LT1 Based Engine Tech 1993-1997 LT1/LT4 Engine Related

P0100 Code

Old 06-11-2019, 08:20 AM
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P0100 Code

Hey guys,

i have another 97 Trans Am LT1 that is throwing a P0100 code from the MAF. (This is a different car then my other previous post with the P0102 code)

i checked all the wires, yellow is 5 volts, ground works fine when testing with the pink wire showing 12 volts.

all the fuses (engine sensor and #5) are fine.

The second i delete the code and start the car up it throws the code. When I turn on the key to accessory or remove and reinstall the engine sensor fuse I can hear a clicking noise coming from the starter area. The MAF has been replaced by the previous over with a new harness extension. Any ideas? The car does have pacesetter headers and the wires running down to the starter/O2 area is very close to the primaries, but itís weird that Iím still getting 12volts at the pink wire on the MAF.
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Old 06-11-2019, 11:06 AM
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Re: P0100 Code

This code indicates the MAF sensor signal is relatively static, between limits set in the diagnostic. If you have a real time scanner, at idle look for 3 to 4 grams per second air flow. Opening the throttle should show significantly higher flow. If you don't have a scanner, you can use a multi-meter with a frequency counter, on yellow wire. At idle, I think the reading will be in the low 2,000-2,500 Hz range, and should change significantly with opening the throttle. (Computer crashed and still trying to recover files from backup external hard drive).

At this point, it gets complicated and the best bet is to download (free) the factory service manual, courtesy of GaryDoug:

http://www.mediafire.com/?40mfgeoe4ctti

P0100 diagnostic chart starts in Volume 2 of 2, Part 1 of 2, page 6E-498.
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Old 06-11-2019, 12:28 PM
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Re: P0100 Code

Awesome. Sounds like a complicated mess. Would this just be a minor glitch? And can be worked out with some seat time? Or whatís other issue would cause it.
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Old 06-11-2019, 01:09 PM
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Re: P0100 Code

When the code sets, the PCM disregards the MAF sensor, and defaults to speed-density to calculate the mass air flow, based on RPM and the MAP and IAT sensor readings. If the engine is stock or near stock, this works fine. But the more you depart from stock, the less accurate speed-density becomes. Unless the tuner has updated the volumetric efficiency (VE) tables to reflect the engine modifications.

Have you cleared the code to see how fast it comes back? Do you (or a friend) have access to a spare MAF sensor? If so, swap them out and see if the code stays away. That would confirm a faulty MAF sensor.
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Old 06-11-2019, 01:48 PM
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Re: P0100 Code

Originally Posted by Injuneer View Post
When the code sets, the PCM disregards the MAF sensor, and defaults to speed-density to calculate the mass air flow, based on RPM and the MAP and IAT sensor readings. If the engine is stock or near stock, this works fine. But the more you depart from stock, the less accurate speed-density becomes. Unless the tuner has updated the volumetric efficiency (VE) tables to reflect the engine modifications.

Have you cleared the code to see how fast it comes back? Do you (or a friend) have access to a spare MAF sensor? If so, swap them out and see if the code stays away. That would confirm a faulty MAF sensor.
The car is stock so it seems to run fine, in speed density mode.

I have a very cheap scanner, so I will delete the code and within seconds of the car running, itíll pop back on. When I purchased the car, the guy gave me the ďold MAFĒ. I could throw it on and see? I also have one on my other LT1 car. But Iím thinking itís something totally different. I find it weird that Iím hearing that noise down by the starter when I unplug the engine sensor fuse. Unless itís the starter solenoid or something?
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Old 06-11-2019, 03:13 PM
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Re: P0100 Code

Originally Posted by Greg88 View Post

T The MAF has been replaced by the previous over with a new harness extension. Any ideas? The car does have pacesetter headers and the wires running down to the starter/O2 area is very close to the primaries, but itís weird that Iím still getting 12volts at the pink wire on the MAF.
is the MAF extension that is plugged into the stock MAF connector reversed?....and also not reversed plugged in at the MAF?

You might want to buy some tube split loom heat wrap for the wires running near your headers. Not talking about the plastic split loom.
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Old 06-11-2019, 04:04 PM
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Re: P0100 Code

94-97 F-Body LT1's all used the same part # MAF.
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