I was going to run some tests to determine for myself, but figured I'd ask here first. In closed loop, part throttle cruise, BLMs cells 6&7 will sink to 109-111 range. All other cells will stay in the 122-128 area. Idle is right at 126-128. Could timing cause this? FYI, that's with stock injectors, stock constant, stock offsets but on a 383 LT1 with a <currently> pcmforless tune.

Let me add that the BLM boundaries are stock, as are the MAF and MAF tables.


Thanks,
RobY
95Z28

 

With low blm's your PCM is reducing the amount of fuel the MAF thinks the engine needs. You could try cleaning your MAF and/or look at your data log where you noted the low blms. On the same rows (same run time), note the grams/sec your MAF is reading. You want to reduce those values slightly in your MAF tables (to tell the PCM that less air is actually flowing thru the MAF at a given hertz, that way it will give it less fuel). It will be trial and error to target a 128 blm.
Hope that helps.

 

With low blm's your PCM is reducing the amount of fuel the MAF thinks the engine needs. You could try cleaning your MAF and/or look at your data log where you noted the low blms. On the same rows (same run time), note the grams/sec your MAF is reading. You want to reduce those values slightly in your MAF tables (to tell the PCM that less air is actually flowing thru the MAF at a given hertz, that way it will give it less fuel). It will be trial and error to target a 128 blm.
Hope that helps.

I've thought about that and I've cleaned the MAF. At this point, I'm not convinced I want to tweak the MAF tables though.

 

I agree, tweaking maf table alot of times just masks a problem. Make sure your injector size is correct. I had the exact same problem or so I thought, I have a 383 with 30 lb svo's, I bumped my injector rating to about 32.5 dont remember exactly but this cleared it right up. Also this was after many data logs, and tweaking of maf table.