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DTC P0107 #5002535
02/05/19 11:25 PM
02/05/19 11:25 PM
Joined: Jan 2018
Posts: 999
San Antonio, TX
das_peikko Offline OP
das_peikko  Offline OP

Joined: Jan 2018
Posts: 999
San Antonio, TX
MAP sensor voltage signal too low. I haven't done the powers and grounds test yet. I'm just throwing this out there in case somebody has had the code on their car. The engine is a 2000 Buick 3800 V6. The MAP sensor is not original; I replaced it about 3 years ago with an ACDelco unit. But when I replaced it 3 years ago, I had drivability issues but no code. This time I have a code, but the car drives fine.

Re: DTC P0107 [Re: das_peikko] #5002550
02/06/19 12:46 AM
02/06/19 12:46 AM
Joined: Dec 2013
Posts: 2,971
Fort Worth, Texas
clinebarger Offline
clinebarger  Offline

Joined: Dec 2013
Posts: 2,971
Fort Worth, Texas
When that DTC sets....The PCM ignores the MAP voltage & calculates base fueling & load off the MAF sensor. It just can't/won't update the learned Barometric Pressure value which will only be an issue if your driving in varying altitudes.

It's when the MAP voltage is within range, But reporting false pressure/BARO values that fueling gets out of wack. This vehicle doesn't support P0106 which is a MAP sensor performance/sanity check DTC that would have helped with the previous issue.


2001 Chevy Camaro L92/4L80E
2006 Chevy 2500HD LBZ/Allison 1000
2010 Toyota Corolla 2ZR-FE/U341E
2000 Toyota Avalon 1MZ-FE/A541E
Re: DTC P0107 [Re: das_peikko] #5002630
02/06/19 07:03 AM
02/06/19 07:03 AM
Joined: Oct 2018
Posts: 104
Michigan
Diesel12 Offline
Diesel12  Offline

Joined: Oct 2018
Posts: 104
Michigan
Which vehicle do you have? These are schematics for a 2000 regal 3800.

Capture.PNG

1998 Dodge Neon-Rebuilt 2.4L-Schaeffer 5w40
2014 Dodge Durango 3.6, 63K- Schaeffer 5w-20
2002 Ram 2500 Cummins 125K- Schaeffer 5w-40
2008 Dodge Avenger 226K Schaeffer 5w-20
Re: DTC P0107 [Re: clinebarger] #5003203
02/06/19 03:45 PM
02/06/19 03:45 PM
Joined: Jan 2018
Posts: 999
San Antonio, TX
das_peikko Offline OP
das_peikko  Offline OP

Joined: Jan 2018
Posts: 999
San Antonio, TX
I just now completed the test. Powers and grounds to the sensor are good. It's just a 3-wire sensor. 5V Reference, Signal, and Ground are all working fine. But what's unusual is the Signal Voltage at idle is low and unstable. The book says the Signal Voltage is supposed to be from just below 2V at idle to 4V at either wide open throttle or the Key On Engine OFF. What I'm getting at idle is anywhere from 1.06x volts to 1.09x volts. The numbers are jumping around too fast to read the third digit over from the decimal. Going above idle, the numbers are actually going down to as low as 0.940V and unstable. Key On Engine Off it varies from 4.803V to 4.811V. I erased the DTC to see if it comes back.

Re: DTC P0107 [Re: das_peikko] #5003509
02/06/19 10:12 PM
02/06/19 10:12 PM
Joined: Dec 2013
Posts: 2,971
Fort Worth, Texas
clinebarger Offline
clinebarger  Offline

Joined: Dec 2013
Posts: 2,971
Fort Worth, Texas
Do you have access to a scan tool that displays live data? I like to see what the PCM sees!
Let's say you have a open in the MAP signal circuit......The readings on the signal output at the sensor can be unstable because it's not connected to the Resisted Ground in the PCM. And the PCM will see Low/No Voltage!

Resisted Bias Powers & Grounds are utilized to smooth/stabilize sensor feedback circuits. Secondary Ignition is very good at inducing "noise" on precision low voltage electrical circuits!

Sounds like a bad MAP sensor, Just food for thought on the subject!


2001 Chevy Camaro L92/4L80E
2006 Chevy 2500HD LBZ/Allison 1000
2010 Toyota Corolla 2ZR-FE/U341E
2000 Toyota Avalon 1MZ-FE/A541E
Re: DTC P0107 [Re: clinebarger] #5003598
02/07/19 12:58 AM
02/07/19 12:58 AM
Joined: Jan 2018
Posts: 999
San Antonio, TX
das_peikko Offline OP
das_peikko  Offline OP

Joined: Jan 2018
Posts: 999
San Antonio, TX
No access to live data. The original MAP sensor that had an intermittent problem was caught by an oscilloscope. The oscilloscope was able to map out super fast variations in voltage changes. The volt meter shows the 3rd digit to the right of the decimal changing too fast to see. Your theory of secondary ignition noise disrupting the ground flow back to the PCM is interesting.

Re: DTC P0107 [Re: das_peikko] #5004378
02/07/19 09:25 PM
02/07/19 09:25 PM
Joined: Jan 2018
Posts: 999
San Antonio, TX
das_peikko Offline OP
das_peikko  Offline OP

Joined: Jan 2018
Posts: 999
San Antonio, TX
Check Engine light came back on tonight. I made a deal with my neighbor down the street. I knock down all his weeds in his yard and in return --- he puts the car on the scope Saturday. He's a GM drivability tech.

Re: DTC P0107 [Re: das_peikko] #5004453
02/07/19 11:10 PM
02/07/19 11:10 PM
Joined: Dec 2013
Posts: 2,971
Fort Worth, Texas
clinebarger Offline
clinebarger  Offline

Joined: Dec 2013
Posts: 2,971
Fort Worth, Texas
Originally Posted by das_peikko
No access to live data. The original MAP sensor that had an intermittent problem was caught by an oscilloscope. The oscilloscope was able to map out super fast variations in voltage changes. The volt meter shows the 3rd digit to the right of the decimal changing too fast to see. Your theory of secondary ignition noise disrupting the ground flow back to the PCM is interesting.


The PCM sends out a resisted ground bias on the MAP signal circuit to suppress noise, The resistance to ground is high enough that it won't affect any hard voltages produced by the sensor.

Not much need for a scope for this, Just make sure the PCM is receiving MAP voltage & wiggle the wiring at the MAP sensor while watching the MAP voltage PID to confirm you don't have a intermittent open or short to ground! However......We all have our ways of doing things!

IIRC....The set criteria for P0107 is voltage below .02 vdc which equates to a intermittent open, short to ground, Or a shorted sensor.


2001 Chevy Camaro L92/4L80E
2006 Chevy 2500HD LBZ/Allison 1000
2010 Toyota Corolla 2ZR-FE/U341E
2000 Toyota Avalon 1MZ-FE/A541E
Re: DTC P0107 [Re: das_peikko] #5008322
02/11/19 08:33 PM
02/11/19 08:33 PM
Joined: Jan 2018
Posts: 999
San Antonio, TX
das_peikko Offline OP
das_peikko  Offline OP

Joined: Jan 2018
Posts: 999
San Antonio, TX
I got the idea that maybe I should check the PCV valve since the MAP sensor sits directly on top of it. I pulled the PCV valve out and shook it. It felt kind of sticky with a film of oil on it, so I then submerged it in a jar of carburetor cleaner and shook it up in the jar. PCV valve rattles more freely now that it's clean. Reinstalled PCV valve. Check Engine light has since turned itself off.

Re: DTC P0107 [Re: das_peikko] #5008408
02/11/19 10:26 PM
02/11/19 10:26 PM
Joined: Dec 2013
Posts: 2,971
Fort Worth, Texas
clinebarger Offline
clinebarger  Offline

Joined: Dec 2013
Posts: 2,971
Fort Worth, Texas
The thing is.....P0107 set criteria is actually .01 vdc which would calculate out to @30 inches of vacuum.......That's impossible for your engine to achieve.


2001 Chevy Camaro L92/4L80E
2006 Chevy 2500HD LBZ/Allison 1000
2010 Toyota Corolla 2ZR-FE/U341E
2000 Toyota Avalon 1MZ-FE/A541E
Re: DTC P0107 [Re: das_peikko] #5008437
02/11/19 11:10 PM
02/11/19 11:10 PM
Joined: Jan 2018
Posts: 999
San Antonio, TX
das_peikko Offline OP
das_peikko  Offline OP

Joined: Jan 2018
Posts: 999
San Antonio, TX
Would a sticky PCV valve cause excess vacuum in the upper intake manifold, or not enough vacuum?

Re: DTC P0107 [Re: das_peikko] #5008459
02/12/19 12:20 AM
02/12/19 12:20 AM
Joined: Dec 2013
Posts: 2,971
Fort Worth, Texas
clinebarger Offline
clinebarger  Offline

Joined: Dec 2013
Posts: 2,971
Fort Worth, Texas
It could cause low idle vacuum readings, But never higher than normal readings.

The PCV inlet & MAP are open to the intake plenum & always at equilibrium. Servicing the PCV is never a bad thing.....I just don't feel that's the cause of your DTC.


2001 Chevy Camaro L92/4L80E
2006 Chevy 2500HD LBZ/Allison 1000
2010 Toyota Corolla 2ZR-FE/U341E
2000 Toyota Avalon 1MZ-FE/A541E
Re: DTC P0107 [Re: das_peikko] #5008834
02/12/19 01:04 PM
02/12/19 01:04 PM
Joined: Jan 2018
Posts: 999
San Antonio, TX
das_peikko Offline OP
das_peikko  Offline OP

Joined: Jan 2018
Posts: 999
San Antonio, TX
I'm thinking they must have put the MAP sensor on top of the PCV valve for a reason. And being that the PCV valve is directly below the MAP sensor, (might even be in direct contact) it must have an affect on it.

Re: DTC P0107 [Re: das_peikko] #5029417
03/02/19 06:37 PM
03/02/19 06:37 PM
Joined: Jan 2018
Posts: 999
San Antonio, TX
das_peikko Offline OP
das_peikko  Offline OP

Joined: Jan 2018
Posts: 999
San Antonio, TX
The new MAP sensor has been keeping the check engine light off. I got a new Delphi from Amazon.

At least I verified powers and grounds! Most people would have just thrown a new sensor at it.

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