Rebuilt ECU, relay still clicks then dies

[krimsonrider]

I just installed a motoguys garage rebuilt ecu. After installing i drove the car around town -lights on, A/C going full ect.- all done after proper temp. was reached. Well the car ran fine with no problems. The next day on the way to work, pucker factor kicked in on the way up a bridge! Car died on the other side though! Symptoms- After driving for a while The MPI relay clicks, sometimes the engine kicks back on, sometimes it doesnt, sometimes i can throw it in neutral and strart back up when rolling. Well its at my shop. What can it be!? Can it be the MPI relay? What items or related items should i troubleshoot? On another note! My auto/trans is stuck in limp mode, but i cant really send that off until i keep the engine from quitting on me. ### help, IM very mechanically inclined, this computerized stuff is still kinda new to me.

 

[steve]

Lets assume that the ECU is good for a second. Any interruptions of the power feed from the battery would cause the MPI relay to click and reboot the ECU. Is your battery bolted down and are the terminals clean and tight. The MPI relay can be bad, as can the ignition switch, or the wiring between these and the ECU.

Steve

 

[krimsonrider]

Thanks for the information! I have a relay I acquired at a yard that I will run and test tomorrow, and I will also check out the ignition switch. I will update this thread after 5pm eastern time. Also, the battery isn't bolted down, but I don't think thats it. Reason being, last friday I tested the car at work and started it up and let it idle for 20 minutes, then drove it for 15 minutes in stop and go conditions allowing the vehicle to only reach 45mph. It didnt die I me. However after placing it back in the shop garage and letting it idle some more It finnally clicked out and died 3 minutes after, but it would crank up avery time and die out shortly after. There have been some occasions when I try to start it up and turn the key I hear a winding sound like the starter is pulling a load but no turns, I leave it alone and it will crank right up, then same cycle.

 

[krimsonrider]

Sorry so long on the update. I replaced my MPI relay and the car runs fine now except for the tranny. Its stuck in Limp mode.

 

[steve]

Thats great news on the relay.

The bad news is that the TCU used the same capacitors known to leak in the ECU and worst the design is such that when they lean and eat through sone of circuit traces they cause a failure that puts 12v onto the 5v power bus and that cooks the other chips. If you get to them before the self-destruct that can be saved but I'm running at about 50% success rate on TCUs that are in limp mode because of capacitor problems.

Steve