Once again, I find myself at my wits end with the '86 951. Over the last 5 years, virtually EVERY electrical component, fuel system component, and ignition component, has been replaced on this car. I defy anyone to try and identify a component that is often, or sometimes associated with intermittent stalling, that I have not replaced, or had checked out by a professional (e.g., ECU and KLR). I still will have an occasional, random stall. Usually happens at steady cruise, engine just shuts off. I can simply, push in clutch, turn the ignition off and on and it restarts immediately and I keep going. Sometimes I can go days without any problems. Other times it will cut out a dozen times in an hour. No rhyme or reason.

The only think that I can think of now, is the ignition switch. However, I will say that I never have a problem with it cranking or starting. It is only a cut out while driving. Has anyone experience anything like this with an ignition switch?

I'm scheduled to do a DE at Road America next week with my son. I really want to drive the 951 (and so does he!). I'm open to any suggestions anyone has. I have been through EVERYTHING I can find on the forums and so far, the problem remains.

Thanks.
Roger

 

You say you have changed virtually every electrical component. Does that include replacing/rebuilding the engine wiring harness?

 

Just a shot in the dark here, but do you have an alarm system in the car? I bet you already looked at this as a possibility, but if not.....

I am saying this because I am currently dealing with an issue of non-starting myself, and my mechanic is looking into this as a possibility.. (his idea, not mine.)

 

Sensor harnesses and the fuel injector harnesses. These were cracked and causing intermittent stalling, i.e., you could wiggle them and get the engine to stall. Replacing these was a big improvement, but still didn't solve the occasional stall.

Roger

 

No alarm system. My car starts fine every time, even after it stalls.

Roger

 

Did you check the 15 power relay? It's the big 40 amp one in the fuse box. I forget which position it is in.

 

In my fuse box I think that is G2 - Ignition Relay. It is actually a rather small cube, the same as the fog-light relay and the horn. I swapped it with my fog-light relay. Can't hurt. Thanks.

Roger

 

I'm pretty sure I replaced the DME temp sensor last year, but if the sensor wasn't working properly, I wonder if this would suddenly change the mixture enough to make it stall? It only seems to happen after the engine has warmed up a bit. If the temp sensor suddenly tells the ECU that the engine is cold, I assume it would enrich the mixture. I do notice that sometimes when it dies it also backfires out the exhaust, which could be excess fuel passing through. I might be grasping at straws.

Roger

 

I just checked the DME temp sensor. I now remember that the female harness/connector is cracked, so that there is no metal retaining clip. I can press it on, and it appears to stay in place, but I could see where this could vibrate loose over time and potentially lose contact with the male terminals on the sensor (which was replaced last year).

I assume if the sensor loses contact it is equivalent to a "full cold" temp reading?

Roger

 

I found this thread; https://rennlist.com/forums/924-931-...he-engine.html

I'm really hoping this is my problem. I tested it last night, by unplugging the DME temp sensor after the engine warmed up. The engine would barely idle, chuffing black smoke, as soon as I blipped the throttle, it died. This would make sense, with me cruising at a steady state, very light throttle, the sensor losses contact momentarily, and it dies.

Roger

 

If you are cycling the key and it is starting again, makes me wonder if it is thinking it is in overboost protection. I had a sticky problem that drove me crazy for a couple of years. Would typically stall on me when I went around corners in 2nd gear and not accelerating so overboost didn't make sense.

In the end, I had a problem with the AFM that was compensating for bad injectors and the computer indeed thought the car was in overboost. Cycling the key and it would always clear the code and start right up.

I think you should make a blink code tester and monitor the KLR for blink codes when it cuts out. One trip to Radio Shack if you can find one and you can get the components you need.

 

Please post back if that solves your issue!! I'm crossing my fingers for you!

 

I have a 951 Max chip, so no factory overboost. Refurbed AFM, all rebuilt injectors, etc. I have a blink code reader installed. Problem is that it normally cuts out on the highway, at 70 MPH, in traffic. Not a real convenient time to pull over and try to read blink codes.

Drove it to work this AM. And yes, it cut out once, at 70 MPH, backfired out the exhaust and started right back up. I did notice that for the rest of the trip in, when I was idling, the AFR ratio was pegged over to rich, instead of the normal oscillating back and forth (no, it's not a wide band!). If the DME is not receiving the appropriate signal from the temp sensor, I would expect that it might run rich.

The female connector on the harness is cracked, so it doesn't fit securely on the sensor. In addition, the wires for the sensor look pretty crappy, so even if it is making contact in the plug, it could be shorting out somewhere along the wire. I may try to rig up a new harness from the sensor to the DME plug.

It's like playing Whack-a-Mole!

Roger

 

Isn't an aptitude for playing that game a 944 ownership requirement?? It should be like a requirement to pick up the keys. If you don't score above 98% at whack-a-mole then you can't have your 944!!!!

By the way, I found something new for my sig, thanks!

 

Get a 5 foot long section of 10-14 gauge wire and put 1/4" eyelets on either end.
Next time you have this problem use this "jumper wire" to connect the battery positive terminal directly to the ignition coil black wire terminal. You'll need a wrench.

See if the car dies anymore on you...be sure to unhook the wire when parking the car.