Porsche Enthusiasts Club Forum

Hi all 944 s2 owners, This is my first post on the forum and hoping you can help with a problem I have not encountered before. I have a 1990 S2 which has had a hard life and is being given loads of ££££TLC !!!, Nearing the end of extensive restoration including a full respray I now have run into a odd engine problem. After running at idle for two or three minutes and reaching working temperature the revs started to fluctuate up and down very erratically and then it died. I managed to restart the engine for a short time and only able to keep it going by pumping the throttle. It will not restart today, so have left it to see how it goes when its cooled down tomorrow. The engine has had the following work done: Head Gasket including a full head rebuild, Belts, Water Pump, Refurbished Air Flow Sensor, Engine Temp Sensor, DME relay, Starter Motor, O2 Sensor. My thoughts are either a bad electrical connection to a sensor or Cam Hal sensor, Throttle Position switch or ECU?
Any help would be appreciated, Many thanks, Martyn

Similar 'pulsing' on my 924S - starting on choke OK, but then as soon as it had warmed up and tried to go off the cold start, then revs would momentarily drop then immediately go back up - this happened in a repeat cycle every three of four seconds. No eventual stall tho. Fault traced to a knackered Idle Control valve, replaced with a good one and fault immediately cured

Hope its the same problem, it does sound like it

All the best for the New Year

Hi Rob, thanks for the reply, really nice to get some feedback, much appreciated! I will look into this as a possible cause. The engine has been running fine, but looking back over the last few months the engine has been run for short periods of time whilst off the road just to check all was ok. On occasions i did notice it was running a little uneven at idle and sounding a bit unwell! after giving a good reving the problem cleared, so put it down to the time it was just stood not being run. I had a similar problem on my 944 2.7 which turned out to be a aftermarket alarm affecting the fuel pump. I will keep you posted when I get a chance to get back to it. Many Thanks again Rob for you input. Fingers Crossed I can get it started or its back on a trailer to the mechanic and more ££££s

leaking inlet manifold gasket caused erratic idle on mine.

...and if its not the ICV then maybe just a loose vacuum line, that has made my 944s2 cut out, misfire and hiccup when running and difficult to restart on more than one occasion.

This would be the cheaper thing to look at first!

The cold start valve has a rubber pipe that the previous owner of my car had extended and this was folded over causing starting and running probs.

Hi Everyone, Thanks for the new ideas, I will give the hoses a good check over. The inlet manifold was a suspect when It failed an emission test. After the head gasket was replaced a inlet bolt was not fitted properly. My current mechanic could not believe that the Porsche Specialist who did the work had tried to use a bent bolt! This was rectified and passed emissions, so I can only assume all is well as far as that is concerned. It was really odd that the engine after idling for a few minutes just became really erratic and then died. Very worrying not being able to re start it! Since then I have restarted with no problem, but cautious about running it for to long until I can check things over and look at all the items you have all mentioned. Again thanks for all your help so far.

Hi everyone, update to erratic idle and start problem. After checking for air leaks and hoses the problem continued with a really erratic Idle which showed only occasionally when started. Some times all seemed fine and then without warning I would start and it was running poorly like it was running on three cylinders. I checked for poor plug leads by running in the dark and looking for tracking to earth but nothing. I considered that this could be a problem with fuel delivery and after reading on line about similar problem, the only component that I had not been changed was the ecu. I purchased one on ebay for £125 and have just installed it. So far so good. The car has been started a number of times, first turn of the key and run up to temperature with no problems so far! A 20 minute road test was also good. Could this be the infamous dry solder joint problem in the ecu causing the injectors to miss fire? Fingers crossed that this £125 was money very well spent...... Not sure about a long journey yet..confidence has taken a bit of a hit. Next problem to solve, water leaking into the boot and battery compartment! Living with a 944 is hard, but worth it!

Fingers crossed that that sorts the problem out for good ..

Water in the boot?? Yup, me too, and I can't see how it gets there either! I eventually resorted to drilling a drain hole and, once everything was dried out, caking everywhere with cavity sealant spray..

HTH

Greg

Fingers crossed that that sorts the problem out for good ..

Water in the boot?? Yup, me too, and I can't see how it gets there either! I eventually resorted to drilling a drain hole and, once everything was dried out, caking everywhere with cavity sealant spray..

HTH

Greg

Water in the boot is normally caused by the drain tubes on the hatch pins not connected/blocked or missing?

Dave
CT

It's a cab Dave, but I'll check to see if there are any drainage pints I've missed in the channel around the boot lip ..

Worth checking the rear light clusters they have been known to leak.

Cheers every one for your ideas regarding the water leaks. The problem with all of this is the rear of the car has had some serious body work done including a new rear offside wing due to heavy corrosion caused by a botched repair by a previous owner. The tail gate, lights, hatch seal, catch and lock have all been removed and then replaced. I have already taken out the light clusters and resealed them into place and replace the lock seal with a new one. The drains from the catches seem good. Ill be checking the sunroof drains next. I read online of a great tip to trace water leaks…Dust the area with talcum power and then close the tailgate and spray water onto the car then check to see the water tracks if any. Ill let you know if this works!