Not The Ecu, What Next?!!?

[Guest jjohart]

Hi, I just got a 83 80ZXT ECU from autoecu.com, and plugged it in, but my car is doing the same things: 1. Stalls, bucks/surges, misfires, knocks at any engine speed under 2-2,500...so that I am driving in the snow with the engine revving, and my hand on the handbrake to keep revs up when coming to a stop in traffic, and being featherlight (to the point of wearing down the clutch) on takeoffs in this snowy Boston Thursday!!

My mechanic will take it back in next week, and do diagnostics. From his previous tests, the fuel injectors/fuel pressures are ok, plugs/wires connections are clean, and he suspects the AFM, so I'm ordering one up which I have JUST ENOUGH mechanical ability to swap and see if its that before hand.

So, IF IT ISN'T the AFM now, can anyone give me anything else that could cause such a DR.Jeckyl/Mr. Hyde driveability issue--the car seems fine under boost at any speed, and the misfiring sound/stalling goes away as long as the car is kept at speed (i.e 40+/2,000+rpms)?

THANKS a lot from this mechanically inept potential late model future Honda owner!

[Clifton]

I would get another mechanic. If he suspecs the AFM he should check it. The specs are listed. Maybe someone else with stock EFI knowledge can help though.

 

I just read your other post. Your ECU is not OBD I or II.

 

My .02... I Would put a timing light on it and rev it to see if it stays were it should or moves all over. A dial advance light would be better so you can check as it adds timing. Either way you will see if it's steady, increases with rpms or is all over. If it's knocking at 2K it's just over advanced, not detonation, especially if there really isn't any load, and no boost, I would guess more than 40*.

[Guest jjohart]

Thanks Clif

I'll forward your reply to the mechanic, though I don't know what he's going to think about the suggestion to get another one (around here, that's easier said than done!).

Meanwhile, would a timing issue also produce the car dying/gasping/sputtering and stalling out...it seems that once the car is warm, if I let the revs idle at less than 1,500, or go off the gas pedal, the idle eventual starts sputtering and sounding rhythmically like a misfire, sound chaning to "bu-Bu-bu-BU-bu-bu-BU-BU-bu-bu-bu-BU"(more chainsawy like metallic! as well) and then worsening as the idle drops near to stall (1,000 to 2,000rpm), sounding like BU-BU-silence 1/4sec-bu-BU-silence-uh-buhh-bu-BU!!!!

Sorry, just trying out the PBS Car Talk 1 1800 show segment, but that is what it sounds like!

Thanks

JOhn

[Clifton]

I only sugest a timing issue as you said it was knocking. It may be something else. Another possible cause could be severly worn distributor bushings. That would also cause the problems you describe. You could check that yourself. Just pull the cap and wiggle the shaft. It will have a slight amount of play, about 1/32" - 1/16" roughly. If it moves alot that's a problem.