Bri Bro

Pop open the DME connector shell and look at those pins, as I remember, the grounds are shared using jumpers wires between the pins. Sounds strange one would be open, maybe you have some damaged pins on the connector. Check your PM, I need to send you a DME/KLR document.

V2Rocket

I just opened the connector, found wire for pin 28 (the open one), cut it, ran a length of wire from the connector side to the body in the engine bay. Now there is acceptable continuity (<1 ohm) on that pin but still no spark. I can't imagine how much gas I'm wasting just blowing it out the tailpipe.

However I have a feeling it still might be ground related as I noticed when you turn the key to ON the MPG gauge swings over to the left all the way which it shouldn't do since the car isn't running. Also the oil pressure gauge as I crank it increases as it should but then will suddenly fall to 0 and then go to 1.

Really starting to wonder if I should just remake the entire wiring harness.

Bri Bro

I would trace back the ground wire you cut to the source. Maybe other grounds share the ground on that wire. Sent you the test plan, let me know if your can download it.

V2Rocket

I got impatient and went back into the DME plug and found wire number one which according to my DME plan is the ignition pulse signal. I had previously deducted that there must be a short somewhere in the length of the green wire so I cut it a few inches from the DME plug and put a new wire in all the way to the coil. Still no fire.

Looking at how the wiring is routed, a question came up: is the DME relay in any way in charge of ignition? I can't find any information about it in my diagrams, they all make it out to be just a fuel pump relay.

Another question, where does the black wire that goes to the coil get power from?

I just finished working for the day and have been at it since about 630 this morning, and I am pretty disheartened to say the least. I will admit I spent a few minutes on Vitesse's site pricing out their coilpack system...

Bri Bro

The 12V to the coil is directly from the ignition switch. The DME relay does control power to the DME. I have to reread this thread...I thought you could not get spark even if you grounded the coil with the ignition on. Are you sure your 12V supply is good?

driftwood

Have you checked the pins on the connector?

I have a similar problem with my 86 951 and so far have only traced it to the wiring right at the connector. I could only get mine to run by tapping the floor near the DME/KLR or duplicate the issue by wiggling the wire harness near connectors.

Aside from many other things, I did drag tests on all the DME connector pins to no avail. Doing a wiggle test on the harness at DME while running caused it to stall/sputter so I took the conn apart to pull test each wire. Found nothing wrong. Plugged conn in while apart and ran car pulling on wires individually, still inconclusive.

I even took the DME apart as I read on here somewhere the solder joints go bad, though I didn't see anything wrong in there, you might want to check that.

Without having a full day to deal with it til winter, I jerry rigged it for now. I put the conn back together and zip tied the bundle every inch or so for a few inches away from the conn, then manipulated the harness to have downward pressure into the DME.

I'm certain a wire is damaged inside the sheathing, but this has done away with my intermittant no start/sudden stall for the last few months. This winter I will go back and run continuity tests on the wires once I get the pinouts/wire diagrams.

If you have access to a terminal test kit, I would drag test the conn. Do a wiggle test on the harness while trying to start the car and or tap the floor or lightly tap the DME while trying to start.
Good luck.

Joe

V2Rocket

if i remove the coil from the car and hook it up to the battery directly on + and - sides, and ground a spark plug too, it will make a spark. but in the car it doesnt.

i know i have 12v at either side of the coil but not sure if that's "good". maybe ill run a new wire from the switch to the coil.

does the green ground wire from the coil go directly to the dme, no switches relays or anything? thats what my diagram tells me but like i said i ran a wire the whole way to the back of the DME plug and it didnt work.

Bri Bro

Yes, the coil (-) wire runs directly to the DME. I would like to see you connect the coil 12V side to the battery. You could also measure the 12V at the coil with one side grounded, it shouldn't change much. Do not ground the coil for more then a few seconds, it is pulling around 15 amps though a small wire and the wire will get hot.

V2Rocket

So you think that running a wire from the battery directly to the coil on the positive terminal and a wire from the negative terminal to to DME might work?

Bri Bro

Worth a try. You might start by running a wire from the battery to the coil and see if you can generate a spark when grounding the coil.

Dougs951

Hey Spencer- I had to steal your Avatar idea for a bit.

V2Rocket

spent the day looking at grounds and sensors. removed the intake, removed the engine block grounds, cleaned them up, new neg batt cable, checked ref/speed sensors, ran a wire directly from the battery to the coil +, threw it all back together anddd nothing.

fwb42

Just a little off the wall thinking,but have you checked your ignition switch? Switch connectors?

V2Rocket

switch that was in the car when the car died was about 2 years old, put a new one in a few days ago for good measure

but it couldnt be the ign switch since completely going around the switch by hooking the coil directly to the battery didnt get any spark.

the only thing that i can think of now is that maybe the allen screw in the flywheel is gone. that will have to wait til the weekend though.

V2Rocket

what ive done/replaced:

-DME relay
-DME
-coil
-ignition switch
-removed and inspected speed/ref sensors, replaced speed sensor.
-tach is bouncing.
-getting fuel from the injectors.
-have removed and cleaned DME grounds at the bellhousing and firewall,
-also body grounds on frame rails,
-replaced battery neg cable,
-cut out factory ground on pin 28 (no continuity) and ran a new ground wire
-gone into the dme plug, run a new wire straight from pin 1 all the way to the coil (-),
-run a new wire directly from battery (+) to coil (+)
- no alarm is on the car
- after the car was all back together, connected a sparkplug to the coil wire and tried
to get spark with someone cranking, nothing.