Fully OEM. After a 15 minute drive and turning the ignition off I cannot start back up even if I give it throttle (sometimes a cylinder fires if I give it throttle repeatedly but not enough to turn it over). There is a distinct popping sound coming from the exhaust when the car wont start, maybe someone in the forum recognizes the sound. I can start fine when engine is cold.

Video with the noise

Ive tried:
-replacing the battery
-fuel pressure at the regulator when the car wont start, about 40 psi. fuel pump whines when priming, too.
-I'm getting spark when car doesn't start. I pulled a distributor plug and attached an old spark plug, ground to valve cover, plenty of spark when cranking.
-ECT reads 480 ohms when hot, and 3500 when cold. These numbers seemed ok to me. Failing ECT usually causes a rich condition from what I've read, but I get the feeling I'm too lean.

I'm going to start troubleshooting fuel and air more in depth, but I'd like some advice from y'all on how to do that before I get more lost in the sauce. or maybe you've heard this noise before and understand what it means.

 

If you think it's going lean, have you cleaned your injectors? Replaced your fuel filter?

My thought was, have you checked your mechanical timing? And what about your O2 sensor? When cold the ECU runs it in open loop and it just uses the fuel map in the ecu. Once warm it switches to closed loop mode which uses your O2 sensor for fuel trim.

 

Appreciate the reply man. I'll check all the stuff you mentioned and I'll get back to you with some findings, quite busy at the moment though. I hadn't thought about that detail on closed and open loop, how the ecu is going to try and run on sensor parameters if I'm cranking while it's hot basically.

I might have temporarily fixed the issue but I'm not quite sure how yet. I was letting the car idle while the fuel psi guage was hooked up (I wanted to see if my fuel pump was burning out or something the longer the car was on, it works fine) and also tapping my MAP and TPS on my throttle body for some reason. Idk sometimes just tapping around and jiggling wires works. And I haven't had the hot start issue since... not sure if it's because of that or some other random reason I didn't catch. its been a few days without problems so we'll see if the issue comes back. Kind of tricky, I don't like how it's working fine after a good month of this hot no start bs.

 

Another thing that can cause a no start when hot condition is your main relay.