Engin seems to stutter on slight incline

[nickledimed]

08 Equinox, 3.6 l
While traveling on a sight incline, the auto seems to stutter and loose power, while trying to maintain speed.
Sometimes it will do this on a slight incline trying to gain speed while merging or passing.
No engine light.
The dealership says they have changed the plugs and coil packs.
I noticed that someone has put on 235/75R16 and they should be 235/65R16, throwing the speedo off about 3 mph.

Any ideas, why the car keeps stuttering?
No, I am not taking it to a speach therapist....

[maxwedge]

No check engine lite? Any pending codes?

[nickledimed]

I will have it checked. but the last one was # 3 miss fire and that is when they supposedly checked the spark plugs and found they were good and replaced the coil pack/s? Im not sure if they changed them all, I will cask them that, as well.
Thanks

[Ruley73]

Originally Posted by nickledimed

I will have it checked. but the last one was # 3 miss fire and that is when they supposedly checked the spark plugs and found they were good and replaced the coil pack/s? Im not sure if they changed them all, I will cask them that, as well.
Thanks

Are you sure about the engine size? I ask because some of the information you provided is contradictory. The 3.6L engine and 6-speed auto transmission was exclusive to the Sport trim which also only came with 18" wheels & tires (you said yours had 16" tires). All other trims (LS, LT, LTZ) came with a 3.4L engine & 5-speed auto transmission and 16" or 17" wheels.

If you have the 3.4L, that engine still uses spark plug wires which is most likely the source of your misfire. I would hope the dealership changed the wires before replacing the coils. The coils very rarely fail on the 3.4L engine.

[nickledimed]

Ruley73, you are right, it is a 3.4 Sorry about that.
Anyways, I stopped at Orielys and they received a code "random Misfire"
As Cheap as the wires are, I will go ahead and change them.
Thanks for the feed back Ruley73.

PS, I bought the car from Car Mart, so that should answer a lot of questions....

[nickledimed]

Issue has been fixed.
The dealer put a scanner on it and found the #2 cylinder was mis-fireing.
They went ahead and changed all plugs and he said he changed one of the wires.
Been driving for about a month now and the issue has not presented its self.
I am pretty please with the performance of the 3.4.
I have had them before but not as aggressive and this.