Oil sensor casues shake/studder. Please help

[Dj Will]

A few weeks ago the check engine light came on. I checked the code and it turned out to be the oil pressure sensor. Went to autozone and the gave me an ACDELCO ACD#D1846A GM#12616646. I installed the sensor installed and the gague went back to work, but I started to notice a shake/studder as the truck would come to a stop; right around between 500-1K RPM. Mind you the only work the truck had was the replacement of the sensor, with that in mind I took the senor back out as some people suggested that they had "bad" new sensors sold in the past. I installed the original sensor as I order a new ACDELCO and it was being shipped. The shake/studder went away. This told me right away that issue was the sensor. Fast forward to receiving the new sensor. I now received an ACDELCO GM# 12677836. I figured that perhaps the autozone dude sold me the wrong part. I installed the new sensor and the shake is still there. I'm really confused and frustrated. I've researched what feels like the whole internet and have come empty handed.
Has anyone experience anything similar to this "Shake/Studder and that RPM range? Multiple sources show both sensor parts to be correct for an 08 5.3l Tahoe. Which is the right one?
The truck has no rough idle issues. She sit peacefully, even when accelerating.The shakes don't hit her until she is near a stop. Any idea what this could be?
Well thanks in advance. I hope someone can help out.

Its a 2008 5.3L Tahoe.

 

[wjburken]

A few weeks ago the check engine light came on. I checked the code and it turned out to be the oil pressure sensor. Went to autozone and the gave me an ACDELCO ACD#D1846A GM#12616646. I installed the sensor installed and the gague went back to work, but I started to notice a shake/studder as the truck would come to a stop; right around between 500-1K RPM. Mind you the only work the truck had was the replacement of the sensor, with that in mind I took the senor back out as some people suggested that they had "bad" new sensors sold in the past. I installed the original sensor as I order a new ACDELCO and it was being shipped. The shake/studder went away. This told me right away that issue was the sensor. Fast forward to receiving the new sensor. I now received an ACDELCO GM# 12677836. I figured that perhaps the autozone dude sold me the wrong part. I installed the new sensor and the shake is still there. I'm really confused and frustrated. I've researched what feels like the whole internet and have come empty handed.
Has anyone experience anything similar to this "Shake/Studder and that RPM range? Multiple sources show both sensor parts to be correct for an 08 5.3l Tahoe. Which is the right one?
The truck has no rough idle issues. She sit peacefully, even when accelerating.The shakes don't hit her until she is near a stop. Any idea what this could be?
Well thanks in advance. I hope someone can help out.

Its a 2008 5.3L Tahoe.

Welcome to the forum from Iowa.
I have never heard of an Oil Sensor causing any issues with the performance of a motor.
What was the code that AutoZone said you had that indicated the need for a new oil sensor? Did you verify that you had good oil pressure with an analog pressure gauge?
When you replaced the sensor, did you clean out the screen that is right below it?
Is AFM still enabled in your vehicle? If so, change your DIC to the screen that shows if you are in V8 or V4 mode and watch to see if the shudder coincides with when the vehicle shifts form V8 to V4 or vice-versa.
What is the condition of your transmission fluid?

If you can share a little bit more about your vehicle, that would help as well. Looking for things such as mileage, any recent work of any kind done to it in the last few months, last oil change, how old the plugs and wires are, etc.

 

[iamdub]

This really sounds like the shudder these get when the AFM "hangs" for a little too long, as Wade was leading to. I agree- watch the DIC screen that shows V8 or V4 mode as you cruise about 15mph then slowly come to a stop. See if it's in V4 mode when the shuddering starts then immediately stops when it switches to V8 mode.

The other half of this is what da hell does the oil pressure sensor have to do with the AFM "hanging"? Maybe the system is getting an inaccurate reading from the old sensor and it disengages AFM sooner, before you're at an RPM too low to shudder?

Mine had these same symptoms years ago so I had AFM disabled in a tune, then fully deleted recently.

BTW, @Dj Will, are those model Tahoes in your avatar? Have any better pics?

 

[OR VietVet]

Welcome to the forum @Dj Will.

I thought I read recently about oil draining down and getting in to the knock sensor at the rear area of the passenger side above the starter but it may have nothing to do with this problem. So glad I don't have to deal with AFM.

 

[Joseph Garcia]

Welcome to the Forum from NH.

Lots of knowledgeable folks here who freely share their knowledge, experiences, and perspectives. Knowledge is power.

You are already receiving solid feedback from the members of this Forum.

I hope that you will become a participating member in the Forum's discussions.

Pics, please.

 

[Dj Will]

@wjburken @iamdub @PNW VietVet @Joseph Garcia Amazing! You guys rock! Thank you so much for the prompt replies; talk about a kick ass community. So glad I found the forum.


@wjburken @iamdub I took her out for a drive and followed your instructions and sure enough the shudder kicks in when it goes from V8 mode to V4, right about 1000RPMs. I’m more confused now like @imadub said what does a new sensor have to do with the AFM? Does the computer have to relearn a new sensor? is getting the AFM disabled something I can do or I need to take it in?

I wanted to test my theory one more time today. So I unplugged the sensor, of course it spit out P0522 right away. I drove it a few miles and no shakes. Can it be that I have another bad sensor? Anybody know what the difference is between ACDELCO GM# 12677836 and ACDELCO GM#12616646


The truck is a 2008 LT with 160K. The truck has been kept up and never abused. Heck I get crap from my wife for driving so slow. Oil change just a few months ago and new plugs and wires back in Feb. Everything was fine until the sensor was replaced.


She is stock other then rims and black out taillights.


@iamdub Yes, both are diecast models. Here are some better pics.

 

[wjburken]

Will,

I agree, this forum is full of some pretty smart guys. I am just glad they let me hang out with them.

I am at a loss as to how the Oil Pressure Sensor would have an impact, but I am not going to claim to understand all the inner workings of the AFM control system on these rigs. One thing to check is there is a screen under your oil pressure sensor that frequently gets gunked up and can cause your oil pressure sensor to not see the correct oil pressure. Might see if you can find someone with skinny and flexible arms to remove the sensor and pull out that screen to see if it is indeed starting to plug up.

As for the difference in the two AC Delco part numbers, the sensor that RockAuto shows for your truck is AC Delco OEM #12677836. I am not sure the fitment of 12616646. Which one do did you put in?



BTW - Pretty cool Die Cast Tahoes you have there.

 

[OR VietVet]

This shows what the screen looks like.

https://www.rockauto.com/en/moreinfo.php?pk=320055&cc=1441040&jsn=1698

 

[1BADI5]

AFM works/operates via oil pressure.

The signal from the oil pressure sensor feeds those reading to the PCM and in turn the PCM sends a signal(s)/command(s) to either activate or deactivate the AFM solnoids which are part of the VLOM (under the valley cover).

I would also advice the OP to check the screen under the oil pressure sensor to verify its clean and not clogged up. This can be a pain in the dick if you choose to do it w/o removing the intake manifold.

Secondly, highly recommend checking the valley cover bolts ( there are 11 of them, size 13mm), to complete the procedure you would need to remove the intake manifold to access all 11 bolts. Its been well documented they can either come loose or were not properly torqued when the engine was assembled at the factory. These loose valley bolts can cause a loss of oil pressure and the VLOM will not operate correctly or as desired. (NOTE: ensure to torque the valley bolts in the correct order to ensure proper sealing of valley gasket and oil passages)

To replace the valley cover gasket will require disassembly of the VLOM to replace, not hard, but attention to detail is imperative.

These are some simple procedures that can be done at home w/o blowing several hundred dollars for a shop to diagnose.......because more then likely you will not have a CEL/MIL under these conditions. I have dealt with and serviced all of these issue in the last several months either on my personal truck or customer vehicles.

Food for thought and hope this helps. Cheers

 

[Dj Will]

AFM works/operates via oil pressure.

The signal from the oil pressure sensor feeds those reading to the PCM and in turn the PCM sends a signal(s)/command(s) to either activate or deactivate the AFM solnoids which are part of the VLOM (under the valley cover).

I would also advice the OP to check the screen under the oil pressure sensor to verify its clean and not clogged up. This can be a pain in the dick if you choose to do it w/o removing the intake manifold.

Secondly, highly recommend checking the valley cover bolts ( there are 11 of them, size 13mm), to complete the procedure you would need to remove the intake manifold to access all 11 bolts. Its been well documented they can either come loose or were not properly torqued when the engine was assembled at the factory. These loose valley bolts can cause a loss of oil pressure and the VLOM will not operate correctly or as desired. (NOTE: ensure to torque the valley bolts in the correct order to ensure proper sealing of valley gasket and oil passages)

To replace the valley cover gasket will require disassembly of the VLOM to replace, not hard, but attention to detail is imperative.

These are some simple procedures that can be done at home w/o blowing several hundred dollars for a shop to diagnose.......because more then likely you will not have a CEL/MIL under these conditions. I have dealt with and serviced all of these issue in the last several months either on my personal truck or customer vehicles.

Food for thought and hope this helps. Cheers

Great Information thanks.

I've replaced the screen twice as I tore the first one pull it out.

View attachment 260240

I just pulled out the sensor and check out the difference
View attachment 260239
The one on the right is the new ACDELCO, the left is what was originally in the truck. Do you guys think this can effect it?