I installed a mspnp on my 97 a week ago. Ran it on a dyno on my stock car and got AFR readings and all looked good with the map that came with the mspnp. After about 3 sessions at Thunder Hill beating the crap out of the car with no problems I came back and heard random popping from the exhaust every 1-2 seconds. I'm stupid and didn't even try logging it before swapping in the stock ecu (didn't want to go home on a trailer), but I did notice the MAP line was slightly pinched in the engine bay. The stock ecu started, idled, and ran perfect after that. This is probably a waste of time to figure out without a log, but what could it be?

- pinched MAP line? I kind of doubt this since the car was running fine with the mspnp outside of the idle problem.
- changes due to higher than usual coolant temps and the tune needs to be adjusted?

 

I get this too with EGO turned on. With it off and idling richer it is perfectly stable. I dont think MSPNP will idle as good as OEM actually (without spending hilarious amounts of time to a rev range you don't want to be in at a track day).

 

I get the same thing. The engine bay heatsoaks, which heatsoaks the IAT, which causes the car to pull fuel and idle lean, which then causes it to misfire. No harm in it, it's just a bit annoying.