24, 2004)

*Re: (manyDUBs)*

Also have misfires at idle on cyl 2. As mentioned it goes away when you drive the car and VAG shows no misfires.
I also had a lean at idle code and and EVAP incorrect flow code and the car has been down on power lately. Heard people saying the I need to change the EVAP purge valve but I don't want to do it if it is not the problem. Changed to the latest c valve and the problem is still there.
Also suspect a leak of some sort,


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## Cp1024 (Mar 2, 2018)

Ive run into something that could be related. Ive noticed when mt engine is cold or at NOT it runs like a top, but if engine is started warm like 100°F to 180°F it has random misfires with lean at idle. I suspect pcv valve because of oil leak at crankshaft. But wonder if there is an intake component stuck or vapor in the fuel line. Since there was a TSB for fuel pump pressure anybody else seeing this?


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