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Old 09-10-2019, 01:47 PM   #5
Ed Wright
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Location: Sand Springs, OK
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Default Re: My son Tony 5.3 Chevy trouble

I work with this stuff every day. The MAF for the 5.3L truck should be the 85mm one piece black plastic unit, with the five pin wiring connector. Often, engine swaps end up with the older 3 piece MAF, which is calibrated a good bit differently.
With a scan tool, you should see 5 to 8 grams per second air flow from the MAF. Depending on idle speed.Normally, at 750/800 RPM, 8 grams per second is normal for a stock 5.3L to 5.7L engine.

Unplug the MAF, it does not run in true Speed Density Mode, it runs in Backup Fuel Mode. Separate tables in the ECU for that mode. If that ECU even has V.E. tables, there is a binary switch that needs reset (Usually $00 to $02) to run in true V.E. Mode.

Many of those late truck ECUs do not even have VE fuel tables. Just a Backup Fuel Table.
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