I unplug the MAF Sensor, WHAT should the running engine do?

Air filter, throttle, sensors, vacuum, etc.
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tdrago
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I am merely driving my van
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I unplug the MAF Sensor, WHAT should the running engine do?

Post by tdrago »

Hi All! Searched as best I can but couldn't find an answer to this question. On a 2003 Astro w/ stock engine. Bought it with the evil P0300 code. Can do highway speed just fine but can feel some vibration as the engine runs a little "rough".
Trying to troubleshoot the P0300 DTC code. Engine starts easy. Runs pretty strong with just enough rumble/vibration to let you know somethings not quite right.
I was told by the seller that the MAF sensor was bad. Bought a new one and installed it. Made ZERO difference in how the engine runs.
I have found that with the engine running if I disconnect the MAF sensor plug the engine doesn't seem to run any differently. No surge, no stall, not shutting down, nothing, nada, zilch reaction.

The question is: ==> What SHOULD be the running engines reaction to unplugging the MAF from system? <==

I normally get no MAF related codes but if I unplug it I DO get a MAF related error shown so at least THAT part of the system appears to work.
Still doing other stuff to track down the p0300 problem but was hoping for some insight into the MAF's lack of influence on the engine. :-k
Thanks.
TD

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Re: I unplug the MAF Sensor, WHAT should the running engine

Post by Astrophysics »

Hi,

How many miles on vehicle?
Is there soot on exhaust pipe tip which could indicate running rich and perhaps bad fuel injection spider lines?
Or is it running lean due to dirty fuel filter?
If you have vacuum gauge, check manifold vacuum for 17 inch of Hg.


My 2003 Astro has 130,000 and I have been lucky with smooth engine.

Good luck.

AP

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Re: I unplug the MAF Sensor, WHAT should the running engine do?

Post by Bret Schmerker »

tdrago wrote: Wed Sep 19, 2018 1:35 am Hi All! Searched as best I can but couldn't find an answer to this question. On a 2003 Astro w/ stock engine. Bought it with the evil P0300 code. Can do highway speed just fine but can feel some vibration as the engine runs a little "rough".
Trying to troubleshoot the P0300 DTC code. Engine starts easy. Runs pretty strong with just enough rumble/vibration to let you know somethings not quite right.
I was told by the seller that the MAF sensor was bad. Bought a new one and installed it. Made ZERO difference in how the engine runs.
I have found that with the engine running if I disconnect the MAF sensor plug the engine doesn't seem to run any differently. No surge, no stall, not shutting down, nothing, nada, zilch reaction.

The question is: ==> What SHOULD be the running engines reaction to unplugging the MAF from system? <==

I normally get no MAF related codes but if I unplug it I DO get a MAF related error shown so at least THAT part of the system appears to work.
Still doing other stuff to track down the p0300 problem but was hoping for some insight into the MAF's lack of influence on the engine. :-k
Thanks.
TD
:smurf: I recognize the trouble code from my M11006; the computer throws P 0300 when it detects misfire in two or more cylinders. Related to ignition, not fuel. Last year, I had a sudden miss going to a job in Concord, CA, traced it to failed components in the secondary ignition (primary cause: failed distributor cap on the high-voltage switch). Still throws P 0305 under certain conditions; may have gotten a defective replacement distributor cap (viz., the #5 point having a hairline crack that would reveal itself only at idle), but cannot rule out the original ignition module having been taken out in the original sudden miss.
1997 GMC M11006 (Safari SLE, 2WD, V6-4300/4L60-E/7.625" 3.73:1 open)
Acquired Jul 2018 / In service Sep 2018 - present
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Re: I unplug the MAF Sensor, WHAT should the running engine do?

Post by WoodButcher »

https://autoguysland.com/what-happens-i ... ow-sensor/

I just googled, an interesting read.
'97 Safari, 290,000 miles,,, retired
'93 Safari shorty, 350 swap my new daily
'02 Astro, my non working work van. Waiting for a V8
'69 G10, straight 6, 3 onatree, jumped at me when I had a pocketful of cash looking for a spare astro. :)

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Re: I unplug the MAF Sensor, WHAT should the running engine do?

Post by Astrophysics »

Hi,

Just found Volant Performance air intake kit #25743 for 4.3 l Astro. $203.
The www.volantperformance.com set show a photo of this air filter kit on an Astro.

Interesting.

The K &N kit 57-3017-2 fits S10 truck but not exact fit for Astro. k&N claims 7.42 hp increase at 4671 rpm.



AP
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Re: I unplug the MAF Sensor, WHAT should the running engine do?

Post by WoodButcher »

A.P.,
When is the last time you had your astro to 4500 RPM?

You see most of the things like this are unsuited for our uses. Your rig is setup for off road use mostly correct? Which would be better for you if you're out boondocking and have trouble with a dirty air filter? Are you likely to have the things to clean an oil filter or have a spare oiled filter handy? A spare stock is convenient and clean if you needed to carry it along.
And where is that 7 hp useful? maybe when you kick it down on the highway for passing, maybe...
'97 Safari, 290,000 miles,,, retired
'93 Safari shorty, 350 swap my new daily
'02 Astro, my non working work van. Waiting for a V8
'69 G10, straight 6, 3 onatree, jumped at me when I had a pocketful of cash looking for a spare astro. :)

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Re: I unplug the MAF Sensor, WHAT should the running engine do?

Post by Astrophysics »

Howdy,

Yup, good points. The cleaning and oiling of K&N filter is a hassle. I better stick with Wix or AC standard air filters like you suggest.

Thank you,

AP

Bret Schmerker
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Re: I unplug the MAF Sensor, WHAT should the running engine do?

Post by Bret Schmerker »

Bret Schmerker wrote: Sat Sep 18, 2021 2:17 pm
tdrago wrote: Wed Sep 19, 2018 1:35 am Hi All! Searched as best I can but couldn't find an answer to this question. On a 2003 Astro w/ stock engine. Bought it with the evil P0300 code. Can do highway speed just fine but can feel some vibration as the engine runs a little "rough".
Trying to troubleshoot the P0300 DTC code. Engine starts easy. Runs pretty strong with just enough rumble/vibration to let you know somethings not quite right.
I was told by the seller that the MAF sensor was bad. Bought a new one and installed it. Made ZERO difference in how the engine runs.
I have found that with the engine running if I disconnect the MAF sensor plug the engine doesn't seem to run any differently. No surge, no stall, not shutting down, nothing, nada, zilch reaction.

The question is: ==> What SHOULD be the running engines reaction to unplugging the MAF from system? <==

I normally get no MAF related codes but if I unplug it I DO get a MAF related error shown so at least THAT part of the system appears to work.
Still doing other stuff to track down the p0300 problem but was hoping for some insight into the MAF's lack of influence on the engine. :-k
Thanks.
TD
:smurf: I recognize the trouble code from my M11006; the computer throws P 0300 when it detects misfire in two or more cylinders. Related to ignition, not fuel. Last year, I had a sudden miss going to a job in Concord, CA, traced it to failed components in the secondary ignition (primary cause: failed distributor cap on the high-voltage switch). Still throws P 0305 under certain conditions; may have gotten a defective replacement distributor cap (viz., the #5 point having a hairline crack that would reveal itself only at idle), but cannot rule out the original ignition module having been taken out in the original sudden miss.
:-({|= Welp, defective distributor cap ruled out - probably a failing ignition module. Would BOSCH® still made the aircraft-stye IR-Fusion™ in 14mm - four ground points to take the spark from the center towerlet.
1997 GMC M11006 (Safari SLE, 2WD, V6-4300/4L60-E/7.625" 3.73:1 open)
Acquired Jul 2018 / In service Sep 2018 - present
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