91 300ZX Twin turbo manual trans

So I’ve been having this issue for a while now and it seems to be becoming more frequent. Whenever I am cruising at a fixed speed for very long my car suddenly stops accelerating without me lifting my foot. I can floor the gas pedal when this happens and the engine does not respond at all. Boost gauge climbs to 0 though so I know the throttle bodies are opening. The only solution that works is if I lift my foot completely off the throttle and count to 3, then it behaves as normal, until it decides to cut out again that is. I have cleaned the maf, have a 1 year old fuel filter, 1 year old spark plugs that all look good, I’ve ran fuel system cleaners like redline sl1 and sea foam through my fuel tank and I have no misfires. Only ecu code is 14 because my speed sensor is bad, but I haven’t heard of a bad speed sensor causing anything like this. Oh and also the tps is set at .42v and the idle switch kicks on like it is supposed to. No vacuum leaks. The car runs great in all other conditions, idles healthy, pulls great and it NEVER cuts out when I’m accelerating. Only happens when I hold the car at a fixed speed, and it tends to happen most often if that speed happens to be a slow speed.

Thank you in advance to anyone that helps me solve this problem because I’ve been chasing it for months now and it quite frankly is driving me insane. Also I almost forgot, I checked my o2 sensors as well and both seemed okay. The driver side one blinked kind of slowly and was probably barely within spec of blinking 5 times in 10 seconds, but the passenger one was ripping. Should I try replacing the driver side o2? I also have a spare maf I was gonna use for a dual maf setup later, but for now I may try swapping it and seeing if that helps.

Fix the speed sensor first. I've never heard of a speed sensor doing this either but if you know you have a bad component eliminate it first or you could end up chasing the wild geese.

NolimitZ32 wrote: ↑

Mon Jun 01, 2020 6:39 am

Fix the speed sensor first. I've never heard of a speed sensor doing this either but if you know you have a bad component eliminate it first or you could end up chasing the wild geese.

Will do. Gonna have to wait a week until my next paycheck since I just ordered parts to fix my carrier bearing and tranny mount since mine has started rumbling the car and making noise. The speed sensor has been slightly bad for a long time because the speedometer and odometer weren’t working, but the ecu was still giving me a code 55 until recently

Hey guys, I know it’s been a while but I finally fixed the problem. It turned out to be a bad tps. The one on the car didn’t seem to have any dead spots when I slowly opened the throttle with the multimeter hooked up and it was adjusted correctly. Very odd. The only reason I was able to diagnose it was because a couple weeks ago my car started to randomly idle at 1500 sometimes and would sometimes chill out if I whacked the throttle real quick. Checked the tps and it was still adjusted correctly but I also noticed that whenever I unplugged it the idle dropped back down to like 750. So I ordered a new tps and decided to drive the car with it unplugged while waiting for the new one. Low and behold, the throttle never cut out on me with it unplugged. New sensor installed and adjusted and my idle is normal once again and my car no longer cuts out on me

Hope this helps anyone else that has a similar mystery issue like I did. I have no idea why my old tps seemed fine when tested. I did notice that the new one was much easier to adjust though. My old one would jump like .4v when you barely touched it, making adjusting it a miserable experience. New one adjusted easily in small increments. This was a very frustrating problem to have for over a year seeing as the car would easily cut out 5 times a trip. And my ecu never gave me a tps code :/