Audi S3 Miss Fire

[Charlie23]

Hi Guys & Gals,

I just purchased a 2007 S3 that has a very bad miss fire. Was hopping it was something easy but doesn’t look that way at the moment.
It has a very bad miss fire and won’t idle or anything, constantly hunting and missing. I have replaced the Coils, plugs, pcv & MAF sensor But still the same.
The car has a brand new HP fuel pump on it which was my next check But does anyone else know anything else to Check? There is no EML on so indicates that it’s mechanical fault really but you still Never know. Other causes i have been thinking could be Injectors, Bent valve or maybe head gasket but it starts first time every time just misses and hunts like no tomorrow.

Any thoughts or advise much appreciated.

 

[NHN]

What was the state of the cam follower & did you check the inlet cam for any damage like rounded off edges?

 

[Charlie23]

Thank for the Reply.
Had it compression tested 140 on all cylinders and then a smoke test, smoke coming from oil filler cap and also inlet manifold area. On inspection small pipe that comes off the head down to the inlet manifold had broken off. Repaired and put back on and now car is perfect well running ok for now that is.

 

[Charlie23]

Another bit of hesitation has started with the car Grrr

when the car is cold drives all fine and boosts well, once it gets hot temp gauge goes past 1/4 the car starts to hesitate/hold back when giving it the beans?? I have replaced the Fuel pump with a loba as though it might be that, still the same, replaced fuel filter as it’s like it’s not geting enough fuel and and still the same. But like mentioned when it’s cold from first start up it’s a beast and boosts like it should? Could the temp sensor or thermostat cause anything like this??

 

[ch1z64]

First port off call with any misfire in my opinionis have it scanned with genuine Vcds ( check site map for peeps) then u will find out if what 1 , i had simillar prbs with my 2007 S3 done all testing compression , rail test and mechanic done something (oldskool Mechanic)and yip was my injector 2 waa goosed

Sent from my SM-G970F using Tapatalk

 

[Charlie23]

First port off call with any misfire in my opinionis have it scanned with genuine Vcds ( check site map for peeps) then u will find out if what 1 , i had simillar prbs with my 2007 S3 done all testing compression , rail test and mechanic done something (oldskool Mechanic)and yip was my injector 2 waa goosed

Sent from my SM-G970F using Tapatalk

Hi mate,

haven’t had it scanned with VCDS yet but on Carista etc there are no fault codes? Get the odd Bank 1 to lean but that’s only now and then. If I take the car out now while it’s cold will be mint when it warms up it starts to hesitate no EMl or fault codes?

 

[prt57]

Whilst your problem was there before you added the Loba pump, you need to be careful as it could add too much fuel. This would need mapping in really.
Have you checked the plugs. Most recomnend NGK BKR7EIX. Do you have a mate that could let you try their coil packs

 

[Charlie23]

Hi mate, all brand new plugs and Coil packs. As for pump everyone goes on about don’t fit unless your getting the car mapped etc can’t say its ******** but I’m on my 8th S3 and never had a problem. Even ran my last S3 Stage 1 R-Tech map with Uprated fuel pump for 6 months like it, made 350bhp before the map and 355 afterwards

 

[prt57]

The Loba increases the midrange torque figures and not so much the BHP.

 

[Charlie23]

Does anyone think it could be an injector? Just strange how it’s fine when car is Cold and gets worse as the engine temp rises??

 

[prt57]

If you have been to RTech before they are wizards at diagnosing and sorting out issues like this.

 

[dave_beastttt]

@Charlie23 how's your dual mass flywheel? Any noises/chattering?

 

[Charlie23]

@Charlie23 how's your dual mass flywheel? Any noises/chattering?

No mate all good on that. Now it’s abit colder the car is running mint? But leave it idle for 15 mins temp goes half way and the problems start again??