[srmollard]

I have a 2008 Chevy Colorado I4, manual transmission. For the last couple of years (pretty much since I bought the vehicle), I will randomly get a hesitation in the middle of the acceleration in my lower gears. It will start to move, then partway in the acceleration it will feel like the truck almost stalls, sometimes repeatedly, but if I feather the gas a bit then it will kick up just fine and go back to normal. Once up to speed the truck seems to run just fine. No check engine lights.

This only happens randomly, not consistently and I can't repeat it when I want to. I did notice it usually happens on hot days, but has happened on a cold morning or two. For example, it has run fine here in Colorado all winter, but yesterday it was the warmest it has been in a while (high 70's) and this hesitation happened to me twice on my drive home from work. Today it is snowing and everything is fine. Other times it can be in the 90s all week and run fine.

So far I have replaced spark plugs and ignition coils, but havent done much else as I have had bigger fish to fry on other vehicles. I think I am going to clean the MAF sensor next, and I saw a post mentioning the vapor canister so I will clean that and make sure the vent is working properly. Like I said though, no check engine lights and no idling issues, so I am not sure where else to look. Any suggestions?

 

[Kenzen]

Clean the MAF, which is also the intake air temperature sensor - either of these can screw up your A/F mixture and give you these hesitations. See if it goes away with the A/C turned off if you've been running it.

 

[srmollard]

Thank you for the quick response, I will give that a try and see what happens. I thought the same about the a/c. I am pretty sure it happened to me when it was off last summer. I turned it off during one of the weeks where it was happening to me every day. But yesterday was the first day I used A/C and it was the first time I have had it hesitate in months. I’ll clean the MAF first and if that doesn’t work I’ll drive with the windows open for a while to see if it disappears.

 

[Colly_shifter]

Try checking at your MAP sensor too, the one on top of the engine near the intake manifold. (right after the throttle body)

Try wiggling it while the engine is running and see how bad it stumbles, if at all. Typically I would put some electrical tape around the securing clip to make sure the sensor is in it's socket well and not able to move around period.(haven't done this on my new truck yet)

If it nearly tries to die while doing this, I'd look hard at either replacing the sensor itself (not terribly expensive) or if the wiring is old, faded and frayed looking, the whole MAP sensor plug itself as well, if replacing the MAP does not fix it.

That sensor is quite finicky too, a frayed wire connecting to it or a failing MAP sensor can do all kinds of "fun" stuff with your engine's idle and WOT response. Ask me how I know! facepalm

Hope this helps, good luck!

 

[srmollard]

I cleaned off the MAF last night and will be checking the MAP sensor this weekend just in case. No issues today, but I will keep you updated as the weather is supposed to be warm this weekend!

 

[OldGuy]

While you're at it, I'd go ahead and remove a clean the the throttle body too. That always makes my '04 run better.

 

[R1cky_bobby79]

I'm experiencing the same issue. 2005 3.5 seems to hesitate and acceleration kicks in and out after sitting in traffic. Once moving its fine. It did shut off on me as well. But will start right back up. Any insight?

 

[srmollard]

So far I have tried what is mentioned above with the MAF and the MAP. Unfortunately I have been traveling for work all week so I haven’t had much of a chance to test it out, but it hasn’t hesitated the few times I have driven since after doing those.