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2 issues knocking noise and loud pop noise too~

8K views 4 replies 5 participants last post by  petevw 
#1 ·
I have an 2007 Envoy Denali purchased in February of 2007.
** ISSUE #1-- No real problems with it but did start to notice after a while as I am riding down the road if I let off of the gas for a second (ex. someone turning in front of me) and then put back to the gas again to accel. the engine makes a knocking noise. I relate the noise to a straight drive not put in too high of a gear and the knocking noise the engine would make. I have put better gas in it as well as octane booster and it is still making the same noise.
**ISSUE #2-- We got in to the Envoy one nite leaving a party and as the engine was started and we were still sitting there had not put it in gear or anything there was this loud pop-- it sounded like someone had ran into the back of the car to the point that I turned around to see what it was. Nothing had it us and we both had no idea what it was. The next morning leaving a store started the engine put into rev. and the same noise again! This does not happen all of the time is very random-- not just sitting, not just on cold weather or anything like that. Has happened not in gear, just put in rev. and also going down the road-- just last week it did it on the interstate and again I looked back to see if I had been hit. The more I hear the noise it sounds like it is coming from the front right tire area mostly and at times poss. the rear right tire area but, mostly the front right. The GMC place said they could not find anything that I could leave it there for a while and drive the nasty rental but I could not take it esp during the holidays. Please give me some help here!!!:confused:
 
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#2 ·
The only thing I can think of is you have the Denali and it has the ride leveling suspension or airbags i guess. That could be making the popping sound.
Maybe on the letting off and accelerating issue, sounds to be some slack in the drive train. Maybe in the tail of the transmission or the ring and pinion gears in the diff.
I am no mechanic though so I could be wrong
 
#3 ·
i also thought about the slack in the driveshaft- as you let off gas, then step on it, theres that little lag where you then feel the engagement of the internals.....
I usually feel something like that when decelerating, you can feel that little pop as it goes thru its downshifts...

also- thought about your rear air suspension....
 
#4 ·
Sorry for the late reply sumerl, I just took my 07 Denali in for the same complaint ISSUE #2 and they told me it was the belt tensioner and that a lot of them do it. They didn’t offer any fix. I also complained of a slight whine from the rear differential, they took it for a drive and said it wasn’t bad enough to fix. I know there is a service bulletin on the rear differential noise but I haven’t read it. I think I will try a different dealer.
 
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