Weird Truck Behavior

[Meccanoble]

Recently, when me or my girl drive the Tahoe, it shows a weird behavior and I'm trying to track it down so I know what to replace. All fluids except coolant has been changed. At first I thought my tranny was slipping but now I wonder if its something else.

Tranny - one time driving in the rain, the rpms go up but i wouldnt feel the power behind it. I'm thinking tranny slipping but no other symptoms. Definitely wasnt slipping in the rain, 95% sure. Tranny fluid changed 20k miles ago and the tranny temp was low ( under 140). I turned car off and let it sit for a short while after and this type of behavior stopped.

From time to time, I can feel a hesitation from the engine as if something holding it back and the only other major thing I never changed since owning roughly 25k miles ago is spark plugs and not sure when they were changed. I havent floored the truck since seeing these behaviors. No CEL light or anything but will go to see if a hidden code is listed. Any suggestions on what to look for? At idle car doesnt make any funny noises. Belts never changed since owner ship but show no issues. I see no crazy wobbles.

I know how the car is supposed to drive and something feels different. I am somewhat familiar with bad spark plug issues where rpms drop a little or do some hesitation and I think that is what I see at idles and driving sometimes...

 

[Meccanoble]

After further testing, found a few things.

Issue is when low pressure applied on gas pedal while car is already moving, the car does this hesitation where it won't accelerate that well. This always happens around 1700 rpms. When going hard, there seems to be no issues. Basically happens when cruising and trying to slightly increase speed.

I'm guessing it's either spark plugs or afm related? Black bear tune is the best option?

 

[Meccanoble]

Appreciate any feedback or direction

 

[Brian Wilson]

I would think about wheel speed sensors or throttle body. Easy enough to test both with a good scanner

 

[Meccanoble]

thanks for suggestion Brian. This 'scanner' is a CEL scanner or something different? I can eliminate spark plugs since its not consistent through various accelerations? AFM out of the question too? Throttle probably needs cleaning?

 

[Meccanoble]

Can anyone confirm what 'scanner' i need to check with, a standard CEL scanner at Autozone type thing?

 

[PG01]

My 13 does same 'hesitation thing' no slippage feeling tho. If no cel not sure autozone will see 'hidden codes' but ive gone there for that. Coasting in v4 with afm will do the hesitation and throttle cleaner is cheap enough and will help. Range afm disabler and cleaning mine throttle body helped but i am saving $ for bb tune and true afm/dod delete

 

[Meccanoble]

My 13 does same 'hesitation thing' no slippage feeling tho. If no cel not sure autozone will see 'hidden codes' but ive gone there for that. Coasting in v4 with afm will do the hesitation and throttle cleaner is cheap enough and will help. Range afm disabler and cleaning mine throttle body helped but i am saving $ for bb tune and true afm/dod delete

The slippage thing doesnt seem to happen anymore after that first time and makes me wonder if I even had one to begin with. All my issues happen in V8 mode between 1.5-2k rpm. Though I'm tapping the gas pretty lightly, I tend to average about 10-12 mpg when this issue happens according to dash.

Also, the car never goes in V4 mode unless i'm cruising with no acceleration. The second I touch the pedal the slightest, it goes into V8. So far, this happens no matter what speed. Normally at what point is V8 supposed to kick in or how can I see car in V4 mode with actual acceleration. I was thinking a 20%< throttle or similar would keep it in V4 mode.

 

[PG01]

No acceleration at all, basically coasting, is when mine goes into v4..... before the range

 

[Meccanoble]

No acceleration at all, basically coasting, is when mine goes into v4..... before the range

What is the point of that? No matter how conservative you want to drive, you normally need a little gas to maintain your speed. I thought it was based on low pressure on gas pedal, not no gas pedal at all. I'm still learning about AFM but if thats the only time it comes on, how does it become annoying and in the way?