L03 1992 RS.
92Blue's car, suddenly its getting 6 MPG, and the Winaldl shows 150 BLMS at idle.

the car seems to RUN fine, however, but feels little low on power for an L03 even, it has 3.73 gears, and a T-56.

while driving the BLMS come back to 128-130, but work their way to 150. the O2 IS reading very LEAN, but the exhaust almost smells rich....

all the sensors appear to be functioning.

the TIMING appears to be bouncing a little much though, although the idle is stable. And it only looks like hes getting 10* total advance. When the Ignition wire is unplugged the timing is 6*, but while plugged in it looks like 15* base timing, with 25* total timing. I checked in neutral. no knock counts.

 

I'd say dead O2 right off the bat, no diagnosis. O2s seem to fail most often by reading lean (low voltage) causing the ECM to keep going fatter and fatter to compensate. A massive exhaust leak near the O2 doesn't do much to help it's accuracy either.

..........Or the injectors are not flowing what the chip is expecting them to flow (either too small or fuel pressure is way low).

A TPI example, knowing this is not EXCACTLY your situation with the TBI motor in question:

This is exactly how my brother's 87 GTA acted when the chip was burned for 30# injectors but the ones in the motor were actually 24# (unknown to us until we really got down to the nitty-gritty and discovered the problem).

BLMs reset on every key-off restart, at least as far as my expereince goes with scan tools shows on EVERY 3rd gen Camaro and other GM products of similar vintage. You would think BLMs would carry over from start-to-start but my expereince is that they do NOT. Beleive me, I really wanted them to act that way but they don't. You start at 128 in every block every time you do a key-off restart. That's the long way around the barn to say that it's totally normal to start at 128 in every cell and slowly work up to 150 or wherever it normally stabilizes over maybe 20 minutes of drive time under various throttle/load conditions. Use the BLMs you eventually stabilize at as your ultimate guide.

BTW- on a TPI the maximum BLM value is 160. That's as far as the ECM is willing to go. On a TBI maybe they set it a little tighter (150). Don't know. Just be aware they won't roll on up to 255. The factory sets a limit to how high it'll let things go. And no, you won't instantly throw a code when you hit the top stop. You could drive our car for HOURS pegged at the 160 BLM top stop before it would throw a lean O2 code in our 87 TA.

None of this answers your direct question but I hope it helps steer you in the right direction with diagnosis.

 

well damon he will def. replace the o2 sensor, and possibly replace the injectors as well.

the thing thats concerning me is the timing. doesnt it seem odd hes getting about 29* total advance? and if the light is correct, hes got about 20* of initial timing...

that means the ECM is only adding 9* of total timing... under high vacuum low load conditions... (neutral 3000~rpms)

i know from experience cars like more than 29* of timing, especially on the highway.