Hi People, I have an NC race car with a 2.5 conversion fitted with a GT2860R turbo running on E85 with a Megasquirt3 by MS Labs stand alone ECU. Goes great but after a few laps at full noise, the engine check light comes on solid unless I back off then it goes off, turn up the wick again and it comes on solid. Dmitri at MS Labs suggested disconnecting the positive battery cable to reset and it does but the problem comes back after 4-5 laps. Obviously no OBDII... Someone suggested AFR ratio is incorrect, someone suggested the O2 sensor is stuffed, someone suggested intake air too hot... Temperature gauge reads normal...Any suggestions as to what is causing this? Cheers, Barney

 

On the NC, the CEL comes on in two cases, engine overheating or knocking. In both cases, it starts flashing first, and if for example the overheating continues, it will flash faster then turn on solid, until the coolant temp drops below the tripping point. It will NOT turn off if you simply back off. If the source of the problem is knocking, it WILL turn if you back off the throttle as the knocking obviously stops. Knocking however does not cause the CEL to switch on "permanently", it will always just flash rapidly. Can we confirm that when you get a CEL, it is on and steady and not flashing?

 

On and steady,....seems like it may be overheating....

 

If it is overheating, it would go through stages 1 and 2 first (slow blinking, then fast blinking, then solid on). Also, it doesn't stop if you simply back off the throttle. The temp needs to come down, and that doesn't happen in 1-2 seconds. The default config is 105C -> Slow blinking, 110C -> fast blinking, 115 -> Steady on. So I don't see how you can instantly go from 104 (no CEL) to 115+ (steady on) with no steps in between, and back. Maybe post a log?