Ping/Chatter over 60 mph

[LM7Yukon]

I get a ping type noise over 60mph while coasting or accelerating very lightly. I tried different fuels, and octane, and still hasn't got better. I now 5,000 miles, but it happened from 1000 miles on the odo, when the Yukon was only a week old. Its now 5 weeks, and the dealers can't figure out problem.

[GM-Tech]

Doesn't sound likely at all that it would be detonation (ping, knock, whatever you want to call it) if it occurs while coasting.

 

The only detonation I ever heard occur when one wasn't accelerating is on an engine that is badly overheated.

[LM7Yukon]

Doesn't sound likely at all that it would be detonation (ping, knock, whatever you want to call it) if it occurs while coasting.

 

The only detonation I ever heard occur when one wasn't accelerating is on an engine that is badly overheated.

 

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what can it be? It sounds terible, and happens accelerating or coasting but only over 60mph. Also, it started after they installed the factory aux tranny cooler, as it didn't come with it from factory.

[GM-Tech]

No idea what it could be. Noises are hard enough to find when one can hear them. Trying to diagnose one over the internet is nearly impossible.

[LM7Yukon]

No idea what it could be.  Noises are hard enough to find when one can hear them. Trying to diagnose one over the internet is nearly impossible.

 

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So what do you suggest short of filing under the lemon law. Is there a dealer here in NY, NJ or PA that you could reccomend? It appears to be mechanical. yet the dealers seem to only know what their computer tell them when they plug into vehicle.

 

Also, what does NC7 Federal emissions override mean?

[GM-Tech]

Call GMC and express your concerns. They'll probably have you go to another dealer if the one you're going to can't fix it. I don't know dealers in other parts of the country so can't recommend anyone.

 

I don't know what the lemon law is in your state, and that's between you and the manufacturer, the dealer has nothing to do with it.

 

As for the federal emissions override... I'm not sure. If you're in NY, I believe they have the same emission requirements on vehicles as California, so you would have a different emission system rather than the standard federal system.

[LM7Yukon]

Call GMC and express your concerns.  They'll probably have you go to another dealer if the one you're going to can't fix it.  I don't know dealers in other parts of the country so can't recommend anyone.

 

I don't know what the lemon law is in your state, and that's between you and the manufacturer, the dealer has nothing to do with it. 

 

As for the federal emissions override... I'm not sure.  If you're in NY, I believe they have the same emission requirements on vehicles as California, so you would have a different emission system rather than the standard federal system.

 

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I am in contact with GM, and so far 3 dealers aknowledged problem, yet none know what is causing it.

 

Regarding the emissions, it has both NE1 which is same as Calif, and then NC7 emissions override. Does that mean it cancels the Calif back to FE9 Federal? The enjine group family for all 3 levels are still the same, weather it be calif or Federal. Why the labels then, unless something really is different mechanically.

[GM-Tech]

Regarding the emissions, it has both NE1 which is same as Calif, and then NC7 emissions override.  Does that mean it cancels the Calif back to FE9 Federal? 

 

I have no idea. We only deal with federal emissions down here in S. Florida and even then we have no emission testing, so the only thing emissions means to us is that when there's a failure in it, it turns the SES light on.

 

I have no need or desire to figure out what all the various emission certifications mean so I really can't help you.

[LM7Yukon]

Regarding the emissions, it has both NE1 which is same as Calif, and then NC7 emissions override.  Does that mean it cancels the Calif back to FE9 Federal? 

 

I have no idea. We only deal with federal emissions down here in S. Florida and even then we have no emission testing, so the only thing emissions means to us is that when there's a failure in it, it turns the SES light on.

 

I have no need or desire to figure out what all the various emission certifications mean so I really can't help you.

 

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What emission equipment does the Federal have in a 2005 Yukon with the LM7 5.3 motor? Per the veci sticker under the hood, what engine family number does it conform to?