So i bought my 08 h3 about a month ago.. 75k miles. Im to the point of wanting to trade it in for something else if i cant find someone to diagnose my problem before my warranty is up! Its kinda difficult to explain if your not driving the car urself.. But im going to try my best! When i am driving at a speed of 50-70mph & let off the gas to coast, when i press the gas pedal again it seems to hesitate to pick back up to speed. If i need to lightly accelerate, the tachometer often bounces right on 2,000 rpms until it decides to smooth out or until i floor it. Sometimes it almost seems as if the rpms start surging.. Iv been running 93 in it for the past 2 weeks & cant tell any difference. Any advice would be greatly appreciated! Iv taken it to 2 dealerships, one said its just underpowered & other said i just may have a sensitive tach..... I understand im driving no race car.. But something just doesnt feel right!

 

Fuel injected vehicles periodically require that their Throttle Body and MAF be periodically cleaned. You can search how that here, or Google it.

You can look at this thread page 1 for a decent example. https://www.hummerforums.com/forum/h...ocedure-26706/

Buy a can of TB Cleaner and another can of MAF Cleaner and us ONLY that to do your cleaning. Instructions are on the cans, I prefer CRC products. NEVER touch the MAF sensor element with anything, just spray it off.



Your stock 08 PCM program is fixed to us 87 octane, anything higher just empties your wallet faster.

This may not cure your problem, it will help, and you should always start with the easy stuff. You might want to check the plugs to make sure it has ACDelcos in it, the prior owner might have though he/she was doing some upgrade by replaceing them with some fad aftermarket plug, and if you search the plug topic you will see that any plug other than the correct ACDelco irridiums is asking for trouble.

Your steelership guy that said the H3 is under powered, is under brained. Mine with mods can scorch Full Sized stock V8s and it weighs in at almost 6000# with me in it.

 

Agreed.
* sparks ac delco Del*41-103
* tb & maf
* check black small hose under resonator nearest rear of engine ...it should not be sloppy, loose, sponge, dry rotted or heat soaked damaged.
*place front wheels straight on to curb and put in gear and try to accelerate to see if trans is slipping.
* check air intake cover make sure it is tight
* replace fuel injectors
Any or all could be issue. Of course none also.

Chris

 

Thank yall! I will look into getting these things looked at! This chick isnt trying to mess anything up! Lol

 

Ive always used Seafoam to clean out my engine via poouring the Seafoam into the gas tank. Ive also used it by pouring it into the vaccum lines. Dont know how mechanically inclined you are but you can also look on youtube for "Seafoam Car Engine" and it should bring up a bunch of videos on how to clear out the gummed up Carbon in the engine. Ive had lots of good results just adding it to a tank of gas on several of my cars with similar symptoms.

 

I forgot to mention i did try the seafoam last week & havent noticed a difference! also seems as if it does it more often when im lower on gas.. Quarter of a tank or so. If thats even possible..

 

Sooo i just had the bright idea to shift out of "Drive" and into 3rd while driving.. And it ran like a different car! Felt way more responsive to my gas pedal (unlike usual), Didnt skip a beat, not even going up hills! (Which is when i often feel the original issue) Is it possible this could point to anything?! Something wrong with my overdrive?! Clueless here.. Help!!!

 

Have you changed the transmission fluid and filter yet?

 

I changed air filter. Havent done fluid yet! Or are you referring to fuel filter?

 

Doc is referring to the transmission filter.