Hello all, first post because I haven’t found another thread with the same exact issue.
Anyway I’ve been rebuilding this 1997 GST spyder that’s came with lots of challenges.
Engine has been rebuilt, cam,crank,ect sensors, power transistor,plugs,wires, fuel pump, fuel filter, battery, fuel pump and mfi relay, even another ecu have all been changed. Had the car running and driving a few weeks ago but started having a problem due to my crankshaft sensor getting destroyed by the crankshaft plate loosening up due to a crankshaft bolt issue which has been corrected. I replaced the crankshaft sensor with a used oem sensor that has the car starting up effortlessly. Car warms up no issues at all idle is perfect, after about 5 minutes time, it begins to miss and shortly after will shut off and WILL NOT start until engine has “cooled off”. I thought this was temperature related somehow around 150 degrees coolant temp it would have issues. Took the thermostat out to test, still having the same problem at the same time mark. Could my used oem crankshaft sensor be causing this problem? Only thing that isn’t new at this point. Battery reads 13-14v constantly while motor is running. Where do I go from here? thanks

That battery voltage is good. I would try a new crank sensor and cam sensor, or at a minimum, one that you know 100% work properly. Maybe also try to plug the ECT hole, and maybe run the engine with the ECT hooked up, but in a bottle of cold water, or something of that nature to override that sensor, and trick the ECU to thinking the engine is still cold. Just a thought.

The 5 minute issue sounds like a MAF problem. Try unplugging your MAF, start the car cold, let the car idle and see if it dies after it warms up. If it keeps running, your ecu is gathering bad data. With the MAF unplugged, it is ignoring the data from several sensors. You may have to test several sensors to see which one is the culprit.

Thanks for the replies,

Turns out that oem crank sensor I had in there was the culprit. Swapped it out and now were running. Weird that would be possible but nothing surprises me anymore with these cars

Glad you got it figured out and fixed. Thank you for following up with your solution, so others can be helped in the future.

The lesson here is that engine control sensors are almost always better new, than an unknown condition of used.

TylerGST said:

Thanks for the replies,

Turns out that oem crank sensor I had in there was the culprit. Swapped it out and now were running. Weird that would be possible but nothing surprises me anymore with these cars

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Just as a follow-up to your follow-up, but what was the issue with the crank sensor? What made it bad? Physically broken, damaged wires, something else? Was there ever any clicking noises from that area?

spyderdrifter said:

Just as a follow-up to your follow-up, but what was the issue with the crank sensor? What made it bad? Physically broken, damaged wires, something else? Was there ever any clicking noises from that area?

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Nothing visually wrong, wires all good etc. looked like a perfectly good used oem sensor. Did have an episode after my original post where there was a lot of clicking happening fuel pump was priming fuel pump relays clicking etc. just started happening with the key in the on position after a while. At that point pretty much knew it was that sensor. Did the old back probe the connector and crank voltage test and numbers were out of range. But still would start up instantly every time haha