Engine Missing or Cruise Control Issue?

[Marc Marc]

My 2013 Yukon Denali Hybrid (187k miles) feels like the engine is stuttering or missing when on the freeway going downhill on cruise control. Figured it was the engine trying to slow down the momentum going downhill, though it never used to be this rough when newer.

Today the check engine light was blinking as this was occurring, but went out once I released the cruise control.

Suggestions? Thanks.

 

[dnt1010]

I am going to guess cylinder #1 plug has lost part of its ceramic tip and is partially fouled. (Just a WAG LOL) Lets get that #1 plug pulled out and get a close up pic of it posted on here right away!

 

[wjburken]

After you pull #1, might as well pull the others. Also, get a scanner on it and see if you have any stored codes that might point you in a good direction.

 

[GreyStone]

sounds almost like an afm thing

 

[Camarochief]

when the light is flashing it is misfiring. plugs? wires?

 

[GreyStone]

could one of the Hybrid batteries be shot - another person on here mentioned they had to replace the traction battery on their Hybrid.

 

[Marc Marc]

Thanks for the suggestions. I am on a trip and won't return home to my tools for a couple of weeks. I will pull the plugs and probably change them when I return. Will let you know if that helps once I get the chance to get it done. Drove it the last two days with no issue or engine light coming on, but have been on level freeways.

 

[Marc Marc]

Replaced all plugs and wires. Engine is smoother and gas mileage is restored, but I still notice what feels like the cruise control is fighting (vehicle stuttering) when coasting downhill on the freeway. Otherwise all is well; no codes.

 

[OR VietVet]

Do you have a tow/haul mode on the transmission? If so, does it do it in both modes of tow/haul mode or without it on?

 

[Marc Marc]

Unlike my previous non-hybrid Yukon Denalis, there is no tow/haul mode on this model.