91 Twin Turbo bad idle and won't rev past 3,000rpms.

175

Asked by Apr 01, 2012 at 06:09 PM about the Nissan 300ZX

Question type: Maintenance & Repair

So I decided to swap, from my parts car, the 615cc injectors, 300 degree fuel rail, and braided lines to my
current Z. I put everything in correctly, plugged all connectors back into their right connectors on the wiring
harness, and plugged the fuel pump back up. On the first try it cranked up perfectly and idled perfect. I took
it for a drive and she ran perfect, boosted up to 14 psi no problem. I then realized I forgot to put the ecu set
for the 615cc injectors in. So I did that. Took it for a drive and it was idling at about 2,000 and when I would
get above 3000 it would sputter and not go any higher. So I blamed it on the ecu. When I switched them
back, it did the same thing. I've been trying to adjust the idle, but it either goes from 1,500 to 200 in 2
second intervals or stays at 2,000. Either way it won't rev above 3,000 sitting or in gear. The previous owner
deleted the egr, prvr and aiv. Also, the vacuum hose coming out of the fpr going to the, I think it's the carbon
canister, are deleted. With or without the hose coming out of the fpr it still idles like this. The only way I can
get the car to idle decently stable is to unplug the yellow connector from the IACV, and then it still won't rev
above 3,000. I've had and fixed misfires on the car before and this is not a misfire. I will post a link to what it
is doing.

http://www.youtube.com/watch?v=PVNlKFSHKHs

1 Answer

55

its your mas air flow sensor, 90% of the time its just unconnected. if not the sensor is bad. its located under the center nose panel attached to the air filter box. hope this helps

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