I'm not satisfied with my car's post-cam install power and am suspecting the tune. Although I've got time scheduled for a re-tune (with a different tuner) a week from now, I thought I'd do some forensics to see if my current tune is suspect. I dusted off the old AutoTap scanner and did some logging with it on some deserted country roads, accelerating hard in a few gears and cruising, logging a number of parameters including O2 sensor voltages and ignition timing. What I'm seeing is this:
- oddly, the throttle angle indication reads 19.6% when the throttle is closed. At WOT the indication is 92.9%
- oxygen sensor B1S2 always reads 0mV though I never see an MIL... The B2S2 sensor reads more normally though its indication makes me suspect that the Magnaflow hi-flow cats in my MRT-H are not so good no more.
- during steady state cruise at a couple-thousand RPM, the indicated spark advance is somewhere over 40o. In one log I see 45.5o...
- during periods of WOT, the ignition timing drops down to about 20o and begins to climb as the RPM rises. However, it only climbs to about 23o, maybe 23.5o maximum
- during these WOT runs the front O2s both saturate at 960mV (I also suspect it's running as rich as hell on the current tune...)
I'm most interested to hear what other tuned GTs are running for spark timing under these conditions. With my previous, pre-cam mail order tune, I'd get some tip-in detonation (even with 94-oct Sunoco) if I punched it in 2nd gear at, say, 3500RPM, indicating perhaps slightly too aggressive timing. Now I never hear any such indication. I actually wonder if the values above are closer to factory timing values rather than a properly done tune.
- oddly, the throttle angle indication reads 19.6% when the throttle is closed. At WOT the indication is 92.9%
- oxygen sensor B1S2 always reads 0mV though I never see an MIL... The B2S2 sensor reads more normally though its indication makes me suspect that the Magnaflow hi-flow cats in my MRT-H are not so good no more.
- during steady state cruise at a couple-thousand RPM, the indicated spark advance is somewhere over 40o. In one log I see 45.5o...
- during periods of WOT, the ignition timing drops down to about 20o and begins to climb as the RPM rises. However, it only climbs to about 23o, maybe 23.5o maximum
- during these WOT runs the front O2s both saturate at 960mV (I also suspect it's running as rich as hell on the current tune...)
I'm most interested to hear what other tuned GTs are running for spark timing under these conditions. With my previous, pre-cam mail order tune, I'd get some tip-in detonation (even with 94-oct Sunoco) if I punched it in 2nd gear at, say, 3500RPM, indicating perhaps slightly too aggressive timing. Now I never hear any such indication. I actually wonder if the values above are closer to factory timing values rather than a properly done tune.
