# '06 A3 Misfire issue nobody can seem to fix....



## cartelkilla13 (Oct 18, 2009)

i have a 2006 Audi A3 with 68k miles. about 5 months ago it started misfiring when accelerating from a traveling pace. the coils were under warranty and i had them replaced. next, i found the cams were from the batch of bad cams produced by Audi, so I had those replaced, and the cam follower. no damage was done to the fuel pump....still misfires. the car has GIAC installed so next we flashed the programming back to stock settings







the car is slower and the misfire has gotten better, but it still misfires.. the shop foreman hooked it up to a computer and we went for a spin. he was telling me the car has a 25% lean misfire. what should i do? should i have the coils checked again? all 4 plugs are brand new.. could it be the GIAC? also i have a P0420 code for a Ctalytic Efficiency Below Threshold but my O2 sensors were checked and are good, and my APR turbo back exhaust supposedly has a high peformance CAT(what the previous owner told me) HELP!


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## CoNGLoMeRaTeGTi (Apr 4, 2007)

*Re: '06 A3 Misfire issue nobody can seem to fix.... (cartelkilla13)*

Any cold start issues? Try aligning the TB with basic settings. I think it's 060


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## marine78 (Feb 12, 2009)

I know how you feel, I've been there. Try the TB alignment, then try replacing the cheapest things, like spark plugs, air filter, and fuel filter. Next, you'll probably need to pull the intake manifold and check the conditions of your intake valves. If there in bad shape, then you'll need to consider that your fuel injectors may also be in bad shape. Maybe a fuel system cleaner can help. The cat is reading a code that can be looked up for futher diagonics. Someone here will get you threw this.


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## djbrkb (Jun 29, 2008)

*Re: '06 A3 Misfire issue nobody can seem to fix.... (cartelkilla13)*

hi, having the same prob with my 06 2.0.. my car has 100k miles and has had the apr stage 1 in it since 20k miles.. find it hard to believe your chip upgrade is causing your prob - since i also have prob and have had no issue for 80k since the upgrade. my issuue showed up last month right after they replaced my coils and plugs under warranty.. car shudders when cruising and idling but is still very responsive when i get on it with no power loss. car also does not start very cleanly when cold. the check engine light came on and was an engine misfire code. it went away on its own and has not come back even with the misfiring continuing. when i went back i was told that carbon buildup on intake valves is my issue - they want $1000 to clean this out.... doing research before i go that route. just thought i would inform you - maybe we can figure this out with shared info.. david


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## djbrkb (Jun 29, 2008)

*Re: (marine78)*

whats a tb alignment?


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## iGen3 (Mar 21, 2002)

*Re: (djbrkb)*

clean your intake valves manually and replace your injectors while you are in there. worked for me YMMV.


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## RABIDRABBIT1983 (May 13, 2003)

*Re: (iGen3)*

what plugs are you running?
If the plugs are correct I would start with a fuel filter, they are known to cause similar issues. 
If not the fuel filter..........I would speculate horrendous carbon buildup on the intake valve issues the FSI & direct injection platform is plagued with. 
If the fuel injectors where faulty you would think you would have a lot more driveability issues or CEL. On the other hand if I was pulling the intake and injectors are not to bad $$ wise I would replace them given the PIA they are to replace, but thats me








Most High flow aftermarket cats will throw a cat below effeciency threshold p0240 code. They simply dont clean things up enough to pass the acceptable limit in the ECU. Here is a simple fix http://store.42draftdesigns.co....html I have used one on a catless race VW and it worked great!


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## amckernon1028 (Apr 14, 2009)

*Re: (RABIDRABBIT1983)*

I had a problem like this but only up top of the rpm band. I changed coils, plugs and this still didn't totally fix my problem. I know only have the issue in 6th gear after 125mph? It is better with new coils, plugs but what now? I feel your pain or irritation. 
I have also been told it could be an injector issue, I will see when the S3 injectors are installed in a few weeks.


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## rkmoore (Dec 14, 2009)

*Re: (amckernon1028)*

had a similar problem with my 08 gti. replaced plugs, coils, hpfp, cam follower etc and in the end it was the fuel filter, intank pump and sensor. problem solved. good luck though I hope it's not that cuz that ish is expensive.


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## AliciaVR6 (May 6, 2003)

Ugh, same problem here, 06 a3 2.0 with 67k. Replaced plugs, next is fuel filter... but my problem is only after cold start, idles rough, then drives rough for about 30 seconds. Its getting worse with time, had car into dealer few mos ago, they said they could find no problem, replaced coils under recall, cleared misfire code, problem came back in a week. Now its every morning. Not really sure what to do, inspection expired. Cant get inspected with CEL on.


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## dubbin415 (Nov 1, 2007)

i had this problem, cel and misfire cylinder 1 right after cold start up. Funny thing is, I used 2 bottles of Chevron's injector cleaner, and now everything is fine? No cels, no misfires, no engine stumbling after cold start ups. Running like a champ!


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## [email protected] (Jan 6, 2006)

iGen3 said:


> clean your intake valves manually and replace your injectors while you are in there. worked for me YMMV.


I'm thinking that this is going to be the solution to a lot of these "mystery misfires" around 60k.


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