[PieGuy]

I wouldnt say its common...I have many 'highly stressed' (its a road car, it shouldn't be that stressed) turbo cars that will not misfire under heavy load, not enough to trigger the CEL thats for sure.

Where are you located whats the highest Octane fuel you have access to?

 

[PieGuy]

I just believe the Mclaren check engine light is far too sensitive. There have been many incidents reported on here of it going on and then off after the car has been turned off awhile.

I’m in California ,so 91 is all the pump octane I get. I add torco to raise the octane .

Interesting, can't say I have any experience with using 91 while on track...have you tried using higher octane at track only, 93+ if you can get it for 'off road' use?

 

[PieGuy]

I would be careful with any additive. You are better off buying higher octane at the track and letting the ECU adjust for the increased octane. The Torco may be the source of your CEL.

@Gary(SF) Its unleaded, primarily its octane booster (its main ingredient is rated at 100 Octane)

I know Torco makes race fuels etc, I assumed you were using an additive not their 'concentrated' race fuel Its a mix of really decent octane boosters, nothing wrong with it..in another life i used to pour toluene in my tank...a bit more potent than Torcos race fuel concentrate haha.

Didnt realise your car was tuned, could be an issue there too.

Kind of diverged from tire pressures..