TROUBLE!! ECU 85 Nissan Pickup

[babyethan1]

WEIRD!!! found one coil wasnt firing; only the exhaust side.. I started messing with the ECU plugs ( lookn at the ecu from driver side under seat ) the wire harness on the left pulled it out and engine stopped.. Pulled the right plug out engine stayed running, and now both coils are firing !!?? is my ECU bad or can I keep the ECU unplugged ??? PLEEEZze help

[Rev_D21]

This doesn't sound good. First off you really shouldn't be unplugging the ECM while the engine is running, probably some of the worst diagnostics I have heard yet. Have you checked the wire connections at the ign coil itself? Check the connections on the ign coils first. I strongly suggest that you have this truck looked at by a certified mechanic above and beyond that.

[babyethan1]

thnx but no thx REVEREND!!! still cnt pin it.. if connections where bad at coil it wouldnt work with or without the ECM connected!!! Appreciate tho

[PEZi]

go to the 720 forum... i believe its fastboatman who showed his complete new wiring harness.... that is what i am doing as well yet even further simplified as i have a racecar that needs even less wiring that most.... the ECM/ECU is worthless if wired right though!

[babyethan1]

thanks PEZi.. Ill do that, SO!! what your sayn is the ECU/ECM is more then likely wired incorrect to begin with ??

[PEZi]

not necessarily wired incorrect... but over time may have a short etc. somewhere in the system

[babyethan1]

ok ill check on it.. still stumped on Y both coils fire when its unplugged ??!!??

[sacnissan]

babyethan1:

I don't think that you have any evidence of anything wrong. I'm pretty sure that only one should fire under some engine conditions. The ECU may be operating perfectly unless you have confirmed that under the engine conditions of the test, both should be firing.

As posted earlier, it is generally not recommended to plug and unplug ECU (or any computer, no matter how simple) while it is in operation. Re-evaluate your trouble shooting methodology as it has a very good chance of being a trouble creating methodology instead.