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Hey everyone, I’ve got an 87 NA z31 5 speed and I’m experiencing a hesitation while accelerating around 2500-3500 RPM, like from a stoplight. Here’s what I’ve done- replaced fuel pump and fuel filter (because they were faulty, car was abandoned for 11 years.) TPS works and is adjusted correctly, air filter is new, throttle body is clean, does not appear to have any vacuum leaks. Fuel pressure regulator appears good. New spark plugs, wires, rotor, coil, new CHTS and crank angle sensor. New PCV valve. Things I know- fuel temp sensor appears to be giving slightly wrong readings, have not tested O2 sensor. Car will almost always start great and idle perfectly however after being warmed up idle will be about 1100 RPM. This has only happened a few of times over the past year but sometimes when I start it in the morning idle will instantly go way down and will die if I don’t give it any gas. Once I give it gas (like 1500 RPMS) it will idle normal, again this has only happened a few times but perhaps it is a sign of a bad sensor or whatever that could be causing hesitation. Car idles very smooth and does not misfire otherwise. Important- I have checked for ECU codes, there are none, and this is after like 500 miles of driving. Does anyone have any idea what the issue could be? Thanks
 

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Hey everyone, I’ve got an 87 NA z31 5 speed and I’m experiencing a hesitation while accelerating around 2500-3500 RPM, like from a stoplight. Here’s what I’ve done- replaced fuel pump and fuel filter (because they were faulty, car was abandoned for 11 years.) TPS works and is adjusted correctly, air filter is new, throttle body is clean, does not appear to have any vacuum leaks. Fuel pressure regulator appears good. New spark plugs, wires, rotor, coil, new CHTS and crank angle sensor. New PCV valve. Things I know- fuel temp sensor appears to be giving slightly wrong readings, have not tested O2 sensor. Car will almost always start great and idle perfectly however after being warmed up idle will be about 1100 RPM. This has only happened a few of times over the past year but sometimes when I start it in the morning idle will instantly go way down and will die if I don’t give it any gas. Once I give it gas (like 1500 RPMS) it will idle normal, again this has only happened a few times but perhaps it is a sign of a bad sensor or whatever that could be causing hesitation. Car idles very smooth and does not misfire otherwise. Important- I have checked for ECU codes, there are none, and this is after like 500 miles of driving. Does anyone have any idea what the issue could be? Thanks
I've no idea about the electronics involved but I can say that it seems as if the accelerator cable or connections needs adjustment or tightening up, plus the idling speed needs to be adjust (we have a 1972 240z and almost every adjustment is manual), Good luck!
 
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