94 Civic EX - Only starts if ECU is unmounted and unplugged
#1
94 Civic EX - Only starts if ECU is unmounted and unplugged
This 1994 Civic EX has me stumped.
CEL light stays on solid, indicating an ECU problem. Car will turn over, but not fire.
If I remove the ECU (unmount, unplug), then replace it, the car fires up and runs fine.
Two hours later the car will still start and run fine. Four hours later the car will start and run fine.
After sitting overnight, ...it won't start! So I repeat the ECU unmount / unplug, and it starts right up.
Unhooking the battery does not work. Unplugging the ECU does not work. Unmounting the ECU does not work. Only unmounting and unplugging works.
Does anyone have any idea is this happening ?! This is driving me insane.
Any help appreciated.
CEL light stays on solid, indicating an ECU problem. Car will turn over, but not fire.
If I remove the ECU (unmount, unplug), then replace it, the car fires up and runs fine.
Two hours later the car will still start and run fine. Four hours later the car will start and run fine.
After sitting overnight, ...it won't start! So I repeat the ECU unmount / unplug, and it starts right up.
Unhooking the battery does not work. Unplugging the ECU does not work. Unmounting the ECU does not work. Only unmounting and unplugging works.
Does anyone have any idea is this happening ?! This is driving me insane.
Any help appreciated.
#3
Re: Most queer ECU problem. Please help!
Moisture/condensation effects the capacitors on the ECU circuit board where they will work intermittently before they eventually totally fail.
Especially capacitor C14 on the circuit board that effects the fuel pump priming.
I think your removing and reinstalling the ECU creates enough vibration that disturbs the caps enough that they work. Next time just try tapping on the ECU with a wrench to see if the vibrations activate the cap rather than totally removing the ECU.
I have a damaged P28 that I'm going to bring to the electronics repair shop and get C14 and the other caps replaced. I don't know if it's totally cost effective but I'm more curious than anything to figure it out.
Good luck.
Especially capacitor C14 on the circuit board that effects the fuel pump priming.
I think your removing and reinstalling the ECU creates enough vibration that disturbs the caps enough that they work. Next time just try tapping on the ECU with a wrench to see if the vibrations activate the cap rather than totally removing the ECU.
I have a damaged P28 that I'm going to bring to the electronics repair shop and get C14 and the other caps replaced. I don't know if it's totally cost effective but I'm more curious than anything to figure it out.
Good luck.
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crookson speed
Honda CRX / EF Civic (1988 - 1991)
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02-19-2014 01:32 PM