Leaderboard

I can't help with all of the questions but if you have scanned a GN, it is not too far different. The ECM is one generation newer and more powerful so it has a bit more fine control. The book value for the TPS is .38v-,42v and over 4.0 at full throttle. I forget what the exact level is to get to fuel enrichment, but it is similar to the GN. As far as I know, the IAC doesn't have a desired level, but I could be mistaken. Curb idle with the IAC forced closed is something like 450-500 rpm on the throttle stop screw but it would be super rare for that to be out of whack. The O2 sensor at idle may or may not be active (hot) enough at idle unless it has been driven around so the whole system has retained heat. I have noted idle readings like yours but I don't get concerned about it unless it stays inactive as well as rich fueling while driving. One side note here that may be relevant: when we were resurrecting the red '89 as a family project we noted the O2 sensor had been changed multiple times, indicated in a glovebox notebook. We noted the car did not want to reach closed loop either. After investigating and determining the O2 sensor wiring was good all the way back to the ECM, we finally swapped ECM's. That cured the O2 and closed loop problem, but it will not go closed loop unless driven a bit, idling for extended periods doesn't seem to get what it wants but it will operate fine after it has been driven. The integrator and block learn are the same values as a GN and have the same 128 target value. If yours indicates high at idle, it seems to indicate it is closed loop or they would be locked at 128. Does the O2 start to do something if you increase engine speed, like 1500 rpm for a minute or so? .2 is dead lean accounting for the high fueling adjustment and the changing the O2 would seem in order as a place to start if the age or condition is unknown. I don't know what to tell you about the suffix on the MAF sensors. I have a handful from junkyard runs as well, and I have tested them on my flowbench, and they do seem to indicate small differences in calibration. Not enough to be inoperable but subtle differences nonetheless. From training films I have seen relating to the MAF, it is supposedly a calibrated item along with the housing, a package so to speak. The funny thing about that, is the indicated flow rate in grams per second is a made up number in the ECM, in response to the output frequency of the MAF. I am actually running a 3" MAF from a Chevy 3100, the little brother to the LT1 used as a GN upgrade with a translator. The larger MAF uses the same frequency range as the 3800, up to 10.4kHz, so it plugs right in but of course it is flowing more air at the same reading.