stangman53

put the mac cai on the car check engine light came on car knocks when I get on the throttle. tuned it with superchips hi performance would 91 octane hurt the engine

Derf00

If the light came on you may have forgotten to reconnect the Mass airflow sensor (MAF) that sits right behind the air box. If that's fine, check for leaks. If that doesn't resolve anything, put the factory tune back in and see if that fixes it. If it does then the tune isn't right for your car. Does the tune you got require 91 octane? If not, then the going to 91 won't fix anything.

stangman53

I put the maf back on the knocking started before the tune and I read somewhere recently that it needs a re-flash but I thought the higher octane would rid the knock the high performance tune is supposed to be 91-93 for the gt but supossedly 87 for the v6 who knows

Derf00

Well a tune could be anything you want it to be regardless of the engine size. They do make a tune for a V6 that requires 93 octane. What I'm asking is, what is the octane required by the new tune you put in? If it's only 87, then going to 91 may not do anything for the knock and you have a problem somewhere else.

I'd start with the factory tune back in to begin with. If by doing that the knock goes away, put the performance tune back into it and use 91 Octane. That way you've essentially ruled out any other possiblities.

stangman53

The knock was their before I used the tuner

scrming

My guess is your car is starving for fuel... that's why your knocking.. your running to lean... so I don't think 91 Octane will help... you need to tell the computer to add more gas... in the case of my MMR we had to add like 18% fuel to compensate...