Phil Harrison

I'm having an intermittant problem that is confounding my diagnosis skills. The car is my away from home car near my customer 800 miles from home & I have minimal access to tools & parts...

Car is an 88 951 (non-S), mods are Guru chips, boost enhancer & an aftermarket alarm.

Drove car to parking lot, left it there 4 days, came back - failed to start. Found no spark at coil output...

Read up on Rennlist & clarks garage, suspected DME relay. Bridged terminals 30/87/87b, still no start, Tachometer flickers (so speed & reference center are OK?). Boost gauge is at 1 with ignition on.

after cranking for 60 seconds starts & stalls. Try again & again...finally starts & goes.

Drive for 30 miles - perfect.

This morning , starts fine, drives for 10 minutes, then cuts out completely, (there was still a tacho signal on coastdown with ignition on). Car stops, put back DME relay by-pass, still no-start.

Wait 10 minutes, fires then stalls, repeat twice. After 20 minutes, restarts & managed to drive to work.

It's as if something fails intermittantly & cuts the power to both the fuel pump & ignition. Anyone have any ideas?

TIA

944Ecology

Hi, Phil,

Probably a bad DME or KLR.

If you have driven the car with the jumper (in place of the DME relay), it removes the relay from the equation.

Also, there have been a lot of failures of the alarm control unit lately...

gb

xsboost90

ok, dont know but mine has refused to start on occasion. The wires coming from the rear of the intake that go to the reference sensors have two plugs that are on a braket at the rear of the intake itself. Where they connect, i guess they get corroded etc. ... wiggle those two wires and see if it starts. Everytime mine does that, i wiggle the wires, and WHALA! it starts.

Chris_924s

XSBoost got it first! Yep- sounds like speed and ref sensors connections may be in need of attention.

Rock

Sounds like what happened to mine when my Speed sensor went to hell. It drove, but eventually it just crapped out and died after i parked it.

Phil Harrison

Doesn't the fact that the tacho still pulses show that the crank sensors are working?

Jim @ EuroWerks

That would make since, wouldn't it. So, while the car is not starting and you have no spark, how is everything else. Do you have pulse to your injectors? I usually start with cking both , so if either is working (spark or injection pulse) you know the speed & reference sensors are working fine. Just recently we ran into the dreaded broken solder joint in a DME. When you wiggle the DME plug the car would start. So, ck both and let us know what you find and we'll help you from there. Also when you ck for spark, ck it at the coil wire so if the rotor or cap are failing you won't get confused.

Justin Browning

If the wiggle doesn't work, try a slight tap on the plywood over the DME. That worked for me.

Phil Harrison

George, Danto & Justin have it!! Cross posted from Turbo forum:

Danton, I think you have it

On Friday afternoon, wouldn't start again. Hit the plywood that the DME mounts to & she started straight away!! I've got a DME & KLR coming from Turbo Tim, once they are installed I'll take the one in the car apart & see if I can spot any bad joints.

Thanks all for your help - Rennlist Rules!

MHT

if there is a problem with the ecu, I suggest looking at the points where the ignition driver attatches to the board. you will need to remove the cover and the bottom alum. plate also, the ign. driver is the quarter sized round unit mounted perpendicular to the board, there are three traces that connect the driver to the board, quite often, the solder joints on the back side of the board will crack. I have also seen cracks where the traces connect to the three pins coming out of the driver. If any of the connections look the least bit suspect, re-solder them all and see what happens. My preference would be to disassemble and fix your current ecu rather than replace it with an unknown unit.