A friend had stored their E36 M3 3.0 with me for month or so and I went to start it today. It cranks over fine but wont start. The owner says it used to do this but only intermittently and always started on the second or third go.
Here is what I know...
There is no spark and the fuel pump isn't running, neither when you turn the ignition on or when you crank the engine.
The fuel pump itself is working, verified by powering it directly from the fuse. Crank sensor has now been swapped with one from a running car and it isn't that.
Main relay has been bench tested, its fine. Also checked all four small relays either side of the main one, as I think one or more of them are for the fuel pump. They are fine and power is present where it should for these relays.... its just there is no signal being sent to the main under ignition on or cranking and there should as far as I understand.
It seems the DME/ECU sends a ground signal to complete the circuit at the main relay thus allowing power to flow through the main relay to the fuel pump relays etc. This is not happening!
I have checked what pin on the DME/ECU this signal is sent from (27) and done a continuity test between that and the relevant terminal of the main relay. This is fine too!
So I am assuming the ERM is for what ever reason not sending this earth signal to the main relay. It could be related to the EWS 2 but i dint think it would crank if it was an EWS problem?
I looked at the DME/ECU and it looked like it had been opened before as some of the tabs were snapped off and pry marks were present. Ive opened it up and had a look, seems to have some marks that could have been water that dried on the aluminium case. Did a long and careful inspection of the circuit boards for any burn marks or evidence of a short.
No sign of anything obvious, i did clean the boards with some mild contact cleaner and a cotton bud, dried it using warm air a gun and left it for few hours before reassembling. I dint expect it to help....and unfortunately it dint!
Either its a faulty ECU or it isnt getting what it needs to deliver the signal(s)...any ideas where to go from here would be greatly appreciated
At this point I could replace the ECU but I know there is some issues with the coding for the EWS unit. Can someone tell me what needs to be done to replace an ECU ?
Thanks in advance!