Can someone explain what BLM's are?
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Joined: Mar 2003
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From: Severn, MD.
Car: '88 T/A and '90 T/A
Engine: LB9/383
Transmission: T5/700R4
Can someone explain what BLM's are?
Can someone please explain to me what BLM's are? I'm new to the ECM diagnostics and tuning and have been messing with a buddy's auto xray this weekend.
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Joined: Mar 2003
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From: under the hood
Car: 92 Z28 heritage
Engine: 5.0 TPI
Transmission: T-5
BLM stands for block learn memory. It has to do with short and long term fuel trims. Short term fuel trim is what the computer has to do with the fuel (lean it out, enrichen it) at this very instant to keep it a 14.7:1. The long term fuel trim reflects what the short term trim has done over time. This is what block learn is. I believe it is on a scale of 0-255, with 128 being the neutral point. The farther from 128 the BLM is, the more that computer has had to change the short term fuel trim to keep things happy. I can't remember if 127 and below is a rich block learn or if 129 and up is, but this is what it is. My numbers might be off slightly also, and I'm sorry if they are.
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May 17, 2020 10:44 AM