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5.3 maf trouble

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Old Aug 19, 2008 | 08:57 AM
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Default 5.3 maf trouble

My transplant is running but there is one snag. If the MAF sensor is connected it idles rough and won't run very well. Disconnect it and it smooths out and runs OK. We used the factory harness. The guy who programed the ECM suggested I check the wiring on the CAM Position Sensor, Crank Position Sensor and MAF Sensor. I did this and everything is clean. Actually I haven't checked the Crank Position sensor because I have to take the starter off to get to it. He also suggested checking the power and grounds to the 02 and MAF sensors. I'm not sure what voltages to look for there.

I'm stumped. If it's not a bad wire what else could it be? Is anything routed to the instrument cluster then back to the ecm? If so we aren't using the cluster.

Here are the basics on my transplant;
2004 Chevy Silverado 5.3 with 4l60e
Used factory harness but no instrument cluster.
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Old Aug 19, 2008 | 11:38 AM
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Is it throwing any codes? When the MAF is unplugged, it throws the computer into Speed Density mode. Has your tuner adjusted the MAF tables for the particular MAF that you are using?

Jack
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Old Aug 19, 2008 | 01:25 PM
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It wasn't throwing any codes when the MAF was connected. The MAF is the original so I'm assuming it shouldn't need adjusting. What is speed density mode?
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Old Aug 19, 2008 | 05:11 PM
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Does the engine produce water in the exhaust, and does it smell gasoline?
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Old Aug 19, 2008 | 06:19 PM
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No unusual smells or water in the exhaust. It runs good as long as you don't give it too much gas. I drove it from Birmingham to Nashville and got 18 mpg. Can't wait to see what it gets when I get the MAF working.
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