First time out with Scanmaster

[bishir]

I posted this in the Scan tool tech forum and I think it was in the wrong place....



First my car's vitals: 87 GN mostly stock, 93 Red Armstrong chip, 93 Gas, 2.5" stainless exhaust w/ 3" cats, adjustable wastegate set at 17lbs boost.

The scanmaster instructions said 3 degrees of knock is acceptable for pump gas. Fortunately my car stays at around 2.8 most of the time when near 17lbs of boost. The fuel readings were great for a stock fuel pump and injectors at around 800-820 most of the time.

However, there are a few issues I'm having. When I let off the gas quickly after boost the knock jumps sometimes. Most of the time it jumps to 3.8-4.2, but once it jumped to 9.1 when I let off the gas quickly. I'm thinking this is normal since the car is quickly running lean for a second once I let off the gas. Is this true?

Another thing, is 3.8 too high or is on the borderline? I'm really happy with the performance so I'd hate to get too worried. I'm not looking for major modifications, but what could I do to bring down that knock number without decreasing boost. I'm sure there are many things, but I would like to start with the very simple and non invasive.

I've also noticed that the knock is easier to control if I manually shift. If I take off from a roll or start when in drive or overdrive that's when the knock readings go above normal. Do you have an idea as to why this is happening too?

Thanks for any responses,

James

 

[Red Regal T]

The way I look at it is, the knock reading I'm concerned about is what I get from a dead stop to WOT through all the gears. WOT is where you want little or no knock retard. Sometimes you'll get knock at shift points or when downshifting, or giving more throttle. These are not important unless idicating some problem. WOT knock is.

 

[bose]

knock

Run better gas or mix a 30% mixture of xylene.Bruce

 

[mike85gn]

The ideal amount of knock is exactly 0. Any more and you'll start loosing power. If you get knock on shifts then it might be false knock, there are chips that have false knock ignore at the shift points. Try turning your wastegate rod up 1/2 turn to lower the boost just a tad. That might be the ticket. Set your boost lower then tune your fuel. Then gradually increase your boost until you see KR, then back it off a touch. Good, reliable performance.