1G ECU, MPI relay problems...

[jo_91gs]

got my car running finally and now i found out that it wont crank unless i ground a certaing wire from the fuel injection relay (efi relay). i have no idea why but do know that the wire splits into 2 wires before going to the ecm. and now the interior dome lights, or the air conditioner wont turn on all of a sudden. maybe its the ecm but not sure. so i would appreciate any information possible to figure out if its a short or not.

 

[luv2rallye]

Non-starting problem sounds like ECU unless the 2 wires to it are broken. Check that and ECU for leaking capacitors inside. The lights and A/C is something else.

 

[steve]

The ECU could be dead and the engine will still crank. It won't however fire or run.

If your going to talk about wires to the MPI relay or ECU it helps if you tell us which, by pin number, function, or wire color. Since you know which wire you grounded to work around the problem, tell us.

It's very common for the capacitors to leak and damage the circuits for the MPI relay or fuel pump. Like my friend luv2rallye suggested, pull it and check.

Steve

 

[jo_91gs]

thats right, it'll crank, but wont fire. The color of those two wires are black with blue stripe in case that helps.

I still think its a short somewhere in the ignition 'cus the car rev stumbling and the lights (head, dash, etc.) are synchronized. I'm gonna take a look at the ECU for those leaks and damages.

Thank for the advice its always appreciated.

 

[steve]

The color of those two wires are black with blue stripe in case that helps.

ECU pins 63 and 65 have black wires with blue stripes that run to the MPI relay pin 8. If you ground this pin the MPI relay turns on. That's what the ECU does when it sees ECU pin 110 go to 12v. Leaking caps can damage this and then the ECU never powers up.

The dome lights could be as simple has bad door switches. Try wiggling them.
The AC doesn't nage to be related either. It could be low freon.

Steve

 

[jo_91gs]

Well I finally opened up my ECU and found out that it does have those damages around the capacitors (leaks) as described to me by one of the members. I got a hold of another used ECU of the same year for meanwhile and also took a look at the inside and found the same thing but slightly less damages.

I tried it on anyway and turns out it works a lot better too. no rigs, no MPI relay and ECU sticking out of the console, but i know its only a matter of time before this ECU goes out on me too.

So i need some help finding a new or rebuilt ecu somewhere to possibly send my ecu to get rebuilt. I drive a 91 2.0 n/t.

 

[jo_91gs]

REbuilt ecu by steve.

 

[steve]

Since you revived the thread, is it still working well?