Still trying to get the LT1 running right since the engine swap. Put a stock 95 F-body LT1 into an 86 T/A with a 700r4. !VATS, !AIR, !CCP, !EGR. Been fixing it but still finding new problems. So far I have had a bad MAP and bad O2's but have replaced them. Fuel pressure is good but slightly high. 39 PSI at idle, 47 psi at simulated full throttle. Compression is good. Madz28 tuned.

Anyway, with MAF plugged in, I'm seeing 112/115 blms at cell 16 at idle after letting it idle for a while. All other cells while driving are low blms.

I dont know if it would do any good to unplug the MAF but i figured i'd try it. BLMS hit 135/138 with MAF unplugged in Cell 16 at idle after a while.I reset the battery each time before I changed the MAF conditions. I have spark retard in every condition when i stomp on the accelerator quickly at idle say to at least 3500 rpm. No noticable pinging/detonation, the replacement MAP got rid of that. I am seeing a spark reatard almost always with light crusing and any acceleration.

Shouldn't the BLMS be the same with the MAF as without the MAF if everything is operating correctly?

 

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No, the BLM's will not necessarily be the same with and without the MAF.

MAF measures mass air flow, and the PCM adds the required fuel. If the MAF isn't accurate, or the MAT calibration table isn't correct, the PCM has to adjust the BLM's to get the fuel right.

When you disconnect the MAF, the PCM calculates the mass air flow from engine rpm, the VE tables, the IAT and the MAP readings. Then the PCM adds the required fuel. Any errors in the VE tables, IAT or MAP readings will cause an error. If there are any significant mods to the engine, the VE tables could be off. The BLM"s will adjust accordingly.

Hence, no guarantees that BLM's will be the same with and without the MAF.

 

Thanks Injuneer