max_boost951

'86 951 has been having running problems for at while now. Car cuts out around 4000 rpm at W.O.T. Its fine when you stay out of full throttle. 80% throttle and the car runs fine. Have a manual boost controller and Dual Port Adjustable Waste Gate with a Wideband O2 sensor for tuning purposes.

Items that I've checked:
TPS
Air Flow Meter
Swapped with know good KLR
DME/KLR chips
New Plugs
New cap and Rotor
Replaced all Vacuum Lines intake gaskets, throttle body gasket
ohm checked injectors
ECT sensor
65 psi fuel pressure at WOT
Have trigger at the coil at WOT
I've checked all grounds coming from the DME and KLR

I find it weird when you go WOT the wide band oxygen sensor reads 10.8:1 AFR then around 4000 RPM AFR goes to 16.5:1....oxygen sensor lays fat the entire time even through the range at 860mv.

I just found these wires on the back of the camshaft housing. Does anyone recognize these wires...they looked like the have been blatantly cut. see pictures... Really need help with the solution

Jeff N.

Can't ID the cut wires.

I had a similar problem and it was a coil on the way out. Didn't have enough cajones when the boost was up to fire the plugs. If you have a buddy near by with a 951, try swapping.

max_boost951

I swapped a coil off another 944...problem still persists. Has to be firing cause the air/fuel ratio.

blown 944

Have you tried closing the plug gaps?

max_boost951

I will try that...but how will that effect this problem?
Air/fuel meter shows ignition system working.

blown 944

Afr gauges can play tricks when there is an overly rich issue. I remember u was having stumbling issues and my wb kept showing a totally lean condition when in fact it was going excessively rich. that was with a different wb than I have now but it happened and was strange.

max_boost951

what should i close the gap to?

blown 944

I run mine at .025

schip43

It sounds like a boost leak, that is exactly what mind did, when the TB to hard pipe coupling blew off. Additionally it made a sound like a waterfall. Steady state it would cruise fine but no acceleration. It looked good but it would blow off, I replaced it and that took care of it.
Just a thought.

max_boost951

Changed my gap to .024. Problem still persists. Open for more suggestions

Willard Bridgham 3

Check all air pressure connections with soap/water solution.

fast951

Have you verified that the DME is getting the "Full Load/WOT" signal? You can check it with a multimeter by probing the pin at the back of the DME connector (you'll need to remove the plastic cover).
If you are getting the WOT signal, then check the Idle signal at the DME. Make sure you are not getting both signals at the same time (Under WOT there should be no Idle signal).

Can you monitor the AFM signal? It's DME #7 and should have a 0-5Vdc signal..

Is the problem affected by boost? Does the 4000RPM marker changes UP/DOWN based on which gear you are in? Can you go over 4000RPM under PT, then go to WOT?

Of course, with the DME connector apart, examine the wires, make sure no wires are exposed...

max_boost951

I cannot go over 4000RPM under WOT, I CAN go over 4000RPM under PT but will cut out at WOT. I will recheck the the TPS and AFM signal and return with the results.

P.S. I can turn the boost down to around 9 lbs and it will run better and not cross-check me into the steering wheel as bad.

max_boost951

Car needs a DME!!!! Swapped with a known good problem solved....
QUESTION: 4-5 years ago i put a DME in the car, Don't know why it went bad. Then the new DME went out within a week. Bad fuel injector harness. Replaced harness and replaced under warranty a DME. Now 2 years later needs another DME. Could a piggyback fuel controller cause these issues? What is killing the DME's?

Bri Bro

Lets see:

Water leak from battery tray. At first, the water isn't a big deal, it isn't that conductive but over time it goes into solution with other chemical on the board and then it can conduct.

Running high duty cycles with bigger injectors without the in-line resistors in the injector wires.

Cracked solder joints around the large large driver transistors in the DME due to temperature cycles over time. They can be fixed, several post on this.