| This post updates earlier posts wherein I discussed the modification of Timing Maps in an effort to improve the smoothness of on/off throttle transition characteristics. When accelerating or decelerating at low speeds and/or light load conditions, such as parking lots or cruising under 30 mph, the engine and drivetrain experienced abnormal bucking and jerking. It was not a smooth, modulated, transition up and down through the rpm bands as load increased and decreased. It was theorized that the problem was caused by the extreme difference in timing values in adjacent cells of the ECU map matrix. Note in the upper left corner of the OEM map how the timing values jump from 15' BTDC immediately up 38-40' BTDC. These are values set as the engine transitions back and forth from its idle conditon. The 15' BTDC being set by the ECU whenever the TPS-controlled 'On Idle Status' is realized. Likewise, when coming down off throttle there was a sudden 'engine brake' as timing sharply drops back from a cruising 30-40' BTDC to the On Idle Status of 15' BTDC. In my opinion, it is this sudden transition, in such a short period of time, which causes the engine driveline bucking behavior. The fix was to reduce some of the low load / low speed timing values in order to establish a smoother transition in timing. The chart below illustrates the old OEM map on the left; he New Version Map center, and those matrix cells the timing was changed and by how much are identified on the right. 
It should be noted that this latest version is a drive-tested compromise between maintaing enough timing to preserve good low speed power and mileage; while also providing a smoother driving experience. As others have noted, one could excessively lower timing values across the upper left hand corner of this map to achieve good low speed driving characteristics. However that smoothness would come at the expense of lowering engine power, and poor mileage while cruising in a high gear and low rpm. After fifteen (15) versions of this map, and approximately ten (10) hours of in-car testing, I think these values are the best compromise for my engine car setup. I am still fine tuning the zones around 1600-2000 rpm and in TTP column 8, and may add a few degrees back. Those two points were very sensitive to too much timing would quickly create a surge when powering on, and excessive braking when powering off. I thing every engine is going to be a little different here. Finally, the low speed driving characteristics which prompted this mod are NOT A PROBLEM in all Z32s. It is a common issue, but certainly NOT prevalent. So if your car has a smooth on-off throttle behavior; then I'd leave well enough alone. However, if you have a problem similar to mine, and like myself have exhausted all the mechanical remedies, e.g, driveline slop, worn bushings, etc.; then maybe the timing maps are something you might want to look at.
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Timing Map Modifications to Enhance Low Speed Drivability - 
