The pesky P0101 - Chevy and GMC Duramax Diesel Forum
01-04.5 LB7 Duramax Powertrain Discussion of components that are directly involved in the power production and all that is needed to get and keep the truck moving . Engine , Transmission, Etc.

 
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post #1 of 7 (permalink) Old 03-21-2015, 03:03 PM Thread Starter
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Location: Yuba City, CA
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The pesky P0101

I've had the P0101 code for quite a while, saying "Mass or Volume Air Flow Circuit Range Performance." I am stumped and unable to figure it out. I've done a bunch of reading on the issue and would really appreciate some input.

Things done so far:

- Had a mechanic go over wiring to make sure it was all ok. (He also hooked it up to his scanner and told me that when under load the ECM commands a negative value of air intermittently. Not sure what that could mean)
- Used a known good MAF sensor.
- Replaced ECM
- Pressure tested all the turbo lines. (Had a couple leaks, but fixed now)

I now have the EGR valve and cooler off, but to be honest, I don't really know what I'm looking at. I know that it potentially could be the issue, but don't know how to tell. The valve does move when a vacuum is applied. I also don't know if it could possibly be one of the other sensors. Anyone will some knowledge and input on the issue would be greatly appreciated. Also, I'm in California and need to get it smogged, but am unable to until i get this code taken care of.

2002 Chevy Silverado 2500HD
280,000 miles
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post #2 of 7 (permalink) Old 03-21-2015, 05:28 PM
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P0101 is set by any of the following,

-EGR Control Pressure Sensor
-Mass Air Flow Sensor
-Mass Air Flow (MAF) Sensor Performance

The acceptable range of the MAF is,
1.014v to 4.670 v
11 kg/hr to 1620 kg/hr


Reasons for the DTC,


-Detects an in range sensor fault.
-It can also detect an open circuit.
post #3 of 7 (permalink) Old 05-05-2015, 12:37 PM Thread Starter
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Well I finally got my hands on a decent reader (Edge insight) and found that I'm not getting enough air at wot. I'm leaning towards it being a worn out turbo or injectors maybe causing the P0101, but would like to get another opinion. Below are the numbers I'm getting.

Balance rates:
1:+2.8 2:+2.7 3:-2.6 4:+2.2
5:+3.3 6:-2.5 7:-4.1 8:-0.1

MAF:
When off: 3.4g/s (should that be 0?)
At idle: 44g/s cold and 40.3g/s hot (should be 42-50 g/s)
WOT: Most I got out of it under load was 346g/2 (should be 420g/s WOT at 2-3 shift)

Fuel Rail Pressure:
Cold. Desired: 5.7 kpsi Actual: 5.6-5.7 kpsi
Hot. Desired: 4.3 kpsi Actual: 4.3 kpsi
Hot WOT: most I saw demanded 23.1 kpsi and actual would bounce around+/- 1kpsi

Baro Sensor: 14.6
Map at idle: 14 WOT:29

I was only able to get 15 psi from the turbo. This plus the lack of air at the MAF makes me lean towards a worn turbo, especially since it has 280,000 miles. Any thoughts?

2002 Chevy Silverado 2500HD
280,000 miles

Last edited by sahlers; 05-05-2015 at 12:43 PM.
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post #4 of 7 (permalink) Old 05-18-2015, 01:11 PM Thread Starter
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Still haven't solved it, but yesterday I found that my vacuum pump was only making about 6 in-Mercury when warmed up and held at 3000 rpms. From what I can find it is supposed to be at least 15 in-Mercury. Could this potentially be the root of my issue?

2002 Chevy Silverado 2500HD
280,000 miles
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post #5 of 7 (permalink) Old 12-12-2015, 05:55 PM Thread Starter
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Thought I should give a final update that I forgot to do. The vacuum pump did end up being the root cause of my issues. Replaced it and have been good to go since. It is a CA truck with all the smog equipment.

2002 Chevy Silverado 2500HD
280,000 miles
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post #6 of 7 (permalink) Old 07-15-2019, 01:36 PM
 
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I know this is an old thread, and no replies having same issues and wasn't aware there is a vacuum pump on my truck. also CA truck and completely stock with 133K miles looks like I will keep reading
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post #7 of 7 (permalink) Old 07-17-2019, 11:04 AM
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I posted a while back, maybe in the LLY forum, but I found a wire at the MAF connector that was broken inside the jacket.
Only found it when I tested each pin to ground. The resistance would jump all over and actually go open circuit when I wiggled the wire. Then it broke. Actually two of em broke.


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2003 Sierra 2500 Crew 4x4–Charcoal Grey Metallic
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