964 Running rough Help

[daleint]

After selling an old Targa (74) last year I thought it was time for a newer Porsche and purchased a 92 (964) last weekend and after driving it for about 200km it developed a few problems like when cruising at about 100kph the car would just jump like trying to drop down a gear and continue. this would happen in D or in the semi manual mode and even when going slower. I tried accelerating reasomably fast in D mode the car did not want to change up and the car just cut out and cruised to a halt. The CAT light was on for about 15 seconds whilst trying to start the car and throttle responce was poor and pumping the throttle did not increase any engine revs untill the car eventually ran. Ten mins down the road and several jerks like the car wanted to drop down a gear and the car stopped again.
I have taken the car to a reputable Porsche dealer in Christchurch NZ and was interested to know if anyone else had had this problem? could it be the compure? I was told the car had just had a new one.
Re the CAT light coule the converter be stuffed.
any info would be appreciated.
Cheers
David Dale

Check the secondary drive belt on your distributor. they are known to break and it it hasn't been changed by now, it's due.

Go to http://www.porsche964.co.uk/ Look under technical, there is a good article on the distributor belt.

What ever you do don't drive it with a broken belt. A friend did, burned a hole in one of his piston, not good.

Good Luck, Don 93 RSA

[daleint]

Thanks Don. I will check to see if this has been replaced.
DD

[dick911]

Hi there Kiwi,

Beside the ignition distributor belt also replace the DME relais.
This relais somehow has his influence on how your engine is running...
DME relais is fairly cheap.

But surely check the belt!

Good luck,

dick911

[daleint]

Thanks for the info. I just had a reply back from the mechanics and they said no faults with computer according to their KTS550 tester. I will pass on the DME information. Thanks again and I hope it will be sorted by the weekend. cheers
DD

[daleint]

Car is still not running correctly, mechanics said they have checked the secondary drive belt and thats OK. Cat converter is OK. not DME so they say has anyone got any other ideas what the problem may be.
cheers.DD

[colo964]

The DME tester won't tell you if you have: bad coils, wires, dist/belt/caps, plugs or an air leak, clogged intake or exhaust pipes, fuel filter/pressure. Check those things.

BTW My car did something similar a few weeks before my fuel pump died.

[daleint]

Thanks for the reply. I am looking forward to these guys at Autothority to fix the problem so I can have a decent drive in the car. I have passed your info onto them and thanks for replying. any help at this stage would be good and I hope I have not purchased a lemon. Regards
DD

[daleint]

Well problem is still there and new fuel pump fitted DME relay was by passed and still the car cuts out. new filters fitted and new battery. earth checked. the car runs ok then looses power and just splutters and cuts out. The guys at the workshop had to have the car towed in, they ran the car next morning for two hours and it ran fine. any more ideas please. DD New Zealand.

[herman maire]

I would give your flywheel sensors a check .... They are magnetic sensors that give your motor its timing and they can be checked , you need a basic ohm reader and a shop manual for the spec ohm readings.

I would even check the teeth that the sensor gets its readings from just to be sure they are not damaged.

[MBEngineering]

HI from the drive 'D' it is a tiptronic, then has the engine been set up and adaption been set when hot at idle, also the gear box will require adapting, if the battery/control units have been disconnected or the battery has been flat, otherwise it will run/try to run like a bag of *****.

regards mike

[daleint]

Hi Guys
the bloody car is still not running. sensor voltage on flywheel was 75volts at peak. the People at Autothority in Christchurch NZ wondered if this was correct and they have had a dead battery and fitted a new one also a second hand computer and still the car cuts outand even power to the computer is out. 3 times in one week the car has been towed back to the Porsche place. embarrasing to say the least. I will tell them about the set up re gearbox and at present its at an auto electricians having a going over re the electrics.
Anymore Ideas you can think why the engine cuts out.
Thanks
DD New Zealand.

[FRED/LI]

It may sound severe, but the DME could very well be fried.
Had it happen on my 964 a few years ago. Impossible to diagnose with standard methods and tools. Swap it with a friend if possible. At any rate, rule out this possibility.
It can be rebuilt......don't go for new.
Hope you find the ghost. Good luck.