| ...completely eliminated the jerkiness and bucking I was experiencing. After many attempts I have finally found a fix that works for me. I have been examining modifications to the high octane timing map to improve low speed drivability. My goal was to eliminate the excessive off-throttle engine braking caused when timing drops drops suddenly down to a fixed 15’ TDC when the TPS signals On Idle status. The symptoms were low speed bucking, jerkiness under 2000 rpm, and a lack of general smoothness when getting on and off of the accelerator in the lower gears. The problem was eliminated by pulling timing from the low load side and lower rpm edges of the timing map, a smooth off and on throttle transition was achieved. Basically I smoothed the map numbers in these zones, eliminating the large value differences. To be quite honest, the difference is like night and day! This modification should only be considered after all traditional troubleshooting has been conducted to fix driveline problems such as worn differential bushings, and excess driveline backlash, etc. The changes were made using an AshSpec Zemulator. If you do not have an engine management system: could contact AshSpec and ask if they will burn a new EPROM using these parameters. I am running Stage III with upgraded intercoolers and a Selin. Click on the link to see the timing data and which cells were changed. Timing Map Modification to Enhance Low and Mid-Range Drivability
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