Oil sensor casues shake/studder. Please help

[Dj Will]

 

[iamdub]

@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.
View attachment 260208 View attachment 260209

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

View attachment 260210 View attachment 260211 View attachment 260212

I would disable AFM ASAP. Keeping it from activating will at least prolong the almost guaranteed failure. I can guarantee won't miss it living in Dallas. You can buy a Range plug-in disabler for about $200 new or ~$100-$150 used, a handheld tuner that has disabling capabilities for a few hundred, a custom tune from ~$100 to over $500 to disable it and tweak a bunch of other items to improve the power and shifting (and prolong trans life) or, if you can wait a few days, send the PCM to this guy and have it turned off for $50. If you're not interested in having anything else tweaked in the tune, this would be the best way to go. If you ever decide to mechanically delete AFM (replace cam and lifters with non-AFM parts, etc.), you won't need to have the PCM flashed to get it running.


I have a Welly 2008 Tahoe LT die cast 1:24 model. It's black and, after modding the body, I plan to paint it Graystone Metallic and lower it. Finding wheels similar in design and scale size to whatever 22s I settle on would be a bonus. The model I have is pretty much YOUR Tahoe! This one: https://www.amazon.com/Welly-Chevro...ecast&qid=1602885923&s=toys-and-games&sr=1-11

 

[iamdub]

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

I know the system mechanically operates by oil pressure, but couldn't figure out what the PCM reading the oil pressure from a different sensor would have to do with anything. Obviously, it has to know the pressure to meet one of the parameters required for operation. But- a change in the sensor affecting this? My cynical side is wondering if they altered the newer sensors to read differently, as in to make the pressure read a little higher than it actually is to keep us happy. Also, if the PCM is seeing (falsely) higher pressure, would this make it keep AFM engaged for longer than it should be?

@Dj Will, did you happen to notice if the oil pressure on the gauge read a little higher with the new sensor(s)? Or, with the new sensor(s), does it switch back to V8 mode at a higher RPM when slowing to a stop?

 

[Dj Will]

I know the system mechanically operates by oil pressure, but couldn't figure out what the PCM reading the oil pressure from a different sensor would have to do with anything. Obviously, it has to know the pressure to meet one of the parameters required for operation. But- a change in the sensor affecting this? My cynical side is wondering if they altered the newer sensors to read differently, as in to make the pressure read a little higher than it actually is to keep us happy. Also, if the PCM is seeing (falsely) higher pressure, would this make it keep AFM engaged for longer than it should be?

@Dj Will, did you happen to notice if the oil pressure on the gauge read a little higher with the new sensor(s)? Or, with the new sensor(s), does it switch back to V8 mode at a higher RPM when slowing to a stop?

I didn't notice if the gague reading was any higher. I think im going to see if my local performance shop can delete the AFM.

Thank you all for the kick ass help. I'll definitely keep everyone posted.

 

[1BADI5]

View attachment 260241 View attachment 260242

Never buy Dorman sensors........their quality control is garbage.

Hope that didn't make me sound like a *****........but they will cost you more money in the end then having bought OEM parts

 

[wjburken]

Never buy Dorman sensors........their quality control is garbage.

Hope that didn't make me sound like a *****........but they will cost you more money in the end then having bought OEM parts

I agree that Dorman is not what you want for an oil sensors, but I think the Dorman packaging you see in his picture is for oil pressure sensor screen - Not the Sensor. He bought an AC Delco sensor from AutoZone per his first post.

 

[1BADI5]

I agree that Dorman is not what you want for an oil sensors, but I think the Dorman packaging you see in his picture is for oil pressure sensor screen - Not the Sensor. He bought an AC Delco sensor from AutoZone per his first post.

Gotcha, I was just speaking in general

 

[QDaddy]

My 2008 5.3 started doing this last week and I figured it was the torque converter and old tranny fluid. I have a hard 1-2 shift, so I was going to do a change/flush, replace the TPS, 1-2 accumulator and corvette servo. I'll diag the AFM switch tomorrow and see if it comes up. I just started using a fully synthetic right before the shudder, so it makes a bit of sense. I've been sweating a new 4L60 for days.

 

[2011TXDenali]

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.

Sorry to bring up an old thread, but did you ever resolve this issue? I have the same thing going on in my Yukon. I replaced the oil pressure sensor about a year ago but had this shudder problem when slowing down/coming to a stop around 1K even before I got the error code and replaced it.

 

[iamdub]

Sorry to bring up an old thread, but did you ever resolve this issue? I have the same thing going on in my Yukon. I replaced the oil pressure sensor about a year ago but had this shudder problem when slowing down/coming to a stop around 1K even before I got the error code and replaced it.

That's just AFM staying engaged for too long. My '08 did that and the oil pressure sensor, gauge, etc. all worked perfectly fine. You could replace the VLOM. There's an updated design but yours, being a 2011, might would have it already. Honestly, I'd have AFM disabled. It'd be much less than the cost of a VLOM.