Here we go with the basic information......

1988 951
Sat all winter
Started up and drove multiple times this spring with no problems
Sat for a couple more weeks and now it won't start

Cranks, but does not fire.
Has tach bounce
Fuel pump runs, did not actually test pressure (don't have the right adapter)
I've gone through most of the diagnostics in the factory shop manuals (no oscilloscope) and Clark's garage troubleshooting
bypassed factory security - still nothing
wiggled, cleaned etc speed and reference sensors

I've pretty much come to the conclusion that the DME may be bad / bad solder joints. I am willing to spend the $$$$ for a replacement as long as I know that it will fix it.

Is there anyone in the Parkersburg, WV / Marietta, OH area who would allow me to borrow their DME to try? Or willing to come hangout, drink a few beers and help me get this thing running again?

Thanks in advance!

 

I have a spare DME from an 86 (24 pin) and also have an 86 DME that is converted to 28pin, but im a good five + hours away from you. did you check for spark? could it be coil / distributor related?

 

did you try new plugs?

 

I did not try new plugs. I eliminated them by checking for spark upstream. I really don't think that's the problem as it doesn't even attempt to fire at all.

I pulled the cap and inspected the rotor etc and it all looks fine. I suppose it could be possible for the coil to be bad. I think I have a spare around.

I may just package the DME up and send it to ECU Doctors and have them test it. $50 could save me a lot of headaches.

 

Have you tested if the plugs are getting spark? And if the injectors are firing? DMEs (and KLRs) go bad, yes, but it's generally low on the probability scale for random no start situations. You say you confirmed spark further up the line. How/where did you check? The injector harness is also a common failure point -- have you tried shaking the harness while someone cranks the motor? Also the bell housing grounds and fuel pressure. No harm done sending DME to ecu docs for testing, they're great, but might be quicker to narrow it down more if it turns out to be something else.

 

I checked at the plug wire with a spark tester. The injector harness is a Lindsey harness and only a couple years old. It still could be a problem though. I do need to get an adapter so I can check the actual fuel pressure.

Thanks for all the ideas.

 

Did you have spark checking that way?

 

No spark. I've never had spark during this whole diagnostic. That's why I'm not so concerned about the actual fuel pressure.

 

I see. So have you checked if the dme is getting power. The most common failure is a bad dme relay.

 

Yes, swapped relays. Jumpered the terminals at the fuse block to activate the fuel pump. Checked for voltage at all the test points in the service manual.

I will go through factory service manual step by step again. And if I don't have a solution by Monday I will probably ship out my DME.

 

Sounds like you are testing methodically. You might back up and test for a pulse at the coil wire connections to rule out a bad coil. Have you also tested if the injectors are getting any pulse?

 

I just went and got a set of noid lights to test the injector pulse.

This chase reminds me of when I put the engine in the car.

The car is actually a 1990 S2 with a 1988 2.5 Turbo engine. There are slight differences in the body harness that had us chasing wires for awhile.

And yes, I've checked them too!

 

If you get an injector pulse but no spark at the plugs, be sure to check for a pulse at the coil and/or swap in a new coil to test it.

 

+1

if no spark there, bypass the KLR then try.

 

Agreed!