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Forum nameEngine Management Systems & Controllers
Topic subjectECU Diagnosis
Topic URLhttp://forums.2gnt.com/dcboard.php?az=show_topic&forum=54&topic_id=5536
5536, ECU Diagnosis
Posted by gabureiru, Dec-31-69 06:00 PM
Hello all, I've been having trouble with my car (1995 GS). I'll explain what has been going on. I did an engine rebuild, but still the car sometimes idle down and died. I went ahead an changed the Crank Sensor, since the sensor was cracked I thought "I'm on the right track" I had to cut and put the new plug. The car worked fine for like a mile, then it stuttered and died. Took it home, left it there for 3 days. On the fourth day, it didn't start. But if I gave a little knock on the ECU, the car started. I didn't want to use it like that, so I went ahead and bought a used ECU, the car still doesn't start. The electric guy tells me I need another ECU, is there a way to diagnose the ECU to know if that is the problem?

Thanks in advanced....
5537, RE: ECU Diagnosis
Posted by j2sw, Dec-31-69 06:00 PM
Make sure your sensors do test out good. I had a bunch of problems with my 98 until I replaced the Throttle Position sensor.
5538, RE: ECU Diagnosis
Posted by gabureiru, Dec-31-69 06:00 PM
The electrician told me that all sensors tested out good. Honestly I don't believe him since the ECU was taken from a working car.
5539, RE: ECU Diagnosis
Posted by SilvrEclips, Dec-31-69 06:00 PM
Check for the basic things like fuel and spark. Do you hear the fuel pump priming when you turn the key on? Are you getting spark. These are easy things to check that might help narrow down the problem.

Also some different years had a different pinout at the ECU so you may have bought one that is not compatible.
5540, RE: ECU Diagnosis
Posted by gabureiru, Dec-31-69 06:00 PM


The pinout, I guess, it should match, since I used WinCAPS to match the part number to my car.

When you say, check for spark, what do you mean?
5541, RE: ECU Diagnosis
Posted by SilvrEclips, Dec-31-69 06:00 PM
Pull out a spark plug, connect the wire to the wire like it normally goes. Hold onto the rubber boot for the plug and touch the bottom of plug to something grounded. So when you try and crank the car the plug should spark. If it doesnt your not getting any spark. Dont touch the plug or it will shock you.
5542, RE: ECU Diagnosis
Posted by gabureiru, Dec-31-69 06:00 PM
Dang, cool test option. What should I do next in case there is no spark?
5543, RE: ECU Diagnosis
Posted by SilvrEclips, Dec-31-69 06:00 PM
Well if you also check to see if the fuel pump is priming. If neither pass the test then more than likely the ECU is keeping the car from running. If it detects a problem it will not run the fuel pump, injectors, or coils.
5544, RE: ECU Diagnosis
Posted by gabureiru, Dec-31-69 06:00 PM
Sadly I found no spark, and the fuel pump is no priming. Does it mean tha the ECU is bad, or is it a sign that something else is wrong?
5545, RE: ECU Diagnosis
Posted by SilvrEclips, Dec-31-69 06:00 PM
The ECU turns all of those things on. So more than likely the ECU is not allowing them to turn out. Meaning that the ECU is detecting something is wrong. It could be a bad ECU, or it could be the ECU not seeing the crank sensor, tps. There is lots of things you need to check and test.
5642, RE: ECU Diagnosis
Posted by 96TALON420A, Dec-31-69 06:00 PM
were can you find a good used or a new ecu? I have the same problem it sounds like! all my sensors look to be in decent condition but i do get spark and the cars runs for a mile or so then shuts off.
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