944 - throttle/ fuelling problem. Help!

[northo]

I'm having some problems with my S2, and was hoping that someone might have ani idea of what it might be.

Went out for a run a few weeks ago - the car was running great. On the way back had to drive through a lot of standing water, but no problems encountered. A few days later, started her up and lots of black smoke, engine not happy and then it just died.

Sent her down to a local specialist, who diagnosed a knackered Mass Air Flow Meter (whatever that is!), and replaced it. Car appears to run and idle OK. Took the car out for an 800 mile run, and the car is spluttering at around 3000 rpm. With the throttle fully open it accelerates fine, but there is a stutter as you open it, and it is not happy unless at full throttle.

Sent the car back, and two weeks later have not managed to fix the problem. ECU and DME have been checked, it has a Blitz chip which has been checked and replaced with the original, but this has not made any difference. The car is guzzling fuel like never before.

One theory is that the previous owner had fiddled with the MAFF to compliment the Blitz chip - it appears to have had a whole deliberately put in it.

Any ideas?

 

[edh]

Just checking - is it an AFM (the standard air flow meter) or a MAF (mass air flow sensor) ?
- I'm guessing it's likely to be the standard AFM

Was the replacement a new part? - if it was second hand it could be worn & be causing your problems. That's my suggestion for the first place to look. (My faith in Porsche "specialists" has taken a bit of a knock in the past 2 -3 months [8|] )

Whatever it is, you are overfuelling & don't want to be running like that for very long. Check your plugs - are they all the same colour or is one blacker than the rest?

Pics of the hole in the AFM would be interesting (sounds very strange to do something like that)

 

[Black_JPN]

Was the DME replaced with a new one?
New plugs, dist cap etc?
Dirty fuel?

 

[northo]

DME checked and replaced with a new one - no change. The MAFF was a recon unit. I have run 3 tanks of fuel thgroughy it, so should be fine, and used a bottle of Forte injection fuel system flush, which got rid of a hell of a lot of crap. Dist cap , haven't checked. Plugs have been checked and cleaned.

 

[SimonP]

Has the fuel pressure been checked...?

 

[Diver944]

Similar to a problem I had with my engine temperature sensor a few years ago. When it fails the ECU thinks the car is stone cold all the time so it's like running with an old fashioned choke wide open - very rich, sputtery on acceleration and black smoke.

It's the blue sensor at the front of the engine block below cyl #1 in a direct line back from the bonnet catch

 

[Alpine]

Ed

Not sure I can help, but is that your car on your profile with the blue wheels? - looks well cool.

Didn't you used to have a red S2, or am I confusing you with someone else?