dont know if this is the right forum.

a mate of mine has a 1.8 20v turbo audi tt on a 2001 plate.

has bad miss fire under load, stinks of fuel and pours out black smoke. it has had a new MAF sensor, could only get 1 new coil pack so changed them one at a time using the new one, wound the actuator back down on the turbo and put the standard ecu back on.

still got this misfire problem any suggestions would be help (we do not have access to VAG-COM)

Why would the actuator have been moved in the first place?

he did it to increase the boost even though he blew his turbo a couple of months ago prob by doing it

Trouble is it doesnt increase the boost as the boost is controlled electronically by the ECU.

I'd be doing a compression check first of all.

head gasket appers to be ok, already suggested a compression test as this would show a broken piston ring or a stuck valve but has been told by several garages it wont be of use as they say its a fuel or ignition problem.

have found someone with access to vag-com but got to wait till tues or weds when they get their new lead

Basics first, if you know the compression is ok then you can move on. Burnt out valves aren't uncommon especially if its been played about with in a somewhat 'dodgy' manner, but you need it on a diagnostic machine.

I saw a Lancer Evo with similar symptoms recently. Nothing wrong with its "go"; just smokey and smelling of fuel. Which makes me think of the MAF or Lambda sensor.

If its missfiring then its something more than a MAF or Lambda probe.

Doesnt sound good either way, can you tie the missfire down to a cylinder? Does it missfire at all on idle?

I promised myself I wasn't going to do this!!

The last time I heard a car with EMS and what the owner described as a "misfire", it was hunting on idle, and he'd thought that was a misfire. Cutting a long story short, the problem turned out to be a dodgy remap that had just added fuel on every site!

So basically I'm not arguing with you Ross; just suggesting a possible alternative.

Yep i'd agree with that and your right.

The fact the car has had a new turbo and has been tinkered with very crudely by someone who obviously doesnt know what they are doing leads me to think something is broken now.

just a quick update

the tt went to audi at derby yesterday to be put on diagnosis, they had a few problems pop up all relating to boost pressure but they said that the sensors were fine and could find any problems, not saying they no nothing about the car but the said the standard recurc valve was not supposed to be there as they dont come with them when new? so wouldnt go any further with their investigations.

the car has now made it as far milton keynes (used a full tank of fuel and couldnt keep up with my octy deseil) to a company called backdraft who are testing each individual sensor, compression testing it etc as everyone round her said they were unable to do for a week at least.

will let you all now the outcome when it gets back to derby

cant tie the miss fire down to any perticular cylinder the coil packs have been uplugged one at a time while the engine was running and made no difference. the car was running fine with re-map and 2 month old turbo untill friday (the new turbo fitted was a hybrid with what i dont know)

Now completely flummoxed, unless the hybrid turbo is overboosting it, the fuelling is being delivered for the new boost, and the pop-off or bypass is activating to reduce the manifold pressure, but the fuelling is arriving for the actual boost, which would give you a very rich running engine!

had a call from the guys at backdraft in MK and found the maf sensor, boost pressure sensor, coolent temp senor, recurc valve, one of the coil packs were failing and a slight split in a turbo hose, the ecu however is fine, just that no ecus seems to be picking up the faulty sensors cus the voltage across them has not yet dropped enough they reckon. so far a cost of around

ouch! so what seemed like a cheap path to power has turned into a bit of an expensive nightmare? why does this feel so familiar :rubchin:

So everybody was partly right! Ouch!

plus side is though its running just under 400bhp, the guys who are doing the repairs also race tts and they say its almost as quick as their race car but handles alot better when he told my mate that he had had nearly ?50 out of it with a split turbo pipe

ok got the car back yesterday morning at a final cost of just under