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L6 searches at 3000 then falls flat at 4500


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We have a 79 280zx at the shop because the car is misbehaving. Once you get the car up to 3000 rpm, it will fall off like there is no fuel to 2800 ish then pick back up to around 3000 and do it all over again if you hold it there. Once you get past that and go all the way to redline, but at 4500 it just falls flat on its face. We have cleaned the TPS, tried a used working TPS. Cleaned the AFM, new FPR, new o2 sensor, checked for vacuum leaks, checked the timing. We have the color tune and can see a nice blue flame in the combustion chamber from idle to red line except for the 3000 rpm stumble where it goes dark. Cleaned the distributer, new wires, rotor, cap, and plugs. We are running out of ideas. and thoughts?

 

Jimbo

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Unplug the computer a bunch of times

 

REALLY?

 

Exactly what is that gonna do?

 

 

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Try playing with the AFM arm at the stumble and see if opening it up or closing it more helps. I would suspect there is a worn spot on the carbon trace in the AFM that is causing both issues. Kind of like when you get an old TPS sensor and there is a dead spot from like cruising and constantly modulating throttle pedal focused on one small particular spot.

Id say its time to follow the FSM AFM test procedures.

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REALLY?

 

Exactly what is that gonna do?

 

 

----------------------------------------------------------------------

 

Try playing with the AFM arm at the stumble and see if opening it up or closing it more helps. I would suspect there is a worn spot on the carbon trace in the AFM that is causing both issues. Kind of like when you get an old TPS sensor and there is a dead spot from like cruising and constantly modulating throttle pedal focused on one small particular spot.

Id say its time to follow the FSM AFM test procedures.

Its going to rub any corosion Off of the 20+ pins that go to the ecu on this 30+ year old computer. Worked for me and lots of other people. Thats what

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