Random Stalling ECU?

johnk · 09-26-2004, 03:52 PM

As the title suggests I get a random stalling. The only thing I notice is that there is a click under the dash and it goes out, it's like I shut the car off. I have already done the ECU caps so I'm not sure what the problem is now. It only happens like once a month and the car will stay dead for like a half hour and then be fine. I usually open the ECU case and stick it near the floor fan. This time I had fresh batteries in my palm so I checked the CEL codes. It came up with fuel pump relay. I was skeptical about it being that since the car will still start but then die when it's in the half hour window. So I ran the pump relay test and the pump clearly comes on it's loud enough when the engine is off to hear.

Do you guys think the ECU is crapping out again? If so is there a shop that repairs these? Or what alternative ECU replacements are there out there I wouldn't want to spend more than a thousand.

steve · 09-28-2004, 04:44 PM

Quote:

Originally Posted by johnk

The only thing I notice is that there is a click under the dash and it goes out, it's like I shut the car off. I have already done the ECU caps so I'm not sure what the problem is now. This time I had fresh batteries in my palm so I checked the CEL codes. It came up with fuel pump relay. Do you guys think the ECU is crapping out again? If so is there a shop that repairs these?

The click is the MPI relay, you say car won't restart for a while after but running a fan on the ECU helps? Have you tried using your logger while the car won't start?

When you changed the caps was there any leakage? If so what did you do to clean and neutralize it?

Not shown on the factory circuit diagrams I've seen but shown in the 1G tech manual is the fuel pump power sense from the MPI relay pin 2 going back to the ECU on pin 13. If the ECU senses that the pump's power turned off on it's own you get a 42 CEL. That could be caused by a bad MPI Relay, a bad ECU, bad power, etc.

Steve

johnk · 09-29-2004, 06:22 AM

It does come up with a CEL code of 42 when it stalls. I have changed the caps. There wasn't any real damage when I took them off. There was a little bit of brown goop under them but the board wasn't burnt or melted from it. The weird part about the CEL 42 is that when it happens I can run the fuel pump relay test and the pump comes on. Where's this relay so I can replace it.

Thanks for responding I thought I wasn't going to get help on this one.

steve · 09-29-2004, 10:10 AM

That brown goop was electrolyte that leaked out of the caps. It has to be cleaned off and neutralized when you change the caps or it will eat through the copper and solder.

The MPI relay is on the right hand (passenger) side of the center console on the inside down by the ECU. It has two seperate relays inside both controlled by the ECU, one powers the MPI circuit and the other powers the fuel pump.

When you hear the click does the CEL light come on for 4 secs and go off like at startup.

Steve

johnk · 09-29-2004, 10:37 AM

OK this is how I can tell when it's going off. I have the ghetto rigged knock sensor hooked up from before I had my datalogger. It reads the output for the BCS. It blinks at startup and goes out. If the ECU has power and the engine stops running or isn't started it will stay lit. When the car stalls the light comes on. Last time it started blinking rapidly along with the clicking under the dash until it finally gave out.

The capictor goop I wiped the goop off and did nothing else for it.

Are you asking about the CEL for 4 seconds when I am having the problem? I'm not sure I think it must stay on cause I get the code 42 in the logger, but never checked. I think all my lights come on. Also my brake light comes on when the car stalls...is that normal?

steve · 10-02-2004, 10:12 AM

Quote:

Originally Posted by johnk

Are you asking about the CEL for 4 seconds when I am having the problem? I'm not sure I think it must stay on cause I get the code 42 in the logger, but never checked. I think all my lights come on.

Yes, I asked that because if the ECU is resetting because of power or cap problems the CEL light will come on just like it does when you first turn the ignition on. Since you have a CEL it might not go off.

If all you did was wipe the electrolyte off you may still have issues related to the old caps leaking.

Steve