Lean cruise vs. poly engine & gearbox bushings

[Mud_]

Not sure this warrants its own thread, but I wanted to capture the information somewhere. I've found that my poly-bushed drivetrain has made me more in touch with what the car is doing - no surprise there. I was getting a not catastrophic but noticeable low frequency shudder in low-throttle 3rd/4th gear that had me thinking prop shaft unbalance or maybe even gearbox problems. Sussed it this morning - lean cruise! Obviously the engine isn't very happy with my combination of bits and the factory lean cruise settings. It would be interesting to know how the standard engine deals with the abuse of lean cruise, i.e. whether it just shrugs it off or similarly shunts (and is masked by standard isolation). Mostly I love the poly mounts - just a warning for those considering going there - long term the shunting may be damaging for all I know.

Also apropos of nothing much, I'm driving around in full open loop using alpha-n tuning to get the TPS VE table right and generally feel out alpha-n on EFI live COS5 (thinking about those ITBs...). Strip out the MAF and the car feels more responsive...getting more subtle, but also true of the o2s...then another small improvement with no MAP-referenced VE. Obviously you're losing something each time, but it's interesting how the sensors can make the engine feel more coarse/laggy compared to a (very accurate) OL tune. I'll add some sensors back in if I can - I'm not really advocating a full OL tune, although with a little effort logging and tweaking throughout the year it seems viable...especially since it seems to snap between cold and hot in the UK with little middle ground!