stangman53

I recently put on the mac cai and it did not require a reflash check engine light came on it knocks when I hit the peddle and the left and right banks read lean I got yhe superchips tuner it launches like a rocket but does not re-flash can i go to 91 octane to adjust for the knock and will it help

rygenstormlocke

It might help, most tuners want mid to high grade gas. I run 91 oct on mine with no issues. Though I don't have a MAC cai, but give it a shot.

scrming

Seems to happen with the MAC even though they claim it doesn't need a reflash... I think you really need to add more fuel via a tune... we needed to add like 18% more fuel to compensate for my MMR CAI...

stangman53

I am remembering back to the days when I had run a 10 second 69 gto it was always the more air the more gas but when I got a knock it was usually to high high timing or not high enough octane so I am going to try the 91 octane if that does not work do you know if the dealer can do a re-flash or will I have to get an sct xcal tuner.

scrming

What has probably happened is the MAC changed the MAF housing size... this is basically throwing off the air volume calculation... so the computer actually ends up thinking it's gettting LESS air than it really is... since the computer think it is getting less air it , it supplies less gas... BUT in reality you're getting MORE air than stock... so you run lean... causing the knock..

Here's a graph from my car... it's show that the computer thinks my car is flowing LESS air with my MMR CAI than with the stock airbox... which we know isn't true... LOL



hope this makes sense...

stangman53

I see the chart but although i have moved up to the 21st century doesn't a knock usually mean to much air and not enough gas or as it used to be not high enough octane. Again I am going back to carb. engines with no computers the new tech is far beyond my old school knowledge.