Shudder under light throttle...

[Baden]

Lately I have been noticing issues with the wife's rig (sig) and have searched on here but have not really found the answer(s). Under light throttle from a stop or changing a speed zone (say 25-35mph) under light throttle, the transmissions just shudders while accelerating, if I give it more or less it goes away. If I put my foot into it while pulling away from So from having previous issues with my 96 K1500, I figured maybe TCC issues, so I would tap the brake just make sure it isn't a lockup issue, doesn't seem mitigate the problem. Was wondering maybe if it was a (bad) spot in the TPS causing issues, but didn't see anyone having direct correlation with that on the forum or the webs, but have not tried this yet. Debated having the transmission serviced since the rig has 104k miles on it but I have heard horror stories of people coming out of the shop with worse symptoms than when they went into the shop. I have read a lot of threads about AFM causing issues as well. Really just no idea which approach to take.

Thoughts?

 

[Baden]

Lately I have been noticing issues with the wife's rig (sig) and have searched on here but have not really found the answer(s). Under light throttle from a stop or changing a speed zone (say 25-35mph) under light throttle, the transmissions just shudders while accelerating, if I give it more or less it goes away. If I put my foot into it while pulling away from a stop, zero issues...just seems to be a light throttle circumstance. So from having previous issues with my 96 K1500, I figured maybe TCC issues, so I would tap the brake just make sure it isn't a lockup issue, doesn't seem mitigate the problem. Was wondering maybe if it was a (bad) spot in the TPS causing issues, but didn't see anyone having direct correlation with that on the forum or the webs, but have not tried this yet. Debated having the transmission serviced since the rig has 104k miles on it but I have heard horror stories of people coming out of the shop with worse symptoms than when they went into the shop. I have read a lot of threads about AFM causing issues as well. Really just no idea which approach to take.

Thoughts?

Replied for editing purposes since it wouldn't let me edit the original post a second time...

 

[iamdub]

Press the top button of the DIC controls until it displays what cylinder mode it's in and drive to replicate the issue. When it shutters, don't accelerate any more or less, try to hold it steady and see if it's in V4 mode. You may have to accelerate ever so slightly to exacerbate the shuttering, just don't press the pedal enough to make it switch to V8 mode. If it shutters the whole time you're doing this, then press the pedal a little more to accelerate hard enough that it instantly smooths out. The DIC should indicate V8 mode within half a second or so. Repeat this test to confirm. If you can narrow it down this much, then at least you know it's the AFM system and not your trans.

 

[Baden]

Press the top button of the DIC controls until it displays what cylinder mode it's in and drive to replicate the issue. When it shutters, don't accelerate any more or less, try to hold it steady and see if it's in V4 mode. You may have to accelerate ever so slightly to exacerbate the shuttering, just don't press the pedal enough to make it switch to V8 mode. If it shutters the whole time you're doing this, then press the pedal a little more to accelerate hard enough that it instantly smooths out. The DIC should indicate V8 mode within half a second or so. Repeat this test to confirm. If you can narrow it down this much, then at least you know it's the AFM system and not your trans.

Played with this a little bit previously when it first started acting up and read about people having issues with AFM. I will look into it some more when I get a chance to spend some more time with it or when we drive it instead of the pickup. She is clueless to what is actually happening when it happens so having her check it for me is pointless.

Thanks for the input.

 

[hairscramlber]

Where is the indicator or light that tells you when the AFM goes into V4 and V8 mode. I cannot find it. Thanks in advance.

 

[PG01]

Afm doing it bud, my '13 used to do same all the time

 

[PG01]

Where is the indicator or light that tells you when the AFM goes into V4 and V8 mode. I cannot find it. Thanks in advance.

Scroll thru dic- top button- avg mpg will say v4 or v8

 

[Baden]

Afm doing it bud, my '13 used to do same all the time

You give me hope. lol

 

[hairscramlber]

AFM...It is horrible in its stock form.

 

[Dustinh]

Not sure if there is a difference but in my 02 mine had the same exact problem you're describing after having my trans rebuilt. Took it back to the guy that rebuilt it and he found that the valve in my trans was messed up so he replaced the valve and it's been fine ever since. Like I said I know yours is not an 02 but it was the same problem. Good luck