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Rough running & loss of power

BillMain

BillMain

New member
I thought I would post this to see if there are any quick checks I could do whilst waiting until next week when the independent specialist garage opens.

On the way to a PCGB run today when my 964 lost power on the motorway at circa 85mph ,or maybe 70mph:), I pulled in and switched off the engine, restarted and the engine is running on less than 6 cylinders, spluttering and obviously down on power. I headed off hopingh it would clear however, this was not to be and I also worried about the distributer drive belt failure as mentioned here before so, I pulled over and arranged recovery.

The car has been running well over the winter with no issues and there was no indication of an impending failure leading up to the incident. I had already completed about 40 miles across country and dual carrageway before going on the motorway for about 5 miles.

Anyway, rather than sit here and wonder I thought I'd post this and see what you guys think, what should I check etc, hopefully not just my bank balance!!

Thanks

Bill
 
If you want to check just remove the distributor caps and see if either of the rotors spin. Spinning = broken belt, resistance = OK.

ETA it's the bottom (secondary) distributor that you need to check for a spinning rotor. Unfortunately this is the most awkward to remove as you really need to remove the blower pipe to get access to the screw holding on the cap on that side.
 
Bill,
I had a similar problem once, I was advised to check the Elec plug connections close to the AFM at the top of the engine. The theory was they can get damp and the signal from the airflow meter can become inaccurate.
I did that and lightly oiled the terminals (rightly or wrongly) and no issue since.
I was thinking Dist Drive Belt just like you.
Good luck
George
944T
964
 
Steve, George,

The dist drive belt is Ok, thankfully and, all the plugs and sockets appear to be as they should however, she is now trussed up in the covered trailer for a trip to the independant for checking out this week.

I'll let you know the outcome..[&:]

Thanks

Bill
 
Looks like the ECU, still waiting on the full diagnosis from the garage as it's been away for evaluation. A spare from another 964 was put in a nd the result was a "night and day" difference.

Thanks

Bill
 
ORIGINAL: BillMain

Looks like the ECU...
Click to expand...

Ouch! The ECU on the 944S2 went and a new one was around £1K. Buy 2nd hand, you'll save a packet, I would be surprised if it is a particularly common fault so you should be alright. Also, you can buy 6 or 7 2nd hand ECUs for the price of a new one.
 
The specialist I use has someone who repairs ECU's and can get various repair items so this should be a cheaper option, unfortunately, he has never had to order the part which has gone on mine!! The replacment ECU is £1,400.00 from Porsche so hopefully the repair item is available.

to be continued.....
 
I was offered the option of a repair but it would have cost about the same as a 2nd hand unit and there was no guarantee that they would actually be able to fix it.

That one on e-bay looks a bit steep, try the specialist breakers advertised in PP.
 
Bill,
Here's my (call it cynical) suggestion.

Ask to see your ECU, mark it physically, Ask for it to be fitted.

- my expectation is it will run fine.

If your ECU has failed, the replacement will most likely fail for the same reason. Perhaps a Sensor or wire has shorted, but if so it will take out the next ECU in the same way. Alternatively - if a small amount of invisable corrosion has caused high resistance on a connection and confused the ECU - causing the engine management to mis-manage the engine due to incorrect inputs, then removal / replacement will fix the issue. I'm not saying the ECU cannot fail, but its pretty rare....

Believe none of what you hear and half of what you see...........
Goodluck
George

944t
964
 
A quick update on the repair.

The ECU was removed and sent for repair as a first option as the replacement Porsche item is £1400. It could not be repaired so an exchange unit was used, all wiring has been checked from the ECU through to the engine wiring harness.

DME relay changed as a matter of course and the old one in the glove box as a spare.

The car is running noticeably better and following the discussion I had with the garage it was showing some symptoms, albeit intermittently before the failure.

Happy the car is back and off to a club meeting tonight with the prospect of a good run home on appropriate roads, with a lighter wallet!![:(]
 

Bill,

Who was the specialist you are using? I have an ECU that came out of my 964 after it suffered similar problems to yours, although the problems with mine turned out to be wider than just the ECU (my ex-specialist missed some heat-damaged coils). I'm keen to check out whether it's economical to have it repaired.

Thanks
 
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