Rough Idle

[BWood]

I have a 2012 Tahoe that idles very rough at times. When sitting at a stop light the truck shakes. The tach will drop and come back up. It seems a lot worse when the AC is on. I took it to the dealership and they found a bad spark plug and changed it. The idle got better but is still not right.

I took the truck back to the dealership to have them look at it again and they said they could not recreate the problem and that there aren't any codes saying that it ever missed. I was told to bring it back in if it was happening and they would check it out. It happens almost every day. Today it was especially bad so I drove it to the dealership. They sent a tech out to look at it. They didn't even ask me any questions. I had to chase the guy down to try to explain what it was doing. He hooked it up to his computer and came back and told me there wasn't anything wrong and that those 5.3s just run that way.

The service rep came out to talk to me and the only thing they said was that there isn't anything wrong but I could pay for a fuel system cleaning and see if that would help. When I suggested that I take it to a different dealer she told me I should do that.

I've been in other Tahoes and Suburbans and have not had this issue. My 2004 Tahoe ran much better than this 2012.

So, any idea of what could be my issue? Should I try to take it to another dealer? Do other Tahoes run rough like this? I'm at a total loss of what to do. I really like my truck and the new Tahoes but if they are all built like this one is I'll never buy another one! I will definitely not be going back to the same dealer ever again!

 

[MO Viet Vet]

Well if it got a little better with one spark plug then I would replace all of them to make them all the same age. How many miles on the plugs? Sounds like also your problem is intermittent. If it does not throw a code and is not having the problem in front of a dealer tech then they don't want to go further till you agree for more money. I would get some MAF sensor cleaner at the parts store and clean the MAF. Sounds like an idle problem when under a load, like when the a/c is on.

 

[BWood]

The car has 40,000 miles on it. I'm going to do all new spark plugs next weekend can clean the MAS and see if that helps. It seems pathetic to me that the dealership didn't change all of the plugs when they found the bad one. To make it worse they told me that they found the bad one and replaced it but they realized the replacement was bad so they had to replace that one. The plugs they are using must be total garbage.

Now I'm going to be out money for stuff that should have been tied to the original claim. Thanks a lot Chevy and Leman's Chevy City.

 

[MO Viet Vet]

The odds of having a bad plug and then replacing it and again having a bad plug are very low. The tech may have damaged the new plug when installing it and then caught it after the restart. I would be worried that the plug wires could have a problem, also. The reason all plugs were not changed is because under warranty they only change the bad one and not a complete set. It is the nature of the warranty beast.

 

[xxChevyxx]

Maybe a bad O2 sensor?

 

[fjmichaels]

X2 on the O2 sensors. If you're getting a misfire, then your SES should be flashing. If the car runs rough after starting then gets better as it warms up, then it's most likely a bad or damaged O2 sensor. Make sure that if you decide to changeout the O2s, that you use OEM sensors and not aftermarket.