92Q's check engine light even after ecu was replaced

[LAQ]

so when i swapped my ecu this morning, the light went off, car seems to run very smooth.then i stopped the car for a while ,started, the annoying 'check engine' light went on again with usual rough idling.

originally the dealer told me it was CAS, i took it to other infiniti shop, told me it was ecu.

i did the self-diagnosis and it was number one fuel injector that wasnt getting the spark from ecu.

i wiggled the maf, made sure it wasnt the problem.

any ideas?

[elwesso]

Coil maybe??? What mileage do you have?

[LAQ]

'bout 118k. coil? havent heard that before, but it is possible.. have you had this symptom on your ride?

[elwesso]

No but if the injector isnt bad, thats the only thing else that can go wrong (unless dennis thinks otherwise)

The ECU sends a message to the coil and the coil fires..... The former wont fail, or if it did thats uber-rare.....

[DAEDALUS]

i did the self-diagnosis and it was number one fuel injector that wasnt getting the spark from ecu.

What self-diagnosis did you do that narrowed down the cylinder? I'm a bit confused by the terms "fuel injector" and "spark." Your #1 fuel injector isn't working? Or your #1 plug isn't firing?

[LAQ]

we did the light bulb check. number one injector wasnt getting the spark to activate the injector. does that make sense?

[DAEDALUS]

Gotcha. I thought you were doing the self-diagnosis of the ECU for error codes. "Spark" is a term associated to the plugs firing, which is probably why Wes mentioned the coil. Disconnect the harnesses on the right side just behind the plenum. Check the injector harness resistance to #1 to see if your EFI sub harness is bad. If it's bad you'll have to replace the sub harness. If it's good you'll have to trace the fault back through the main harness to see where the open circuit is. That wouldn't be fun at all.

[LAQ]

yeah,, im kinda behind in lingo, sorry daedalus.by the way, can you take a look at my ride (daedalus)?

ive almost given up, but i remember how sweet the ride it was on my q when is was purring. i miss that feeling.

help me bring it back,,

[DAEDALUS]

Yeah I miss that feeling too. I wish I had time to work on cars. If I did, my own Q wouldn't have been sitting on blocks since early this year.

[Q451990]

How did the pins look on your ECU harness? Since it cleared up when you replaced the ECU, that would be a good place to start... Has the car had any body damage on the right front that could have caused water entry and corrosion?

Heath

[Q45tech]

A harness short [or lower than 10 ohm injector] will overheat and blow the Darlington transistor in ecu that grounds the injector.

[LAQ]

i looked with magnifying lens, pins look normal.and no body damage on the car..

i hope what q45tech said is not my problem. sounds like a pain to figure that out. what would cause this q45 tech?