Porsche Enthusiasts Club Forum

Sorry but this wont be short.

Today my car went on a rolling road. The man did his pre checks and his companion , listened to my engine through a stethoscope to rule out any pinking. As they ramped things up still listening etc ( pre power run) the car showed massive overfuelling. I was told to expect up to 3000 ( of what ever it is parts per blah blah in the exhaust) but it was rocketing to over 12 or 14,000 basically off the scale. At one point when pushed the car started to comletely cut out.

Now the reason I know this is genuine is that on the 944 run a couple of months ago , my car did this if I really flawed the accelerator , and I did mention it to Paul Mc n or Jon , I cant remember which. However the car has never done it since and I put it dw to bad fuel or something.

Now I know of course that the car was overfuelling and cutting out.

So even though I only went for a rolling road session with a view to having the car
'Pro Maxed' and then going on the same rolling road again , I now have a problem .
I now know I have a sick car. The garage tested the fuel pressure regulator and tell me that is working fine. They then tried to tweek the setting inside the top of the AFM gradually backing it oiff the spring. Now I have taken the car back but it is doing it worse than when the car went in. I am not taking it back there as clearly I only went to them for rolling road in the first place and I want a specialist to tell me whats wrong not someone else to fiddle for hours ( at my cost) and not even fix it ( or make it worse as has happened here).
The man with the rolling road has suggested it may be the wrong AFM ? , I think if anything more likely the /AFM is up the duff.

Obvious question is does anyone have any idea what would cause this overfuelling problem as I clearly need help. To be clear if you wack your foot down the car will completely shut itself off until you lift your foot especially over 70 MPH and the best way to drive the car is gently tickle the accelerator. This is now worse since he tampered with the aFM though he marked its position and put it back ( alledgedly).

Regards Mas

This is the sort of question where it would be really useful if Barry from Hartech was on the forums like he is on Pistonheads. Give Hartech a call, or e-mail them with your problem - they are very helpful and will answer.

My main problem is who to take it to. Garages are sometimes very fond of spending lots of hours on something like this and billing you even if they dont find the problem

I dont mind paying if someone knows what they are doing and finds the fault if you see what I mean. I did wonder if someone like promax would be quite likely to have the skills/knowledge. Hartech of course would be on my list but not from Hertfordshire so you have Promax , and RPM as reasonably near. I nearly sold the car a few weeks ago and im very glad I didnt , I would never consider selling a car with a problem and this must have been lurking for ages.

Regards Mas

Mas

Bit late now but I wouldnt have let them mess with my AFM.

Check for boost leaks I.e vacuum pipe leaks, j pipe, intercooler pipes split etc. An independent would pressurise the system to find the leak.

Check your throttle switch.

I had a similar thing on my turbo but not so extreme, Promax diagnosed it for me (ECU). I can reccommend them.

Rich

Since it was promax who I intended to go to ( after the power run) I suppose they may well be the best idea. I will make my decison tomorrow unless anyone else has any better ideas , and I am more tha happy to listen to any !

Regards Mas

Have the same problem with mine & it's not a turbo! Take it to Wayne. Chipwizards if you want it right. This is my main problem with performance chips. They only work if everything on your car is correct. (Even then there only right for the average car.) On 15+ year old car it never is. There are many possible reasons for this. Cheaper to check all the sensors are correct & remap than mess about. Now at least you know were you are. Most people never bother to find out! (If your AFM was the wrong one it wouldn't' run at all.) You may need a new AFM but thats a lot of money to spend if your not sure.

Frazerpart are rebuilding / Refurbing AFM's supposed to be a good job and reasonable cost.

If it is the AFM, maybe he could 'Vitesse' it .

As above I'd be inclined to check your vacuum hoses, and maybe even your filters (when was the car last serviced?).

Someone might correct me here but I think the signal from the AFM is bypassed at full throttle.

Rich

That is indeed correct AFAIK and have read.

Thanks for all the input / support people you know what its like when your car goes on the didge its a bit stressfull

The car is booked in to Promax , I will drop if off Monday, leave it with them and report back when fixed.

Ta

Mas

n update for anyone interested

There was a loose pipe on the turbo coming off under boost. It has been cleaned replaced and the car has had a test drive and is now sorted. Andrew at Promax has however informed me that the car is still running rich which I am thinking may be to do with the MAF has been tampered with ( and alledgedly put back as was !)
However They are the experts and I have left the car with them to look in to the
'rich running' and sort it out for me. I understand the pipe find fix and test drive took just over an hour so , i hope they can sort the 'tuning' as quickly


Regards Mas

I can almost feel your relief. Glad it is nothing major and you'll be back on the road soon, faster than ever.

You could of just went for a re-spray, in RED. That would make it faster.

Lee.

Thats great news! Mine too runs very rich at the top end. Remap required to put it right. But had you not put it on the dyno the over fueling could have wrecked your engine. Washing the oil off the bores.

Cheers both

" Glad it is nothing major "

They havnt cured the running rich yet m8ee, lets not count my chickens

Regards

Mas