When i picked up this 91 4runner 3.slow it had a torched ecu and when you started it it only ran off of the cold start injector for a second then died, i replaced a few relays that the old owner had taken apart, after i put in a new ecu it ran great, i drove it around fine till today it died like it was running out of gas and i could see smoke coming from the passenger side kick panel, the ecu fried again.

my question is has anyone had this intermittent issue or have any ideas what could be shorting out so randomly? and help would be great thanks.

 

I know that when i forgot to hook up the injector ground wire after doing the head gasket on my 22re my check engine light would stay on because everything was grounding through the ECU. Could have done something really nasty to the ECU if i hadn't realized what was going on. Was any work done to the engine recently? Id check all the ground wires really well and report back what you find.

 

Thanks for the reply but no i didn't have a check engine, but i did change out the intake manifold gasket when i changed the valve cover gaskets, but only the upper and i think i remember the grounds all being there, i had even put the jumper in the e1 and te1 and i had no codes.

 

Sounds like you have a chafed wire that is shorting out some place and sending nasty voltage back to the ECU. Time to start inspecting all the wires....

Did any fuses pop when the ECU cooked?

 

check the o2 sensor wires.

 

the only one i found cooked was the defrost in the kick panel which could have already been fried

and i checked the 02 sensor wire looks good from the sensor as far as i can see it, where the it joint the harness because i cant see the rest of it?

 

Also if anyone knows much about the ecu i know what area fried if that helps.

 

Sorry if i wasn't clear with my response, i wasn't saying that you'd have a check engine light, i was just suggesting that you check grounds because things could be grounding THROUGH your ecu. In my case that caused the check engine light to illuminate, despite not throwing any codes.

 

No i understand, and the ground your talking about, it's the one towards the back of the intake, the wire with the disconect in the middle rite? or is there another I'm missing? thanks.

 

This info should help narrow down where to look for the bad wiring. Post it up....can't hurt.

 

the blue guy im pointing at with my knife, looks like a resistor with the resistence just printed on the side instead of the color code, but this is where the smoke left a mark on the lid


here is closer half of it is discolored, like it got to hot and lost its gloss.

 

It would be a better help if you could possibly look at the back of the board and trace where to what pin on which plug of the ecu that reistor goes to. THat would tell us exactly what system is causing the problem.

 

So iv been going threw the ecu and trying to trace it but I'm finding more than one spot that torched so I'm just going to do what i wanted to do in the first place, the 4.3 Chevy swap, I'm selling the motor tranny and tcase if anyone needs it let me know, thanks for all the help guys.

 

Hey i got another quick question, could i just swap my whole engine harness to get rid of that problem and if so does it have to be the 91 exactly? Because i know it only fits the 91 specific ecm but is the plug where it connects to the body different as well? Thanks.