Testing for a bad/clogged injector

[urban96]

I keep getting P0302 - misfire cyl2.

Replaced all spark plugs (NGK gaped at .032) and new coil on cyl2.


Same code came back.

Going to try gaping down to .028 next.

If it comes back again is could I use this scan tool to tell if the injector is clogged or stuck open? Or would I need a VCDS to log it. What sensors/data would I have to monitor?



If I do have to replace an injector I plan on cleaning carbon while the intake is off.

[atomic13mjb]

Move the injector to a different cylinder, it's easy to do. If you end up with the same problem then it's likely your cat is starting to plug. It's a common issue. I just went through this on my S4.

[907DAVE]

Huh? The Injectors are not easy to swap, nor does that point to a plugged cat.

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[Okedokey]

I think he means coils.

[Charles.waite]

I think he doesn't realize that FSI injectors aren't port injectors.

[907DAVE]

OP, without some specialty diagnostic equipment and proper training it will be hard to prove your problem is the injector. Keep it simple and rule everything else out, then, chances are it is the injector. Start with a compression test and see what you're working with before you invest any more time or money into solving this issue.

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[Charles.waite]

OP, without some specialty diagnostic equipment and proper training it will be hard to prove your problem is the injector. Keep it simple and rule everything else out, then, chances are it is the injector. Start with a compression test and see what you're working with before you invest any more time or money into solving this issue.

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This. DI injectors are a very different animal than port injectors.

[urban96]

OP, without some specialty diagnostic equipment and proper training it will be hard to prove your problem is the injector. Keep it simple and rule everything else out, then, chances are it is the injector. Start with a compression test and see what you're working with before you invest any more time or money into solving this issue.

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Im hoping its not the injector, dont really want to pull the manifold. Im just thinking ahead a little if the small things dont fix the problem.

Today I gaped the plug down to .028 and swapped the 1-2coils (even though coil 2 was just replaced)

Checked all the coil wiring and didnt see any cuts/shorts

[Sanjman]

You can try fuel injection cleaners as a start. They usually are for preventive measures but hoping it might penetrate enough.... (haha penetrate) to dissolve some of the gunk. Throw some seafoam into the tank


Your best bet will be pulling the manifold and injectors though. It will be a good learning experience and it will be easier the second time around

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[Charles.waite]

Audi makes a special additive actually for the direct injectors. 034 Motorsport sells it. It's called G17 I think.

[urban96]

Before I refill next time ill dump in some seafoam.

Drove it a few days now and the CEL hasnt returned, I think re-gaping the plugs did the trick.

[BenMTL]

Which reminds me, is there any way to check the performance/condition of our injectors via VCDS?

I'll be removing and cleaning my stock ones soon, but if 1 or more are performing well, I'd replace them while I'm in there.

[Sanjman]

Unfortunately, there aren't individual pressure sensors for each injector, just the rail pressure which is all four. If one is clogged rail pressure should theoretically increase momentarily before it gets regulated back down to the specified rail pressure. Not sure if VCDS is fast enough to see that initial spike in actual rail pressure.

[atomic13mjb]

No, I meant injector, not coil. If after swapping the injector to another port the condition is exactly the same then I would be looking at the cat still. If you are unable to release the exhaust gasses the way it's designed to flow then you end up with higher cylinder pressures. That can cause a cylinder or two to act as he's describing. Believe me, I chased this for 2 months on my car and refused to believe a plugged cat was my issue. The moment I made piggies the problem was solved. Also, for the record, I do know the difference between port and FSI. I realize my car is the V8 and this post is a 4. I was just referencing against my experience with this issue. Didn't mean come in guns blazing so please excuse if I'm out of my league here.

Does anyone know if the OP fixed the problem permanently? Having to close up the spark gap from factory settings would tell me there's more cylinder pressure building and blowing the flame kernel out. Wondering if the car has been modded with more boost?

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[gavin_j]

I had a misfire a while back. Did plugs then coils. Misfire stuck with cylinder 3 even after moving them around. Compression was great.
Suspected injector. Ran it on a MotoVac machine that hooks to your fuel lines essentially bypassing the low pressure system and pushes through a very concentrated fuel system cleaner. Ran way better for a while. Misfire came back after a few months. Did an injector and a carbon cleaning while it was open. Runs better than when i got it now.

[StatusQuo]

+1 on the seafoam in the gas tank.

Put a whole can in half a tank of gas. See if the misfire goes away by the second fill up.