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Premium Member
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79 Posts
Discussion Starter #1
Good day

My truck is a 94 NAS with the 3.9L.

Recently, it started running poorly. It surges and hunts for idle at start up, and runs very rich. I checked for any vacuum leaks and found none. I made sure all under hood sensors are seated and plugged in.

The diagnostic box is showing code 12, mass airflow sensor. I followed the instructions on JE Robinsons page to clear and check for other codes, but that procedure did not work for me. Disconnecting the battery momentarily clears the code, but doesn't show any others.

I removed the sensor, cleaned it with MAF cleaner, and it did not change anything. Do these commonly go bad? Anything else I should look at, or should I just find another to swap in?

Thank you
 

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1994 NAS D90
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28 Posts
Good day

My truck is a 94 NAS with the 3.9L.

Recently, it started running poorly. It surges and hunts for idle at start up, and runs very rich. I checked for any vacuum leaks and found none. I made sure all under hood sensors are seated and plugged in.

The diagnostic box is showing code 12, mass airflow sensor. I followed the instructions on JE Robinsons page to clear and check for other codes, but that procedure did not work for me. Disconnecting the battery momentarily clears the code, but doesn't show any others.

I removed the sensor, cleaned it with MAF cleaner, and it did not change anything. Do these commonly go bad? Anything else I should look at, or should I just find another to swap in?

Thank you
I had the same issue last week and did the same exact procedures as you. Currently waiting for my new MAF to get here from o Riley.
I'll let you know how it goes.
One thing I am also replacing is the intake tube that connects the MAF to the plenum. Mine was ever so slightly "chipped" on the intake side. Check that hose/pipe carefully.
 

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Premium Member
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79 Posts
Discussion Starter #3
Just a quick update.

I ordered a Delphi unit from RockAuto.

Installed it and everything seems to be back to normal
 
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