LT1-LT4 Modifications 1993-97 Gen II Small Block V8

High BLM's in Fuel Trim Cells

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Old Aug 7, 2009 | 07:19 PM
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Default High BLM's in Fuel Trim Cells

Just finished putting the new 396 LT1 in the car. I have been driving it around the past few days and doing some data logging with datamaster. It looks like my BLM are extremely high in every fuel trim cell except for 10 and 11. I have both datamaster logs and my bin file. Anyone willing to take a crack at why my BLMS are so high? PM me with your email and i can sent the files.

Thanks,
Jeff
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Old Aug 7, 2009 | 08:24 PM
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Originally Posted by Formula934
Just finished putting the new 396 LT1 in the car. I have been driving it around the past few days and doing some data logging with datamaster. It looks like my BLM are extremely high in every fuel trim cell except for 10 and 11. I have both datamaster logs and my bin file. Anyone willing to take a crack at why my BLMS are so high? PM me with your email and i can sent the files.

Thanks,
Jeff
Where are they? 128 is "dead on" If they are high that means the ecm is adding fuel to reach its "target" whatever the "target" is set at.

High BLM is usually an indication of an exhaust leak or a vacuum leak behind the MAF at idle or cell 16( I think) Or just lean.


What does integrator say? This is the short term adjustment to fuel.


I would be careful running the car HARD until you figure this out.
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Old Aug 7, 2009 | 09:13 PM
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In cell 16, at idle, LT counts are 134,145. ST counts are 132,127. Watching cell 16 at idle the ST moved down into the 120 range on both L and R but they are still split ( 127, 123). Long term BLMS stay high and split (134,140). Cell 18 is also extremely high. LT BLMS are 138,141 and ST BLMS are 123,118.
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