if the problem only occurs when transitioning from idle to off idle try a throttle body clean. This is a cheap and easy procedure you can do yourself...but you will need a scan tool to perform and idle relearn afterwards


Is this a flex fuel vehicle?
What are the fuel trims reading at idle and 2500rpm?

 

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Iron Bear,
Any updates? I have the same issues in a 2010 yukon 4x4. Dealer always says its normal due to "active fuel management" but I find that hard to believe.

 

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I cleaned the throttle body but it's still bucking and hesitating under light to moderate throttle. It's VERY bad when I'm towing.

This is NOT normal behavior. I've owned many vehicles over the year, and was a former master Toyota technician so I know what I'm talking about.

These dealers keep putting the truck on a computer to say 'there are no codes', well the issue is probably NOT in the computer. I've had it...

 

If it happens worse when you're towing, then bring a trailer to the dealer and take the tech for a ride and show him what it does. Things I'd check, fuel pressure during when the problem is happening, if the torque converter is partially applying causing a chugging sensation, if perhaps the TPS sensor is going out and the throttle is flutterying perhaps. There are things the technicians can check, but they'll only do so if you can demonstrate the problem to someone. If they cannot duplicate the concern, they're basically shooting in the dark.

 

what are the fuel trims reading during the acceleration? What is the fuel alcohol sensor reading? the alcohol content sensors do go askew;. and then fuel trim adjustments over compensate.

 

Condition/Concern
Some customers may comment on a sag or hesitation when accelerating under the following conditions:

When coasting at low speeds of less than 15 miles per hour with a closed throttle and then aggressively applying the throttle. Examples of this maneuver include a rolling stop or a lane change maneuver. In this type of maneuver, even though the accelerator is applied aggressively, the throttle blade is opened slowly for up to 0.7 seconds to help minimize drive-line lash and clunking.

Also in a vehicle equipped with a six speed automatic transmission when making a hard, complete stop with a closed throttle, immediately followed by an aggressive throttle opening the transmission down-shifts may not be completed by the time the throttle is opened. As a result approximately 0.5 seconds of ″zero″ torque may be commanded to allow the shift to first gear to occur.

Recommendation/Instructions
Both of the above conditions are a result of Torque Management and both of these conditions should be considered normal and no repairs should be attempted

 

I don't own a meter reader so I couldn't tell you what the readings are.