ecm testing

[hpaulb]

Anyone interested in testing a 924s ecm? My car hasn't started in 7 years. Replaced and tested everything. No start and not tach movement turning over engine. Ya, new speed sensors. Got another ecm from a Junker yard but the same. It's one thing i can't test on my own.

[walfreyydo]

Are you lacking fuel or spark?

[944 Ecology]

We do this as a service. No charge except for return shipping.

It might be better if you find someone on your side of the USA/Canada border so shipping is cheaper.

PM for details...

[hpaulb]

There was no 12v to fuel pump. Found 12v at ignition switch and ran a wire directly to the relay that feeds the ECM and fuel pump. Put gauge on rail and gives me the correct pressure. No tach movement on trying to start it. Got another ECM from a Porsche scrap yard with no test or warrantee. Both do the sane thing. What's the chance there both bad?

[walfreyydo]

Did you check (bypass) the DME relay? 12V signal to pump must go through the relay. See the "Emergency Repairs" section on correctly creating a bypass which will tell you if the relay is bad.
https://www.clarks-garage.com/shop-manual/fuel-05.htm

Another helpful link related to troubeshooting (hint: once you get fuel, you should check for spark, and if you have that, whether the injectors are firing)
https://www.clarks-garage.com/shop-manual/ts-01.htm

Chances both DME's (common terminology for ECU/ECM) are bad is low and I would test some of the other components first before making that assumption, starting with the DME relay (fuel pump relay), which is extremely easy if you make a jumper. Also note that the connectors for the speed and reference sensor could be old/cracked/disintegrated, wiring bad, or you may have them hooked up backwards (since there are two sensors). Speed sensor = signal for tach, reference sensor = crank position sensor.

Also, I would stay away from cutting up and running wires directly to the pump, so hopefully this was just a jumper and done for testing purposes and nothing was cut or modified permanently. That is just asking for more trouble and will make your diagnosis steps from existing resources (like Clarks) impossible to replicate.

[hpaulb]

I installed new sensors, bypassed the relay control for ECU power and fuel pump. Has to be somewhere in the electrical system or ECU itself? Have shop manual but hard to figure out the alarm portion. Relay direct power from ig switch should have taken care of that?I know i had to unhook the siren 10 years ago because it kept going off. Can't even find it. Been changing everything out to narrow it down with no results. No tach movement. That's from the ECU.

[hpaulb]

I installed new sensors, bypassed the relay control for ECU power and fuel pump. Has to be somewhere in the electrical system or ECU itself? Have shop manual but hard to figure out the alarm portion. Relay direct power from ig switch should have taken care of that?I know i had to unhook the siren 10 years ago because it kept going off. Can't even find it. Been changing everything out to narrow it down with no results. No tach movement. That's from the

ECU.

[djnolan]

have you checked out the fuel pump relay?

DME Relay Information and Testing

[walfreyydo]

Originally Posted by hpaulb

I installed new sensors, bypassed the relay control for ECU power and fuel pump. Has to be somewhere in the electrical system or ECU itself? Have shop manual but hard to figure out the alarm portion. Relay direct power from ig switch should have taken care of that?I know i had to unhook the siren 10 years ago because it kept going off. Can't even find it. Been changing everything out to narrow it down with no results. No tach movement. That's from the ECU.

Did you jumper the relay per the instructions in Clarks garage link? (you need to jumper 87, 87b and 30 together on the relay plug) Simply running a jumper wire to the pump isnt going to send power to the DME and injectors, hence no tach bounce... If you did not jumper the DME relay per the exact instructions on Clarks, I would do that and then see if the car starts. If still doesnt start then follow the engine troubleshooting guide I linked, and start checking for spark and whether the injectors are firing (assuming you have correct fuel pressure at the rail with the relay jumpered).

I really really recommend reading through Clarks Garage as it can supplement information difficult to find in the FSM and provide really great troubleshooting steps, such as bypassing the alarm.

[hpaulb]

yes. wired 12v from ignition switch to control relay.