kendo

Hi all

Hoping to get some ideas on what happened to my car today please. In bad traffic and the engine started to misfire on one cylinder, I noticed the oil temp gauge at 9pm so not excessively hot. I then started to progressively lose cylinders eventually limping to a stop on maybe 3 cylinders (as far as I can tell, no power whatsoever, it would barely move). I waited 2hrs for the engine cool and on first attempt the starter clicked but did not turn over. First horrifying thought was engine seizure which I dismissed as it was not that hot and oil level fine.

On 2nd attempt 5 minutes later the the engine turned over but did not start. I am not trying anymore until I can get it to the local specialist on Monday.

The car had a misfire for about 5 minutes 6 weeks ago but it cleared and was put down to a bit of moisture in a dizzy cap.

I don't think 6 coils, 6 injectors, 12 leads and plugs, two caps or two rotors could fail progressively so am suspecting a DMA relay or possibly the MAF (of which I know nothing about). No check engine light warning either which is very weird.

Any ideas gratefully received. The car is non varioram C2 manual.

best regards
Kendo, rennlist lurker of many years.

CalvinC4S

pull the 2nd distributer cap off and see if you can turn the rotor by hand.

I'm not as familiar with OBD1 as I am OBDII, plug a hammer in and see what happend.
OBD1 should record a misfire if that is what it was.

kendo

Thanks Calvin, if the rotor turns that would indicate the belt between the two has failed right? I guess the engine would still fire off the 6 working plugs though? Won't have access to a hammer until Monday unfortunately. What I found weird was the progressive loss of cylinders.... if something fails it normally goes completely... maybe its a fuel supply issue, blocked fuel filter perhaps...the tank was in its last quarter and the filter is not that old though...

berni29

Hi

Usually if the car just clicks and does not turn over it is a dead battery or loose battery connection. That is where I would look first otherwise how do you explain the car not turning over? I think also there are just 2 coils are there not? I would then swap the DME.

Berni

Deadeye

I'm with Berni, check battery voltage, battery terminals, ground straps.

kendo

thank you both, the car turned over fine on 2nd attempt. I will check the battery and its connections but don't think its that. My hunch is DME I but don't know if they fail progressively or instantaneously. Will the car still run if the relay is on its way out then slowly die completely or is it a bit more binary than that? If any one knows, that would help a lot.

I recall from my 964 days, rennlister's advice to keep a spare DME at all times, and its £25 fix or there abouts, fingers crossed for a cheap fix... if it is I won't leave home without a spare DME in the glove box ever again!

thanks again for help

Peter B

Make sure the DME relay you purchase has a 993 number on it. There were a number of duff 964 relays produced. Sometimes £15 on Fleabay, too
HTH

C4SJOHN

Has your engine wire harness ever been replaced? Some 993 had a recall due to failure of the poor quality from one of Porsche suppliers. I think that most of the cars were 1995 and some 1996 year models. Your dealer or Porsche customer care can see if your car is open for this recall. You will need your cars VIN number to see if it is on the recall list. I think the first thing to replace would be the DME relay if you have not done so before or if it has a 944 part number on it.......

berni29

Hi

I once came back from North wales to London on the back of an AA recovery truck because of a failed DME relay. Not that I knew it was that at the time. The DME in that instance failed over a period of time, and the car would just cut out every once in a while or just not start.

Bad earths and battery connections can be very intermittent. Maybe the extra 5 minutes was enough for the connection to cool down. Poor earths/connections can get very hot.

Berni

kendo

thank you all again for your suggestions, fingers crossed its the DME. Once I know for sure I'll add to this post to let you know, and help people in the future.

Garth S

As you do not (yet) have a spare DME relay .... no problem: pull the DME relay from the CE panel, and use some wire bits to jump pin #30 to both #87 & #87a.
Caution - #30 is always live +12V, so do not touch this to the chassis - only to the slots indicated .... and the numbers quoted are on the relay and indicate the correct male spades - use the corresponding numbers on the CE panel female slots to insert the jumper wire(s).

If you have a wire crimper, make up a proper 3-way jumper using crimp on spades.

If the car starts & runs ... viola! 5 cents worth of wire & 5 min. of your time will tell the story ..... BTW, if it starts & runs, it is also safe to drive this way - provided the jumper is pulled once the car is parked.

David in LA

Since your car is non-varioram, I'd check and see if the car already had the wiring harness replaced under the recall as mentioned above. Intermittent start/firing, some cylinders not firing, surging, etc were symptoms when the harness on my MY94 cab finally went. Happened more often during rain/high humidity days and felt like some of the spark plugs aren't firing and the car was running on only 3 or 4 cylinders, then all of a sudden the power would surge.

The times the DME relay went out on me it was more all or none...either the engine started or it didn't, it was never intermittant.

e9stibi

But the DME swap is always the best way to start. Ask me how I know ...

berni29

Hi

I had my harness done under recall just recently. The OPC who did the work showed me the old harness. It was absolutely burnt out and a mess of exposed wires on one length, and the rest of it did not look too great either.

Berni

cy7878

Kendo, where are you located? I can't believe there isn't someone nearby where you are just to borrow a DME relay to try. WHen my relay had a problem, it thew a CEL code first on my 96 with OBDII, but no misfire or stalling at all. Whereas my old VW would have stalling problems that was intermittent, but not the rough running or misfire issues. Have you considered dual distributor belt? I assume if it snaps, you get half the engine running but not the other half.... well if you are near So OC, I let you borrow my sapre relay.