Hi Guys had a weird problem pop up on the VS over the past month or so. My ecotec only seems to pull hard when the ECU has been freshly reset....(e.g fuse out for 2 mins) It has a full exhaust + extractors, mace memcal, CAI, new injectors etc so fairly untouched....but for an ecotec its an absolute freak motor, might not have much top end power but the torque is impressive to say the least. Now normally when I am cruising and I even apply a little pressure to the accelerator it will drop back to second and sometimes first and take off hard....which I like, but of late it only seems to want to do this after the ECU has been reset....if I leave it for a few days then it just seems more slouchy and unwilling to kick down like it normally would (it much prefers to kick down to 3rd instead of second), it seems more hesitant and less willing to rev....yet when I reset the ECU again all is fine. Anyone got any ideas? Thanks
It could just be a faulty ECU or memcal, or it could be something not done properly in the tune on the memcal chip when it was done.. Id try another memcal in that ECU to see what happens, and try another ECU with the "tuned" mace memcal, and also with the normal memcal to see what happens. Ive found that some early VS V6's can do some weird stuff when a later VS memcal is fitted to them. Ive found that the oxygen sensors dont work properly with some later versions of the VS memcal if its fitted to the earlier cars, the long and short term fuel trims stuff up badly too. When you buy and fit a tuned memcal, the guy who did the tune would have used one of the VS memcal factory tunes as a base or starting point for his tune, and most tuners usually use the latest release of memcal for that model as a base for their tune as most of the bugs have been ironed out of the latest releases.The tune I run in my VS is VS version BSTK, which was supposedly replaced by a later tune (factory version BTXP) because of "cold hesitation and pinging problems", none of which Ive ever had problems with. If I try to use a later memcal in it, the 02 sensor readings and fuel trims just go haywire and muck up badly, no one seems to know why this happens. It doesnt seem to effect the later model VS's though.
The ECU is self learning to a point. It will remember the throttle positions for each gear and will change the shift points to your style of driving. If you drive it hard, it will compensate for that and try to keep the revs and shifting in a more "friendly" range for self preservation. Once you do a reset, it reverts back to factory default and will react to your driving with more responsiveness until it starts compensating again.
vs doesn't have torque management or adaptive shifts enabled, so there is no learning. Fueling will self learn from the o2 sensors. Id suggest the problem would be stuffed o2's as it goes bad over time.
