My car has recently started to "pop" from the exhaust maybe 3-4 times when it is started when warm, does not matter if you simply run the car to temp and turn the car off and back on again it misfires every time.

What do i need to look at to rule out in order to get to the bottom of it?

My car is HKS supercharged with ngk 1 step colder plugs, have done maybe 5k miles on the plugs, Hondata 4 bar map sensor - aem V2 ecu, which is locked and i cannot access it as its been pass worded, no lights on the dash, and the car seems to run fine after the missfires on the warm start?

cars been mapped for around a year and never had this issue up until now

i have the car booked in for a remap so i can get rid of the password but would like to sort of any problem the car might have before hand as i obviously dont want to waste money mapping a broken car to have to pay again at a later date.

What are the usual suspects to cause this? would a faulty head gasket let coolant through this quick? my car seems to use no coolant and does not smoke but has had a issue with over heating (atleast on the dash) since going supercharged the temp gauge climbs after a full pulls which is another reason for the remap.

Could it be a sign of a bad engine coolant sensor?

 

Maybe injector dribbling when it's off slightly? Pull the rail and check (I think S2000s have injector clips so the injectors will stay in the rail with pressure, if they don't, don't pressurize it with the rail unmounted!).

A leaky HG when warm will cause the engine to cough and sputter a bit before clearing up, never a backfire in my experience. And yes, I had a crappy 4Runner with a slightly leaky 1GR so I got to enjoy that sputter for a while.

 

Pops in the exhaust, barring much larger problems, have in my experience been coil packs.