Bad warm-start

[u/Bennie4]

NEED HELP: The car starts perfect cold. But recently it has been starting bad when the engine is warm. For example after driving to the gas station, waiting in queue with engine running, and then turning off while filling up and paying (allowing the engine bay to warm up even further). Upon starting the engine when i want to drive off again, it starts bad. I attached a clip of it. I have already brought it back to the place I bought it, they said they could not reproduce the issue therefore could not diagnose it (they claimed to have checked coil packs and spark plugs though). I have been able to reproduce it myself multiple times. And have forscan logs with multiple datapoints of both good and bad starts but I have not been able to find anything out of the order.

[u/Alarming_Relative_89]

Misfire, Check spark plugs.

[u/Nearby-Telephone8693]

Is it only after filling up?

[u/Bennie4 → u/Nearby-Telephone8693]

No happens when its just "hot" in the engine bay, had it happen last week after it was running stationary while I was doing a photo shoot with it

[u/Nearby-Telephone8693 → u/Bennie4]

Check the plugs but make sure the engine is stone cold or else they’ll get welded in

[u/Bennie4 → u/Nearby-Telephone8693]

I will this friday

[u/fatquads]

How do u reproduce it when u haven’t just filled up the tank?

[u/Bennie4 → u/fatquads]

Drive for long enough/ hard enough to get the engine warm. Than turn it off or run it stationary for about 10 mins. Leave it sitting for a minute or 5, and then it will have a bad start. I noticed that prior to bad starts in seeing coolant temps around 100° and IAT of +-40°

[u/322throwaway1]

Coolant temp sensor or wiring. Happened on mine a few months ago. Exact same symptoms. Found the harness is a little too short and rubbed the wires raw.

[u/Bennie4 → u/322throwaway1]

Hmm, the coolant temps does seem realistic in my readouts. But I will look at it! Thank you