# Random Misfire; new plugs and wires



## Daddioman (Apr 19, 2007)

I thought the new wires and spark plugs fixed my misfiring. Ran great for a few days, then got the sputtering back caused the service light to blink. Only drive 7.5 miles a day to work. some days no problem. Out of nowhere it sputters, Rev it up a little then it goes away. Auto zone read error codes "Random misfire; cylinders 2, 5, 4." Gonna pull a plug and see if its fouling. Got highly recommended Bosch plugs and $200 wires.


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## spitpilot (Feb 14, 2000)

*Re: Random Misfire; new plugs and wires (Daddioman)*

I'd stick with OEM NGK plugs! BKR6EKUB...VW engineers spend lots of time and $$$ testing to match plugs to engine....all claims from plug mfgrs not backed up with test data on your specific engine..are just marketing BS!....Another cause of misfires after plug change is damage to insulator..if plug socket slips off you can crack insulator..or getting some antisieze compound on the insulator..either of these will cause bad misfires when things are damp..getting better as engine heats up..so your misfires come and go....


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## Peter Badore (Jun 17, 2002)

*Re: Random Misfire; new plugs and wires (spitpilot)*

2nd this. Put in the factory specified NGK spark plugs and be careful not to damage the wire connectors.


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## Daddioman (Apr 19, 2007)

*Re: Random Misfire; new plugs and wires (Peter Badore)*

OK Fellas, I really believe I installed my wires and plugs without damaging them. And lets just say the guys from German Auto in Grand Rapids MI that told me (and sold) me Bosch FR7LDC spark plugs cause thats what they would use. (and I didn't want to pay the little bit more for NGK plugs cause I hate the dealer rapists) lets just say these are to spec. My car ran like a dream for about a week. Then the random firing began, first intermittently, yesterday it was pretty much non-stop on my short ride 7.5m from work - so it's staying in my garage now. I pulled out plug number 2 and it's carboned up with soot. Lets just say its not the plug type and the wires are good. What would be the first thing to check, Whats fouling out these plugs ?


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## uglybaby (Mar 19, 2006)

soot usually means running rich right? O2 sensor maybe?


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## Peter Badore (Jun 17, 2002)

*Re: (uglybaby)*

Do you have a current VAG-COM scan?


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## uglybaby (Mar 19, 2006)

original coil pack?


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## Daddioman (Apr 19, 2007)

*Re: (uglybaby)*

My Audi has been sitting in my garage for a month.
I got some NGK BKR6EGP plugs and very carefully replaced them.
Started engine and it felt like only four cylinders were firing. 
I don;t understand why I can not remove these brand new wires from the ignition coil, they will not come back out. I have used quite a lot of force to get them off and they won't budge.
I replaced the ignition coil just last summer. so its not original. didn't have any problem pulling the old wires off or putting them on.
Not sure the new wires had the same ignition coil ends, but the plug ends are close or arelike original wires.
Haven't changed coil pack.
I've been driving this car for 10,000 miles with bad catalytic converters.
Now i'm wondering if that caused more problems, or what was it that made them fail 
on ignition coil

I don't know what a VAG-COM scan ?


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## DopeAudi (Jan 18, 2010)

*Re: Random Misfire; new plugs and wires (Daddioman)*

it could be your injectors


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## Daddioman (Apr 19, 2007)

*Re: Have codes, before I changed wires - what do I change now ?*

Replaced Wires and Plugs, Car ran good for 2 days, but now starts up OK but not running good enough to drive. Found List of codes/ faults found when "German Auto" shop suggested I start with changing wires, I should have let them change the wires, didn't realize until now it had all these faults: (before I changed wites) What should I change next ?
(19) faults:
18010 - Power Supply Terminal 30: Voltage too Low 
P1602 - 35 -10 - - - Intermittent
16806 - Main Catalyst Bank 1: Efficiency Below Threashold 
P0422 -35-00
16816 -Main Catalyst Bank 2: Efficiency Below Threashold 
P0432 -35-00
16684 - Random/Multiple Cylinder Misfire Detected P0300 - 35-00
16684 - Random/Multiple Cylinder Misfire Detected P0300 - 35-10 Intermittent
16687 - Cylinder 3: Misfire Detected P0303 -35-10 --- intermittent
16687 - Cylinder 3: Misfire Detected P0303 -35-10 ---
16686 - Cylinder 2: Misfire Detected P0302 -35-10 --- intermittent
17544 - Fuel Trim: Bank 1 (add) System too Lean P1138 - 35-00
17546 - Fuel Trim: Bank 2 (add) System too Lean P1138 - 35-10
16688 - Cylinder 4: Misfire Detected P0304 -35-00 ---
16686 - Cylinder 2: Misfire Detected P0302 -35-00 ---
16825 - EVAP Emission Control Sys: Incorrect Flow P0441 - 35-00
16688 - Cylinder 4: Misfire Detected P0304 -35-10 --- intermittent
16685 - Cylinder 1: Misfire Detected P0301 -35-00
16690 - Cylinder 6: Misfire Detected P0306 -35-00
16685 - Cylinder 1: Misfire Detected P0301 -35-10 --- intermittent
16690 - Cylinder 6: Misfire Detected P0306 -35-10 --- intermittent
16839 - EVAP System: Large Leak detected P0455 - 35-00


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## O_o (Nov 12, 2009)

*FV-QR*

Some of those codes could be old. Clear them and see what comes back.


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## Daddioman (Apr 19, 2007)

*Re: FV-QR ()*

I took it in for service cause it was occasionally sputtering, but running fairly well otherwise. They cleared the codes and ran a diagnostics and got listed codes. They wanted over $400 to change wires and plugs as first step to fix faults. I decided I would change wiresplugs myself. Did that ran good for coupla days no missing. Then started to do it again. I rechecked my wiring and plugs - now it runs misses so bad I can not drive it. So do these codes indicate what I might check or part change out - otherwise I need to tow it and I don't trust any nearby service stations.


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## O_o (Nov 12, 2009)

*Re: Have codes, before I changed wires - what do I change now ? (Daddioman)*


_Quote, originally posted by *Daddioman* »_18010 - Power Supply Terminal 30: Voltage too Low

Check the voltage at the regulator. You might need a new alternator/V-reg.
The rest, individually, could be caused by dozens of different things. The one thing they have in common though is that they can all be caused by a vacuum leak. That's where I'd start.


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## Daddioman (Apr 19, 2007)

Thank you


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## 2001 Variant (May 27, 2007)

*Re: (Daddioman)*

Yeah a vac leak sounds likely.
I would say fouled plugs are the main reason why it's not running well right now but they are not the root cause of your issues. You're either running too rich causing the half burned fuel to deposit on the plugs or your ignition system is not working right causing the fouling.
Or (and this wouldn't be fun) you are getting oil in the cylinders which burns and fouls the plugs (but it's unlikely this would happen to more than one or two cylinders at once).
As long as the plugs are the right spec it shouldn't matter if they are Bosch or NGK. Sure, NGK might be better but the Bosch should not be causing this kind of trouble. However, if they are not the right spec they might be running too cold which could keep them from burning off carbon deposits. But I doubt this would show after this little time and you were having issues before as well.
I would remove the plugs, clean them thoroughly with a brass wire brush reinstall them. You'll likely see improvement in idling and such. Then you can troubleshoot where the real issue is coming from. You don't need to buy new plugs just because they have some deposit on them from running rich for a week. Reset the codes. Now you can troubleshoot without having the symptoms skew your diagnosis.
Check the ignition coils and their ground/supply lines, check the battery/alternator and check for vacuum leaks. If you've never replaced your vac lines it's a good idea to do so (and it's cheap).


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## Daddioman (Apr 19, 2007)

Thank you, appreciate your time spent. Do you know where there might be instructions on replacing those vacuum lines - I could throw down and get the Chiltons book if it gives good detail on that. Maybe it's obvious / simple if I buy the hoses. I also can talk to shop that ran my codes - sometimes they're cooperative


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## Ktftj07 (Mar 20, 2007)

*Re: (Daddioman)*

i had this same issue.... sputtering, blinking check engine light. I did new plugs n wires, o2, air sensor... nothing... 
then i got a new coil from advance auto parts, and now it runs like a champ!!! good luck


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## O_o (Nov 12, 2009)

*Re: (Daddioman)*

A VW dealer should have a vacuum line kit. It's fairly obvious where things go, unless one of the old lines has popped off and you don't know where it came from, which sounds probable, since you appear to have a large leak. I'll see if I can find a vacuum diagram for you.


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## O_o (Nov 12, 2009)

*Re: (Ktftj07)*

As it turns out, there is a recent topic on this:


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## Daddioman (Apr 19, 2007)

*Re: ()*

Thanks I appreciate your help. I'll buy the kit and check around for info, if it's not obvious where it goes. I can do it, but i get a little intimidated sometimes - afraid i'll break something else. I did a quick look last night around the engine didn't see any loose hoses. But I replaced that other plastic contaption that goes around the top and into the valve covers about a year ago. It was so brittle - the hoses probably are suffering the same aging problem. Actually I tried to do that myself - but took it in and paid to have it done.


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## 2001 Variant (May 27, 2007)

*Re: (Daddioman)*

You don't have to buy the kit from VW (although it's probably not too expensive). You can just go to your favorite auto parts store and buy 3.5 mm inner diameter silicone vacuum hose by the foot. You'll need about 8 or so and it should be around $1.5 per foot. They might refer to it as fuel line.
You won't see much of it under the hood until you take the engine cover off. Just take a big screwdriver and push and turn the screws. They aren't real screws, just banjo style plugs that will come lose with a slight turn.
Just take a good look at the the rats nest of vac hoses on top of the engine (maybe take a digital pic to improve your memory) and replace each piece one by one.


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## Slimjimmn (Apr 8, 2006)

*Re: (2001 Variant)*

just to let you know, if the catalytic converter has a hole in it from misfiring or just due to age, it will cause a loss of backpressure and your car will run like crap. On the other hand if the cat melted do to overheating it would cause poor performance and lack of power also.


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## O_o (Nov 12, 2009)

*Re: (2001 Variant)*


_Quote, originally posted by *2001 Variant* »_You don't have to buy the kit from VW (although it's probably not too expensive). You can just go to your favorite auto parts store and buy 3.5 mm inner diameter silicone vacuum hose by the foot. You'll need about 8 or so and it should be around $1.5 per foot.

True, but aren't some of the lines 5mm? Also, I think the kit comes with the hoses already cut to length, and with all the tees & fittings, at least one of which will almost certainly be cracked...


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## Daddioman (Apr 19, 2007)

*Re: ()*

I started the car up, for the first time in 6 weeks, to see if I could hear a vacuum line leak. It started right up but still sounds like its running on 5 cylinders. I have the engines covers off and heard no hissing, wiggled wires and looked around at what look like the vaccum line and see no faults. Didn't run it very long for fear of causing damage. The comment of my root cause being the cats -i don't like the fault of. I have found no one that can replace these for less than $1K. Tomorrow I will pull the plugs and clean them up as suggested.
I don't except a fix with that, because my last try was putting all new plugs in and there was no improvement. When replacing plugs thats when i noticed no 2 plug was especially sooted - so like you previously stated the fouling of the plug may the root of my problem. Would i be foolish to drive 10 miles at 35mph on 5 cylinders to the service station ?


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## tryin2vw (Dec 30, 2006)

*Re: (Daddioman)*

Have you tried a compression test, both dry and wet? How do the numbers look, specifically on #2 cylinder?
Fixed the spelling


_Modified by tryin2vw at 5:17 AM 2-27-2010_


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## O_o (Nov 12, 2009)

*Re: (tryin2vw)*

Have you checked the voltage output at the alternator yet? Unless the battery was dead or disconnected, this is the only reason I can think of for it to throw 18010. If the alternator's weak, or the voltage regulator is shot, you will have a weak spark and random misfires.

_Quote, originally posted by *Daddioman* »_Would i be foolish to drive 10 miles at 35mph on 5 cylinders to the service station ? 

It's hard to say without actually knowing what's wrong. It would definitely be foolish to do so without a friend following in their car...


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## Slimjimmn (Apr 8, 2006)

*Re: ()*

a compression check would tell if its a mechanical problem or electrical problem.


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## volvoguy27 (Dec 21, 2005)

*Re: (2001 Variant)*


_Quote, originally posted by *2001 Variant* »_As long as the plugs are the right spec it shouldn't matter if they are Bosch or NGK. Sure, NGK might be better but the Bosch should not be causing this kind of trouble. .

Put a set of Bosch plugs in a Volvo with Coil on Plug and see how long it runs good. 
On a side note, a bad MAF could cause a rich condition too.


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