Installed my JLT intake along with my corsa exhaust about a week ago. I started with the 87 performance tune. Loved it. The car responded very well. This past weekend I went ahead and filled up on 93, and flashed the computer to 93race. At cruising speeds the car feels like its kicking. I do not see the revs or speedo move but I definitly feel it. This does not happen on acceleration. Also since I put the 93race tune on my OBDII / check engine light has come on. Could it be a bad tune, or something else? Any suggestions would be helpful. I am hesitant to take the car in since it has the intake and all.

P.S. the gas cap is not lose

 

this might not be related, but did you make sure your tank was pretty much all finished with the 87 octain? it make take a tank or two (depending on how low you were on fill up) to get rid of all the 87 octain, and be at a more true 93 octain. I'd email/call whoever you got the tune from.

 

whose tunes r u using?

 

When I went back from 93 perf to 87 perf (gas prices are ridiculous down here now and im doing a lot of driving), it took about a tank abefore my car adjusted. I drove the last 93 tank down til I only had about 10 miles left, then put half a tank of 87 in, and the car idled funny for a day. Then drained that and filled it up to 87 and it was working fine.

 

Do tell.

 

that is the first thing that came to my mind too.