asoduk

So I drove the car (86 951) home from work about 2 weeks ago, then went to move it into the garage a few hour later but it wouldn't start. The car cranks over strongly and has good voltage. The tachometer bounces just fine.

Tonight my dad and I began digging into it. I put a fuel pressure gauge on and its making 38psi. When I pull the plugs and try to start it, I smell gasoline. I would imagine that means the injectors are firing. It has a new cap and rotor on it as well as spark plugs. Plug wires are older but all test out to have the correct and consistent resistance. Tried another coil but still no start.

Used both a spark tester and a plug close enough to ground on the intake manifold but no spark.

I tried bypassing the alarm, but still just cranking and squirting fuel. I have also tested the DME relay and both ignition relays in another car and they check out fine.

I'm thinking this is something glaringly obvious that I forgot to check out. Some help from the crowd please?????? We're stumped!

fbgh2o

But are you getting spark? It might be a bad DME itself.

asoduk

thanks for the quick response! unfortunately, no spark at all.
I guess I should also note that the car is all stock with the exception of a 951Max Chip (the one meant for stock cars).

fwb42

Alex , I've got a new DME relay that you're welcome to try. I'm home all day tomrorrow if you need it.
PM me yuor cell if you need to get together.
Fred

asoduk

Thanks Fred.... already tried a few different ones and mine in other cars without the results I wanted.

User 52121

Reference sensors.

Try jiggling the wires for the reference sensors. Also try disconnecting and reconnecting them from the wiring harness (just be careful, the connectors are known to crumble from all the exposure to heat.) Jiggle first.

alxdgr8

Tach bounces fine though which would lead to another diagnosis.

asoduk

thanks guys. i have a few other cars here, but not sure if their DME's will work (with the right chip) to test: 86NA, 89 turbo, 90 S2. Any idea if any of those will work with the right chip?

951Saga

I don’t believe those DME boxes are interchangeable.
The cap and rotor are new, but have you put eyes on the rotor and checked its condition?
I’ve had a fairly new one fail before, some have hade the screw come out.

User 52121

Missed that....

Hmmm. Did you verify you have 12v at the coil?

Otherwise DME like others are saying.

mclarenno9

I had the same problem about two weeks ago as well.

https://rennlist.com/forums/944-turb...6-bad-klr.html

I had no spark because the ignition signal was not being sent to the coil. Basically what happens is the DME fires the coil every couple milliseconds by temporarily grounding it. For whatever reason this signal comes out of the DME first and actually passes through the KLR, so either one could be at fault. Here's what I would do:

1) Measure voltage at the coil with the ignition ON. You should have 12V at both of the small terminals.

2) The DME/KLR grounds the (green) negative terminal of the coil to fire it. If you put a test light in the circuit while cranking you may be able to tell if this is happening.

or

You can rule out the KLR by bypassing it. Remove the KLR and put a jumper between pins 9 & 16 on the KLR harness plug. DO NOT DRIVE THE CAR LIKE THIS! Just see if it will start. You can see the pins below:

asoduk

Thanks for all the tips guys! I now have more to check out tonight!