PO101 Mass air flow.

Boomer

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Joined
Mar 14, 2007
Messages
309
Points
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Make
Chevy
Model
S-10
Year
2002
Miles
168,000
Engine
4.3
Guys I keep getting this code coming back. The top reported fix seems to be replacing the MAF sensor. The engine seems to run fine so I’m guessing the problem is the sensor. Since my scanner does live data, I figured I’d look at it and upload here so you experts can see if anything looks amiss. I hate throwing parts at things.
 

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grcauto

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I would need to see the trims, load, maf, tps and rpm together for a couple minutes.
You flashed through the trims in a couple seconds but I did see the LTFT were at 13 and 14 which means it's running lean.
 

Boomer

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Understood. I'm not sure what file size can be uploaded here. I was at idle as I"m sure you figured out. 4 days ago, I had PO101, PO131, PO137, and PO151 (low voltage oxygen sensor circuit codes) I cleared the codes and those did not come back on with the exception of 101 today. The truck has been driven daily. My round trip for work is approximately 32 miles. I don't know if that stuff means anything to 101 coming back but, I didn't want to leave out the info. Unfortunately, I can't show all the data simultaneously. As you can see from the screen size.
 

Boomer

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Messages
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PO101 - Have you tried cleaning your MAF sensor?
I have taken it out and cleaned it a couple of times with the cleaner spray you buy at Autozone. I haven't done it recently. I could try it again. I suppose that wouldn't hurt. It didn't look dirty when I did it before.
 

NickD

wrench
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Aug 28, 2007
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Another problem with these things, the PCM requires a start voltage of at least 8.5 volts so that its microcontroller gets a proper POR or power on reset. If not the program counter is not reset to zero randomly reads code that also was not properly reset. Another cause of this lower voltage, starter kicks on, and can get a surge current of close to 800-900 amperes. Problems can be a little corrosion on the battery terminals, grounds, ignition switch that drops an extra volt or two, or a partially sulfated battery.

Common cause of this is no battery caps on a so-called maintenance free battery, hate this marketing term, electrolyte still evaporates leaving the top of the plates bone dry. Bad for consumers, good for battery replacement sales.

Putting a scope with memory across the battery terminals shows if this voltage is dropping below 8.5 volts, won't find this in any shop manual, tell you to use an ohmmeter, good way to fry it.

Getting random codes periodically is a sign of an erratic POR. Most alternators are grounded via their frames and using the cheapest oxidizing aluminum they can find. Another cause of low voltage. Another problem is lack of electroplating connectors, instead of our good EPA helping to solve problems with the waste, banned it in the USA, and if this job is exported say to Mexico or China, really don't do a very good job. EPA never solves problems, just fines you or shuts you down.
 
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