adrian1

I have a 86 951 here with a no start issue, wiring harness was shot as always so i rewired it and also changed the speed sensor to a new bosch one. I found it destroyed due to wrong gaping. Both sensors are reading 1k ohms.

1.) Harness rewired
2.) New Speed sensor and now both have 1k ohms
3.) I do get spark and fuel when cranking but no tach bounce.

P.S. I do have another running 86 951 here to swap parts from if i need to, prefer not to...

I was wondering if I can hard wire both harnesses to one sensor and see if it starts..?

Rogue_Ant

No.

Turbodan

did you try swapping ECU?

adrian1

Ok thanks!

adrian1

I will first Bypass the KLR, then if it does not start I will take the DME out of the other car and see if it starts. This car is driving me nuts!

Will Feather

Heres some great info from ECU doctors, (they are on here), about testing the speed and ref sensors at the harness into the ECU

http://www.ecudoctors.com/home-porsc...nsor-test.html

adrian1

Both resistances checked out OK at the DME plug. So no broken wire. Now going to bypass KLR.

adrian1

Jumped pins 9 and 16 on the KLR and still no start, and no tach bounce during cranking. Going to switch DMEs now........

adrian1

Put the DME from the good running car with no luck, don't have an o-scope. I am out of ideas..........

Anyone?

adrian1

Ok, only get spark and signal at fuel injectors in the split second when you stop cranking with the starter and the engine is still rotating(split second). So basically when cranking theres no injector signal or spark, but when off the starter even the tach bounces a bit.

Will Feather

New DME relay? Or jump it?

adrian1

I never bothered changing the relay because i tested for both DME power supplies and they have power constantly key on cranking or not. Now will try from a push start bc it seems when the starter is engaged it stops spark and signal to the injectors......

kev951

speed reference sensors cris crossed? wrong plug to to wrong sensor? .. when you say rewired the harness.... what exactly was done.... ?

adrian1

I cut off a section that was shorting them out and put in new wires all color coated like factory. Tried sensors both ways. Car did not start from a push start. But for some reason when letting off the key to start it the spark plug that I checking with will spark once and niod led light connected to one injector will blink once or twice. I am really out of ideas...........................

931guru

Time to take it to a mechanic who knows 944 turbos.