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Originally Posted by XfireZ51
BLM is the Block Learn Multtiplier and also known as Long Term Fuel Trim, whereas the the INT is the Short Term Fuel Trim. The INT will change several times before the BLM is updated. When I first started tuning, the old C3 ECM like the 7747 would update a frame every 1 sec. The BLM would hardly move. So I would lock the BLM to 128 and the ECM would use the INT only which updated more frequently. Once the INT would steady out to around 128, I would unlock the BLM and fine tune it from there.
By Injector Dwell, do you mean Injector Bias?
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Thanks for that. That is what I figured.
Well, actually the term is "injector pulse", and the value is in milliseconds.
I had 3 O2s go bad on my '95 LT1; one was bad when I bought it, and like a dummy I filled the wire port on the new sensors with RTV, thinking I'd be protecting it from anything getting in. Live and learn.
Anyway, one O2 sensor would apparently short to ground at about 3000 rpm - reading zero volts. The injector pulse time (dwell was my word...sorry 'bout that) for that side of the engine was more than double the pulse width for the side with the working O2. Lots of black smoke on that side and stumbling, etc. to indicate too rich on that affected side. Once the funky O2 was replaced, the injector pulse width compared almost exactly with the other (good) side.
Unfortunately, I do not see "pulse width" in the 90 version of the ECM software. Too bad, cuz it was very useful, IMO.
But, getting back to the bad O2 sensor question, if the same thing happened in an LT5, I would expect the intergrator readings to be significantly higher on the shorted O2 side, compared to the normal sensor side, yes??
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