Porsche Enthusiasts Club Forum

There are other similar threads but they appear to be for the 944.

Sometimes when I have to drive in low revs (like waiting for slowcoaches at roundabouts) the car stutters and conks out. It always starts again needing revving to keep it going, which is a bit inconvenient keeping it in neutral with queues around. Problem has only occurred when engine hot.

The car has no ugly electronics which is one reason I like it, and I can't see a fuel pump suddenly only deciding to work temporarily when hot for high revs.

One suggestion I had was to use a fuel system cleaner (by a guy selling fuel system cleaners).

Any suggestions would be great, and avoidance of just using initials when referring to parts would be great too as I've only had these things for about 25 years and still don't fully understand what the bits are that my earlier cars never had...

It helps if you state the year of your 924, there are a number of variations in Spec over the years, later ones do have electronic ignition. Depending whether your car is in continual use, or whether it has been laid up will affect issues also. Initially, I would change the fuel filter and use an injector cleaner to see what effect that has.

Thanks, it's a standard 924 model, 1983 registered - with distributor and rotor arm. It's been used occasionally over the past year, not laid up for too long.

Hi

My initial thoughts are either an electrical component breaking down when it gets hot or an air leak appearing with heat although I'd say this is unlikely.

Does it start fine from cold and idle happily? Does the problem arise if stationary but fine if sitting at speed??

Thanks

Your car has electronic ignition. The biggest failure of most 924 owners when getting a problem is to start ripping things apart without being logical. If the car has been running reasonably well up to now, and hasn't been interfered with, the most likely cause is lack of use! Start with simple things, has it been serviced?, replace air and especially fuel filters, run it on a decent concentrate of injector cleaner for a while. Unleaded fuel is horrible stuff when left for any length of time, it gets gummy and attracts moisture, and the one thing the mechanical K jet system hates is sticky components.

From cold it's very happy!! Also when it occurs, it's only when I have to stop or drive really slowly. Fine at speed.

I'm pleased you mentioned the ripping apart syndrome - the whole point of having a 924 is having a relatively simple sports car, although alas, that doesn't equate with inexpensive maintenance over time...

Filters have been changed. Will try K-Seals injector cleaner as the stuff in Halfords doesn't inspire me . That will also give an excuse to take it for a holiday!

The 924 is a simple and inexpensive car to maintain if you DIY, if you have to resort to a Garage, then it does become expensive. First you have to find one that understands Kjetronic, and then someone who can diagnose rather than plug in a diagnostic tool to sort things, rare today!

Unfortunately diagnosing problems in old cars does sometimes become a case of swapping parts over for known good ones to eliminate problems, not cost effective in a modern world.

Can you replicate the problem on your driveway? If so maybe start with a fuel prssure test to make sure the warm up regulator is working as it should. This would also tell you if the fuel pump or related components are working as they should.

No it only happens intermittently after driving for a while, sometimes, and then only temporarily so can't see it being an issue for those components

The most likely components to fail when hot are the coil and fuel pump relay, as a rule, these won't enable you to start straight away, but only when they cool down. My best guess at the moment would be a sticky lift pin in the fuel distributor, which may be helped by use of an injector cleaner.

Will try the cataclean system cleaner first when it pops thru the letter box!