dfinnegan

I was thinking of you with regard to this issue . . . glad you've checked it. I have intermittent hesitation when cold. Seems I should put "check the screen" on my list. The list is getting long!

MMartini

Hi, I removed the airfilter cover and filter but no sign of the air flow meter plug... I was hopen for an easy solution to the problem but bad luck must be that on the 1991 model this problem was already solved. All the electrical has been checked by the Porsche dealer so I guess I should check the filter screen now.... anyone who can explain how to proceed?

Thanks, Marco.

dfinnegan

See post #9 of this thread for a picture showing the electrical connection on the back of the AFM.

dfinnegan

There is a wire bail that gets depressed to remove the connector. Look at any of the connections that are visible on the intake. They all of the same wire bail to hold the connector in place.

Indycam

A fuel filter problem causes a loss of power at high speed / high power , as the flow of gas is not sufficient for the needs of the engine . I have never seen a fuel filter that flows ok at high rpm and then chocks the motor at low rpm and or idle . I have read about the theory that the clog comes and goes but I don't ever see how that could really be .

"All the electrical has been checked by the Porsche dealer "
Is this the same dealer who put on a set of wires to fix the problem , if it is , they already lost my trust by not finding and fixing the real problem / charging you for parts and labor that did not work . If you want to trust that they knew what they were doing while they got it wrong ?
I would go back to basics , lots of running problems that are written about on this forum are caused by bad old ignition parts . The ignition parts go bad . Caps , coils , rotors ,wires etc , go bad . They are easy parts to look at and test . If you think its a fuel pressure or flow problem , test the fuel pressure while its running before you pull anything apart .

911addict

Get them to check the wiring in the loom, that was where my circuit was shorting.

MMartini

Wiring in the loom? where should I check that?

911addict

Sorry, not a techie myself. I was told in the "engine wiring loom". Your garage should know. Worth a try before spending money on expensive components.

MMartini

Seems things got worse.... got all the wiring checked (and replaced) but no problem was found. The car was not used for a week and today I went for a ride but the engine runs with "hick-up" all the time and also accelerating doesn't go smooth. The Porsche dealer thinks about replacing a part of the injection system but this would be expensive! any othe suggestions?
Thanks, Marco.

dfinnegan

Have you checked the alternator? It seems there have been a few cars lately that needed a replacement and I think I've read that if bad it can contribute to this type of poor running.

colo964

Could be a bad contact inside the AFM. There is a brass or copper arm that tends to break off. I had to solder some stuff in mine a few years ago, but don't remember all the symptoms. If you are desparate, pry off the black plastic cover on the AFM and look around or at least shake it to hear for rattling.

dcbailey

I just had this problem. Low speed surging, power drop off, but only intermittently. Some times it worked fine. Drove me nuts. After a lot of work by Zim's in Bedford, they isolated it to the #2 cylinder, and the spark plug wire not being fully snapped onto the plug. Unfortunately, you have to take off a lot of things to get to it, though. I would make sure your spark plug wires are firmly attached, and if it still occurs, check the ohms through them. Hope that helps. Hats off to Wayne and the guys at Zim's. Real experts.

Indycam

My guess is the hick up is a misfire .
My guess is somethings not right with the spark .