I have a 1990 speed density L98 350 with 24# accel injectors, with the stock ($8D I believe) chip.

At idle, my BLMs will be around 155, I'm in Cell 4, but the car runs smooth, injectors are pulsing at 1.9 - 2 ms. When I start driving, I move to any other cell (typically 6 most of the time) and my BLMs are 108-112. Car runs fairly smooth the whole time.

Why are my BLMs at one end of the spectrum at idle, and at the other end during cruising? I assume that I'm at 108-112 because I have a 22# chip and running 24# injectors.... but what about idling makes the ECM go in the extreme other direction? And how do I fix it?

Other mods to the engine: Airfoil, 8mm plug wires, flowmaster cat-back. Everything else is stock from the factory.

 

I'd suggest looking at the low speed VE table and make some corrections in idle area.

The Accel Injectors might need to have the battery voltage correction dithered a little, if their opening characteristics are much different.