# Cylinder 4 misfire woes



## vwlippy (Jul 17, 2001)

So annoying.... I have a cylinder 4 misfire again. My coils and plugs are all fairly new, so who knows. Anyone have a cyliinder misfire and it NOT be a coil or plug? 

I swapped the Cylinder 4 coilpack with the Cylinder 1 coilpack, so we'll see if the code switches to Cylinder 1.


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## caudex (Oct 7, 2002)

EXACT same problem here. I'd love to know the reason for this.
My idle is also rough when the motor is cold. It only lasts for about a minute but its still annoying.
I've also put in brand new coil packs and plugs.


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## vwlippy (Jul 17, 2001)

Yeah... mine kinda runs a little rough when cold too.


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## Uber-A3 (Feb 23, 2002)

vwlippy said:


> Yeah... mine kinda runs a little rough when cold too.


If the problem stays on cylinder 4 time to swap injectors.


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## tiptronic (Apr 18, 1999)

vwlippy said:


> So annoying.... I have a cylinder 4 misfire again. My coils and plugs are all fairly new, so who knows. Anyone have a cyliinder misfire and it NOT be a coil or plug?
> 
> I swapped the Cylinder 4 coilpack with the Cylinder 1 coilpack, so we'll see if the code switches to Cylinder 1.


May I ask how many miles do you guys have? Any Mods? Why are these coilpack issue still in existance! I thought they've figured this all out on previous 1.8t engines. 

e


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## vwlippy (Jul 17, 2001)

I have 73k miles. No engine mods except for a K&N filter. 
I just had the coilpacks replaced for free because of the recall a few months ago. 
So frustrating.


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## caudex (Oct 7, 2002)

I have 83k and the only mod I have is a Neuspeed intake. Is there anyway to confirm that this is an injector problem?


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## Guest (Sep 30, 2010)

caudex said:


> EXACT same problem here. I'd love to know the reason for this.
> My idle is also rough when the motor is cold. It only lasts for about a minute but its still annoying.
> I've also put in brand new coil packs and plugs.


This is likely to be caused by carbon build up in the intake manifold. Very unlikely to be caused by an injector. Unfortunately this can only be repaired by removing the intake manifold and cleaning all of the carbon out.


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## Uber-A3 (Feb 23, 2002)

kefferpaul said:


> This is likely to be caused by carbon build up in the intake manifold. Very unlikely to be caused by an injector. Unfortunately this can only be repaired by removing the intake manifold and cleaning all of the carbon out.


Really? I know of 3 cars that had single injectors replaced and 1 that had to have them all replaced (JLT) after it happened more than once.


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## alcantara4 (Oct 31, 2009)

Carbon build up. I have a 2007 2.0t, and have had similar issues.

Mine's been in and out of the dealer for the last two weeks with the same problem. New plugs, new pcv valve, new brake sensor, and the MIL kept lighting up, for various reasons, mostly for misfires, and I had hesitation in between 3-4K rpm in 3rd gear *dsg*. Long story short I finally got it working right again, with 2K left on my warranty.

I had the coils replaced earlier this year. What finally got the misfire issue to go away was they had to completely decarb my engine. The valves looked pretty bad. They went in and cleaned and scraped it all out by hand. Heavy build up, but they got it all cleaned out and shiny again, as well as new injectors.

Now it runs like new again. I will definitely be running fuel system cleaner every 10K, and will invest in an oil catch can to prevent future problems. 

I'd recommend trying to run fuel system cleaner through it, and if it's under warranty and still causing problems, try taking it in. If you get the cleaner, I'd recommend the chevron one. If you need a full decarb, it's not gonna be cheap.


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## Uber-A3 (Feb 23, 2002)

alcantara4 said:


> Carbon build up. I have a 2007 2.0t, and have had similar issues.
> 
> Mine's been in and out of the dealer for the last two weeks with the same problem. New plugs, new pcv valve, new brake sensor, and the MIL kept lighting up, for various reasons, mostly for misfires, and I had hesitation in between 3-4K rpm in 3rd gear *dsg*. Long story short I finally got it working right again, with 2K left on my warranty.
> 
> ...


 Fuel cleaner will do nothing to help valve deposits.


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## MisterJJ (Jul 28, 2005)

Uber-A3 said:


> Fuel cleaner will do nothing to help valve deposits.


Either will a catch can. Most of it comes from oil weeping past the valve guides.

I figure you have to run a BG service about once every 20k miles to keep it from getting too bad or pull off the intake and do a real cleaning every 40k at the most.


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## Uber-A3 (Feb 23, 2002)

MisterJJ said:


> Either will a catch can. Most of it comes from oil weeping past the valve guides.
> 
> I figure you have to run a BG service about once every 20k miles to keep it from getting too bad or pull off the intake and do a real cleaning every 40k at the most.


Or water/meth injection, that's what I did.


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## alcantara4 (Oct 31, 2009)

Uber-A3 said:


> Fuel cleaner will do nothing to help valve deposits.


Not according to the shop foreman at my dealer.


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## MisterJJ (Jul 28, 2005)

alcantara4 said:


> Not according to the shop foreman at my dealer.


Than he's an idiot that doesn't know how your car works. It's a direct injection engine... direct... as in... well... direct. The fuel is injected directly into the combustion chamber. It never touches the side of the intake valves where all the buildup is. It would be like spraying window cleaner on the inside of your window and expecting it to clean the outside as well.


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## crew219 (Oct 18, 2000)

Uber-A3 said:


> Or water/meth injection, that's what I did.


Water injection does nothing to help deposits.


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## alcantara4 (Oct 31, 2009)

Interesting. Okay so then what is the general accepted way to prevent this? Someone mentioned a BG service. What is that? I don't know if I want to keep this car long term if I'm going to have to pay for a decarb every 40k.


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## Uber-A3 (Feb 23, 2002)

crew219 said:


> Water injection does nothing to help deposits.


 water/meth squirted has to have a benefit of keeping the valves clean. Especially if you start with clean valves and already have meth on the car.


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## crew219 (Oct 18, 2000)

Uber-A3 said:


> water/meth squirted has to have a benefit of keeping the valves clean. Especially if you start with clean valves and already have meth on the car.


I thought so too, but nope. 

Considering water meth is sprayed for so little duration and is actually contacting the valves very little, it's not going to do anything to prevent deposits from forming.


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## vwlippy (Jul 17, 2001)

Ok, so I swapped the coils #1 for #4 and am still getting the Cylinder 4 misfire code. The car runs fine except it is rough at idle. What to do next?


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## strangetdi (Feb 5, 2002)

Resurrecting this one. Just got this code this morning on my 2013. Time to change coil packs and see if it is the pack or spark plug.


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## strangetdi (Feb 5, 2002)

I switched the coil packs on cyl 3 and 4. Code came back as cyl 3. It looks like the coil pack is bad. I'll order a new set of upgraded ones and new plugs.

Ordered this kit:

https://www.ecstuning.com/b-assembled-by-ecs-parts/ignition-service-kit/06e905115ektn

How To: https://www.youtube.com/watch?v=rbraqrculyk


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## vwlippy (Jul 17, 2001)

Whoa! Old post 
I'm not sure, but I think it ended up being a bad spark plug.


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