2017 Yukon hesitating/shuddering

[jyi786]

I'm having a very very similar issue in my 2019 Escalade ESV, so I'll be watching this thread. I know we have very different transmissions, but the symptoms are SPOT ON almost exactly the same.

On a side note, @Td_symmons what bi-directional scan tool did you use to get those graph screenshots?

 

[Td_symmons]

a physical gauge is best to rule it out for sure, just stick it up under the hood so you can see it through the window
and may as well do a fuel pressure drop test at the same time since you replaced the injectors

Great. Will do. Thanks!

@jyi786 great, hopefully we can get this sorted out together. I use my Autel mk808. I switched from autoenginuity in 2022. I really don’t like the Autel, but it’s one of the most cost efficient modern scan tools that had the functions I was looking for (had to include GM injection pressure drop testing).

 

[JrKinger]

So just had the same issue thought it was the the torque converter again. Took it to my mechanic who is great and he said all he could feel was the afm kicking in and out causing the shuddering and hesitation. So he deleted the afm and so far seems to have went away. It’s only been a week though so still need to see on a longer trip this week.

 

[Td_symmons]

So just had the same issue thought it was the the torque converter again. Took it to my mechanic who is great and he said all he could feel was the afm kicking in and out causing the shuddering and hesitation. So he deleted the afm and so far seems to have went away. It’s only been a week though so still need to see on a longer trip this week.

Great to know! I’ll see if I can do a test drive with AFM disabled

 

[trottida]

While I'm not familiar with the 2017 AFM, on the 2011's there is a screen in the driver center which shows you real time fuel mileage, within that screen it will show you if you are in 8 cyl or 4 cyl mode. If the shutter occurs when you are in 4 Cyl mode then it's likely your AFM system causing the shutter feeling until you apply enough throttle to kick it into 8 cyl mode. You mentioned disabling AFM - is that an option in the 2017's? I had to buy a Range AFM/DFM Disabler to do that.

 

[Doubeleive]

While I'm not familiar with the 2017 AFM, on the 2011's there is a screen in the driver center which shows you real time fuel mileage, within that screen it will show you if you are in 8 cyl or 4 cyl mode. If the shutter occurs when you are in 4 Cyl mode then it's likely your AFM system causing the shutter feeling until you apply enough throttle to kick it into 8 cyl mode. You mentioned disabling AFM - is that an option in the 2017's? I had to buy a Range AFM/DFM Disabler to do that.

it is not a oem option to turn it off on any of these vehicles. requires a tune out or removal of the components, the range device works but only does 1 thing for a little bit more you can get a lot more features.

 

[trottida]

it is not a oem option to turn it off on any of these vehicles. requires a tune out or removal of the components, the range device works but only does 1 thing for a little bit more you can get a lot more features.

That's what I thought regarding AFM disable. In my case I don't drive our Suburban enough to care about the extra options from a tune out. It's just a weekend vehicle to get back to our cabin pulling a trailer and/or a third vehicle to use in a pinch. I just wanted to get rid of the annoyance of the shutter in 4 cyl mode. I hope the Range device doesn't have any long term negative affects though. Time will tell.

 

[Doubeleive]

That's what I thought regarding AFM disable. In my case I don't drive our Suburban enough to care about the extra options from a tune out. It's just a weekend vehicle to get back to our camp pulling a trailer and/or a third vehicle to use in a pinch. I just wanted to get rid of the annoyance of the shutter in 4 cyl mode. I hope the Range device doesn't have any long term negative affects though. Time will tell.

no the only things I have ever seen is a few random reports of battery drain or the product failing over a period of time
and it appears that if you require a state vehicle inspection that checks smog equipment then it should be removed a couple weeks prior to inspection so all the sensors can set properly
disabling the afm in general is a benefit no matter how. other than a tiny mpg hit which can be extremely negligible.

 

[jyi786]

In my case, I'm 99% sure the shuddering has nothing to do with AFM. The truck goes in and out of V4/V8 mode seamlessly.

 

[Td_symmons]

In my case, I'm 99% sure the shuddering has nothing to do with AFM. The truck goes in and out of V4/V8 mode seamlessly.

I did multiple test drives last night. On one of them I monitored and reviewed almost every parameter related to the the AFM. Cylinder deactivation was never engaged when I was having the issues. No faults occurred. Both the dash and the parameter agreed that it was in v8 during the shake. I have noticed that it occurs close to 90% engine load and above.

I haven’t yet connected my fuel pressure gauge to verify that the (low pressure) fuel pressure sensor is accurate. I verified in the service manual that the measured fuel pressure is the output of the fuel pressure sensor near the tank, after the pump. The commanded fuel pressure is a separate parameter labeled “desired fuel pressure”.

During another test drive, I got a p0300 with a flashing MIL. Freeze frame data showed no misfires(?) - a test drive watching misfire data showed just a few small misfires here and there. Report and screenshots of misfire data at time of shake are attached.