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EJ swap -> fried ECM?

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85 Brat

92 ECM & harness

97 EJ22

 

Finally got to the point where I tried to crank and it turned over but I had no CEL and no fuel pumping - like the MPFI system isn't coming on. I checked over my wiring again and found only 1 mistake: I had put constant 12V to the MPFI diode instead of ignition switched 12V. I've fixed that, verified I have voltage at the ECM & ignition relay, checked all my grounds and tested the ig relay and fusible with a multimeter.

 

ECM came from the junkyard but I have yet to get a bad one. I'm not sure how to see if this one is toast or what else to check.

I'm thinking the ECM is not compatable with the motor. 92 was way before OBDII and a 97 engine would definately be OBDII. They just aren't communicating with each other properly.

  • Author
I'm thinking the ECM is not compatable with the motor. 92 was way before OBDII and a 97 engine would definately be OBDII. They just aren't communicating with each other properly.

 

97 longblock, 95 intake, 92 ECM & harness

 

I put a 92 TB on there (for the TPS) and 92 cam/crank/knock sensors. I'm using a 92 MAF and will be using 92 O2 sensor. I wired in the 97 coilpacks, common upgrade. Everything that matters is OBD I.

 

There should be no compatability issues, none that would cause this scenario at least.

You say no fuel is pumping. Is the fuel pump fuctional?

Check both the yellow wires going to the Ig. Relay and make sure they have power.

  • Author
You say no fuel is pumping. Is the fuel pump fuctional?

 

It was feeding the SPFI engine in there weeks ago just fine.

Are you maybe dealing with different generation cam sprockets that is creating some kind of incompatability with the cam sensor?

  • Author
Check both the yellow wires going to the Ig. Relay and make sure they have power.

 

Both have 12V from the battery. I verified I have 12V out the other side when the relay is on and I have full power at the ECM connectors:

 

constant 12V to B48 pin 15 (back-up power)

 

12V in run & start to B48 pins 2 & 13(power supplies)

 

12V in run & start to B58 pin 12 (ignition switch)

 

12V in start only to B56 pin 10 (start signal)

 

Gounds have good continuity, voltage is there...:-\

  • Author
Are you maybe dealing with different generation cam sprockets that is creating some kind of incompatability with the cam sensor?

 

Even if I were I think I'd have a CEL and fuel pumping right? I'll see if I can find tone patterns.

Even if I were I think I'd have a CEL and fuel pumping right? I'll see if I can find tone patterns.

 

Yeah, youd have CEL and Fuel Pump operation for at least a moment.

 

Plug in the test connectors, does the fuel pump cycle?

 

One thing I did mistakenly on my first swap is I wired the output to the fuel pump from the relay.........directly to ground:eek: It's a black/red wire......all the other black wires in the swap are grounds and I mistakenly thought that wire was the FP relay ground. "Yeah......the Black/red wire from teh relay is POWER, not ground.....note to self."

 

Sorted it out and it was fine.:confused:

When I did my wagon's EJ swap, I couldn't get it to start until I swapped ECMs. I don't remember what part of the system wasn't working.

 

Get another one and see what happens if you swap them; you can always return the extra if it turns out not to be the cause.

Ah the joys of a swap cobbled together from numerous cars with unknown history.

 

It could be many things, the ECUs are pretty tough to fry, but not impossible. If you've got a spare, try it. but I'd pin out every wire before buying one.

You could plug yours into a known running car, I don't know if Id try it the other way though.

  • 2 months later...
  • Author

I replaced the ECM, re-ran all MPFI power through a hidden toggle switch, added some grounds under the dash and now it runs beautifully. The previous ECM will not turn on so it must have gotten fried at some point. Exhaust and radiator work to come soon...been spending too much on the Ramcharger...

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