# 01 Golf GTI 1.8t AWW - stuttering under acceleration



## nuftsu (May 18, 2010)

Car has 78k miles
I change the oil every 3000-3500 with mobile 1 synthetic

Lets get started on the things I have done trying to fix this problem.

replaced the sparkplugs
replaced fuel filter
replaced MAF ( bosch brand )
replaced thermostat
replaced coolant temp sensor

This problem is intermittent, it happens when the engine is cold or at running temp of 190f

when you accelerate around 2500-3200 rpms it seems like the engine stutters or like you would pop the clutch when learning to shift for the 1st time

I dont see the rpms drop when the stuttering happens, it can be reproduced under heavy throttle or just mild residential cruising throttle.

Sometimes my traction control light comes on like it has a problem or is disabled. I turned my car off and back on and the light turned off, I tried disabling the traction control with the button on my dash and the stuttering problem happens with it disabled.

Ive noticed when idling at stop lights sometimes the idle rpms will go from 800 down to 200 or almost stalling then just back up to 1200 then down to 800.

My father told me it seems like the fuel is running lean or possible throttle position sensor is burned out in certain spots

I have tried 3 ODBII readers on the car which all give me errors or link failures
I tried a offbrand vag-com reader(ebay special) which didnt work either.

I am either considering purchasing the real deal vag-com or taking it down to the VW dealer here but worried that they will tell me something crazy like I need a new ECU.


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## Turbo freak (May 9, 2005)

Check your fuel pressure under load. If your car is not chipped it must have 10 psi of boost, thus 55 psi (45psi+10psi) of fuel pressure under full boost. If low fuel pressure then change your fuel pump. If it is OK you better check/change your ignition coils.


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## ThatsGoodT (Jun 29, 2002)

Take a look at all of the PCV hoses for leaks/cracks. This picture I stole from another thread shows a common hose rupture. There are also some hoses that run under the intake manifold that can leak and cause some of the symptoms you're experiencing. My first thought was a bad MAF but since you've replaced it there may be something else going on. The ASR dash light blinking usually means the MAF. If you have an Autozone/Schucks/O'Rielly nearby they usually scan for free, might tell you if you've got a P0171 (too lean) code that is being stored and just not showing up as a CEL (or maybe you're getting a CEL, you didn't mention). Borrowing a VAGCOM (or buying one) is a good idea too because you can log certain measuring blocks to figure out if you're getting the right amount of airflow. Use this article to help understand what might be happening to your car: http://www.ross-tech.com/vag-com/cars/fuel-trim.html


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## ThaProwla (Nov 13, 2007)

sounds like you might have a transmission problem.... does the loss of power feel the clutch is slipping....or the engine dieing under a load?


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## rdwong (May 30, 2009)

OH MY 
I'm having the same issue. More or less.
Mine is chipped and running high power...
Last year I had many issues and changed:
All spark plugs
All ignition coils with hitachi ones
Map sensor (no maf sensor, running BOV, reprogramed ecu for that)
O2 sensor
Fan switch
Water pump.

This year I've went ahead with the coolant temperature sensor already. Just did it a few hours ago. Weirdly ran a little smoother, or maybe just in my head..... But STILL pops..... From other forums, sounds like fuel pump RELAY is another issue, and likely to have similar symptoms... BUT I went to the dealer and asked to buy one and he told me they rarely every go wrong, and he said 95% of the chance is its fine. Plus it makes sense that if it was starting to die, it wouldn't be just intermittently malfunctioning a little here and there..... 
I have a 2002 with the 1.8t that put out 180hp stock. 
I'm hopeing not, but another possibility is the fuel pump.... 
And I did a boost leak test. Fixed it up. Fuel filter is 10xxxkm old.......... Rather change that first to see than a fuel pump. I'm no good at diagnosing fuel related issues.... 

anyone got any ideas?


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## nuftsu (May 18, 2010)

I purchased 4 new ignition modules and during my install i saw the wires had cracks in them like i saw in some forums.. so I am going to retape for now.

I also saw there is a hose that is torn which im going to replace. the torn hose in the picture on this post is on the right side instead of the left like pictured.


While at work my father took the car to a mechanic who said their $7000 diag tool couldnt read any codes or make connection to the computer.. he then said it was my aftermarket stereo.. 

Ive had the stereo installed MONTHS before this issue... just to spite the guy I removed the aftermarket stereo still had the problem and installed the monsoon VW stereo back and still had the issues...


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## rdwong (May 30, 2009)

hey, how is your car now??
Mine is still stuttering...
I'm going to try replacing the fuel pump relay.... really not sure how or if it'll fix it.... but another forum and my instincts makes me suspicious. 
I've also noticed that in the morning and after work when engine is totally cold (starts fine every time when warm) that if I wait for the pump to prime and turn off, then start the car, it will stutter and stall. But the past 2 times I tried to start the car AS the pump is priming, i've been succesful.


MORE HELP!!!


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## iTech (Dec 29, 2008)

Thats funny your dealer said fuel pump relay's never go bad. I can remember literally hundreds of fuel pump relay issues caused in the early mk4 cars when I was at the dealer. They would also melt the relay panel when they fried. However fuel pump relays are also almost always accompanied by multiple short to ground faults in just about every sensor under the hood. That was usually the dead give away for them going out. Considering the amount of current they handle prolly not a bad idea to replace to save future issues but I doubt it will fix the issue.


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## iTech (Dec 29, 2008)

rdwong said:


> hey, how is your car now??
> Mine is still stuttering...
> I'm going to try replacing the fuel pump relay.... really not sure how or if it'll fix it.... but another forum and my instincts makes me suspicious.
> I've also noticed that in the morning and after work when engine is totally cold (starts fine every time when warm) that if I wait for the pump to prime and turn off, then start the car, it will stutter and stall. But the past 2 times I tried to start the car AS the pump is priming, i've been succesful.
> ...


Sounds as if your car may be losing fuel pressure as it sits. I would tap a fuel pressure gauge into the supply line and see if you lose pressure overnight. You should see at least 30psi of residual pressure still in the line in the morning. If it drops to zero check supply line in tank from pump to top of housing. The check valve for the system is located in the pump itself. If no leak found may be a bad pump.


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## rdwong (May 30, 2009)

iTech said:


> Sounds as if your car may be losing fuel pressure as it sits. I would tap a fuel pressure gauge into the supply line and see if you lose pressure overnight. You should see at least 30psi of residual pressure still in the line in the morning. If it drops to zero check supply line in tank from pump to top of housing. The check valve for the system is located in the pump itself. If no leak found may be a bad pump.


My car is modded btw.
First off... FIRST time I noticed something wasn't perfect was when my car stalled as I came to a stop sign and came to a near complete stop. ALL lights and power went out. and came back on nearly instantly after. Time reset itself to 12:00 and the millage recorder thingy went to 0.0km.... 
That was the only time it did that. I've paid real close attention afterwards and started noticing this.
It helps to have a full tank of gas btw....

Ok so I'll get a pressure guage tomorrow. How exactly does it work? 
And I have one of those walbro Fuel pump as well...
I AM pushing around 400whp.... So if ur gonna tell me that with 53000km which is ~ 30000miles? that I have pushed the other oem fuel pump too much, I'd believe it a little.... 
It would SUCKKKKK if i have a fuel leak or faulty pump........ and my lates fuel millage calculation 37L for 320km, city mainly + several full hard rips. So I'm getting decent fuel millage.

What would be the symptom if the fuel pump relay is JUST about to go bad?


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## rdwong (May 30, 2009)

oh and mine is the 2002 gti which came with the engine that made 180hp stock.... does that affect the fuel pump relay? or should I still change that?....


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## rdwong (May 30, 2009)

and what are the chances of fuel pressure regulators going bad....


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## nuftsu (May 18, 2010)

rdwong said:


> hey, how is your car now??
> Mine is still stuttering...
> I'm going to try replacing the fuel pump relay.... really not sure how or if it'll fix it.... but another forum and my instincts makes me suspicious.
> I've also noticed that in the morning and after work when engine is totally cold (starts fine every time when warm) that if I wait for the pump to prime and turn off, then start the car, it will stutter and stall. But the past 2 times I tried to start the car AS the pump is priming, i've been succesful.
> ...


The car is in the driveway, with multiple pieces taken off to get to the other end of this torn PCV hose, I got the wiring harness for the ignition modules taped very well, I took some 3m high temperature tape and wrapped the wiring for the modules before packing them back ontop of the engine near the exhaust pipe.

Im hoping this is the cause of all the problems... bad wiring, bad hose, or bad ignition modules... Im still trying to figure out if I want to try to test the fuel pressure or not. I still am uncomfortable that all the ODBII readers dont work and the mechanics reader didnt work.


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## rdwong (May 30, 2009)

I think its just that something is just giving its last breaths so it works well enough for the computer to not pickup much yet we notice it's coughs here and there...
let me know how yours go tomorrow. 
I'll be cancelling my gf's date to pull out my 3000km plugs and coils and recheck everything and maybe reclean intake air temp sensor and t/b as well... 
what are your guesses so far? I'm on the more fuel related issue.... but worth the effort making sure the ignition side of things are working right.

fuel pump relay? I still don't know.... I Wish it was that simple, but yet it just doesn't make sense, it starts every time. I mean well, first think in a cold morning it dies first time or twice, but then it'll start just fine after.
I AM getting more and more suspicious, although not wanting to, that it's the VW Main Intank fuel pump....... AHAHAHAH


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## rdwong (May 30, 2009)

Oh and I'm having a chat tomorrow with my buddy who's worked on dubbies for 20+ years.
I'll let you know what he thinks. 
But last time I asked him about a problem, and same thing about the time before, and the time before that....... his first answer is always the same. Go for a real hard ripp on the highway, all the way from 0 to 160, as hard as possible, and see how its acting. Kinda works. You get a better idea of what the issue is. Sometimes. Other times (twice now) the dying part just completely dies so you gotta call the tow truck. But at least you know whats wrong.... HAHA And those two times were the ignition coils. 
When i ripped it this time, it was simply more stutter....


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## HidRo (Sep 19, 2003)

Try to disconnect the N75 (you will run in limp mode) which will make you boost just 0.4 bar or something. Test to see. If it doesn't happen, test a good N75 on your car.


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## groggory (Apr 21, 2003)

> it starts every time. I mean well, first think in a cold morning it dies first time or twice, but then it'll start just fine after.


Sounds like a fuel pump on its way out and/or fuel filter clogged.


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## HidRo (Sep 19, 2003)

HUmmm, could also be a leak.


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## bass_4_ever (Dec 6, 2007)

chang your coilpacks


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## simon-says (Oct 21, 2007)

I'm seeing alot of these cars come into my shop. And the things I check are the grounds under the battery tray. Take them off and clean them. Then remove the PCV valve and check it. It must act like a check valve.(one way valve)
These cars are getting up there with mileage, and components are starting to wear out.


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## nuftsu (May 18, 2010)

Well new coil packs, which VW said they will reimburse me if my VIN is on the range of recalls for the modules... still didn't fix my problem.

$76 for a new PCV hose... 

on the good side.. after pulling my aftermarket stereo, which was hooked up with a adapter no splicing, I can get engine codes with the code readers now.

I get a 16487 code which 2 diff readers say " Mass or Volume Air Flow Circuit low - input "

I replaced this sensor about 1 1/2 years ago, I didn't pay $250 for it like most places want, I found it new on ebay for $50 and the part numbers match and it is a bosch. I know the part could have been cleaned to look new, but it looked new to me.

Im hoping there is a way to bypass this outrageously overpriced part which begins my searching on the interwebs for a solution.


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## rdwong (May 30, 2009)

Ok my car is heavily moddified. No maf sensor, its bypassed in reprogrammed ecu. No PCV, all piping is GOOD. Did boost leak test. Car has 53000km and the new Hitachi coil packs with new plugs are 5000km old approximately. Chevron 94 octane gas every time. Never ran tank dry.
And unplugging the N75 will make the car go in limp mode.... duh. :screwy: and if it doesn't then something is really wrong..... plus mine is aftermarket and crap, running 21 psi.... REALLY don't wanna mess with it unless i'm on a dyno.

......

Anymore ideas?


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## rdwong (May 30, 2009)

And I shampoo my engine every month..... does that make a difference??? It definetly means my engine bay is clean and ain't filled with gunk! and my hoses are NOT cracked anywhere.


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## rdwong (May 30, 2009)

I FIGURED MINE OUT!!!!!
They were my plugs.
got 7000km or so on them but went foul already. My previous plugs had 4000km or so and were in alright condition and were working fine before i pulled them out (only put new ones in to help diagnose a misfire which ended up to be my coils) so I threw them back in since it was real late at night, and been working like a charm since! 
I'll be heading to a shop to buy some brand new plugs and pull these used ones out.... duh


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## dococ (Feb 22, 2008)

After ruminating over this part throttle hesitation issue for several months (similar to your part throttle problem) I have found one thing that may explain it and possibly lead to a solution:
The N249 valve apparently is noted for these part throttle hesitation issues.
Some links to peruse:
http://s4wiki.com/wiki/N249 This one alludes to the part throttle effect of the N249

Some N249 Delete DIYs - Leave the N112 if you live where emissions are tested:
http://forums.vwvortex.com/showthread.php?4778865-Info-Delete-N249-Keep-N112&highlight=N249
http://forums.vwvortex.com/showthre...ng-the-N249-An-Easier-Approach&highlight=N249
http://uk-mkivs.net/forums/t/265883.aspx

Hope this helps - I'll probably try the N249 delete this weekend.


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## brandonparncutt (May 1, 2012)

*03 MKIV Jetta 1.8t with a speech impediment*

I had a similar issue with my jetta...I racked my brains (and wallet) for weeks trying to get this straightened out. Initially it was a stutter...first thing replaced...coil packs. Problem seemed to have went away for a week or two. Then it started again, this time I had a check engine light...code was P2181 (i.e. Engine Coolant Temperature sensor). I figured this was likely not the cause but I replaced it anyway. Light went away and my gas mileage improved significantly. Still no fix, of course. Then I bought new spark plugs and gapped them. Nothing. Then I bought a blowoff valve (bad move I later found out, although it was the one recommended by most: Forge 005) Shortly thereafter my car started stalling on me at cruising (80mph) speed on the highway. I'm thinking...fuel issue for sure. Replace the fuel filter...nothing. Now I'm dreading the purchase of a fuel pump. I disconnected the MAF one day just to see, and the problem went away for about a day (there was also a change in the weather at this time...it started raining heavily). Before the issue returned I purchased a new MAF as I thought I figured it out. Well, I didn't. Finally, I gave up and took it to a VW enthusiast garage in the area (which I should've done right away). Turns out it was a 2 dollar vacuum hose under the intake manifold area...not sure which one. I definitely didn't check that area for damaged hoses though. Stuttering solved. The stalling, however, became a bigger issue afterwards. On a tip for the mechanic I switched the blowoff valve for a splitter instead (Forge 007 I believe). Now the car runs beautifully. Problem solved. So I guess if anyone is experiencing this and not having any error codes (mine started off as a misfire which is why I replaced the coil packs right away), I would check every hose for damage first. Also, I'd like to note that when my car stuttered it also made a sound like it was dumping pressure into the atmosphere...and it wasn't coming from the blowoff valve...sounded more like the wastegate. I hope my insight into this helps someone.


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## Wolfpack2008rf (Jan 23, 2012)

ThatsGoodT said:


> Take a look at all of the PCV hoses for leaks/cracks. This picture I stole from another thread shows a common hose rupture. There are also some hoses that run under the intake manifold that can leak and cause some of the symptoms you're experiencing. My first thought was a bad MAF but since you've replaced it there may be something else going on. The ASR dash light blinking usually means the MAF. If you have an Autozone/Schucks/O'Rielly nearby they usually scan for free, might tell you if you've got a P0171 (too lean) code that is being stored and just not showing up as a CEL (or maybe you're getting a CEL, you didn't mention). Borrowing a VAGCOM (or buying one) is a good idea too because you can log certain measuring blocks to figure out if you're getting the right amount of airflow. Use this article to help understand what might be happening to your car: http://www.ross-tech.com/vag-com/cars/fuel-trim.html


 Im dying on the inside looking at the conditions of this engine......:banghead:


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## groggory (Apr 21, 2003)

Wolfpack2008rf said:


> Im dying on the inside looking at the conditions of this engine......:banghead:


 Why? That car just raced in the Dakar :thumbup:


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## Wolfpack2008rf (Jan 23, 2012)

groggory said:


> Why? That car just raced in the Dakar :thumbup:


 Nah looks like its been through a sand storm with a bit of Oil mixed, hints the broken hoses.


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