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Lowflight · 07-22-2007

From Marc

You're getting tip-in throttle knocks. They are quite common on most LT5's. The issue is addressed by my calibration. This is described on the information sheet that came with the chip. While the knock sensing is tuned to reduce the effect on engine torque, the additional spark advance that is a big feature of the chip work in opposition to that.

The knocks that you are hearing are happening as the throttle opens, initially the engine goes lean as the throttle opens, and it knocks. Beyond about 50% throttle the engine gets fueling for the load and the knocking stops. When I drive a car, I evaluate that situation by monitoring the knock system with a scanner. Normally the scanner reports an approximately 3 degree retard event and then another smaller one. About half of the LT5's do this. The knocks are not harmful because the engine is under light load at less than 50% throttle. Using 93 octane fuel might help. A .050" spark plug gap might help.

We could try to make tuning adjustments for your engine, but some of the improvement in throttle response and low speed torque that you are noticing with my chip will be diminished.

07-22-2007	#10
Lowflight Join Date: Aug 2005 Location: Memphis TN Posts: 201	Re: Problems with Detonation after Plugs From Marc You're getting tip-in throttle knocks. They are quite common on most LT5's. The issue is addressed by my calibration. This is described on the information sheet that came with the chip. While the knock sensing is tuned to reduce the effect on engine torque, the additional spark advance that is a big feature of the chip work in opposition to that. The knocks that you are hearing are happening as the throttle opens, initially the engine goes lean as the throttle opens, and it knocks. Beyond about 50% throttle the engine gets fueling for the load and the knocking stops. When I drive a car, I evaluate that situation by monitoring the knock system with a scanner. Normally the scanner reports an approximately 3 degree retard event and then another smaller one. About half of the LT5's do this. The knocks are not harmful because the engine is under light load at less than 50% throttle. Using 93 octane fuel might help. A .050" spark plug gap might help. We could try to make tuning adjustments for your engine, but some of the improvement in throttle response and low speed torque that you are noticing with my chip will be diminished.