NEED HELP..fine when cold, missing when hot

Buffhulk

This has been going on for 2 weeks now. I went to fill up on e85 and on the drive there my 370z single turbo was fine. On the way home it started missing. I sent a log to my tuner because there isn’t a check engine light and he said something is happening on cylinder 1 either a bad injector or coil. So yesterday I change the coil and starts up fine and runs good (because it’s cold) then once I let it sit a bit and get warm it’s comes back. Does this sound like the symptom of a bad injector? I don’t have any check engine light at all so diagnosing this is becoming challenging and tbh I do not want to remove the intake manifold on a guess cause that takes for ever. Any help would be great, thanks in advance.

gbrettin

Odd that it started after a fill. Maybe the fuel had some water in it. E85 likes to try sucking in surrounding moisture.

Buffhulk

E85 content is at 79… would it be normal for it run fine while cold then when hot missing?

THE BULL

It's possible the injector is not atomizing as it should.

During cold starts the engine runs pig rich and ecm adjusts timing accordingly to provide a fast warm up however upon operating temp injector duty cycle is dialed back for smoother idling as the timing goes down to 10 degrees.

An injector that's not atomizing properly will dump droplets instead of fine mist causing a misfire.

This happening on cyl one can confirm the theory a bit since its the first cyl that receives fuel. Whatever contaminants passed the filter hit the first cyl and possibly changed the spray pattern.

You should look into having them cleaned and flowed first before you keep going down the diagnostic road.

Spooler

Pull all of your injectors and have them tested. Pump E85 without proper filtration can kill them quick. If you stick an injector say goodbye to the engine.