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Discussion Starter #1
I have a 2010 Traverse with 160,000 miles on it. Transmission has seemed fine its whole life. Lately I have been getting a shudder as you accelerate and hit RPM of 3,000. As soon as it downshifts it goes away. When going up a hill it will do this in any gear you are in at 3,000 RPM. While coasting it does not do this shudder at any RPM (so it is engine and/or Auto trans- not tires out of balance etc). I tried flushing the auto trans fluid 2X but no change. Does anyone know what is going on? Does it need new trans? The car is great otherwise but only worth ~2-3K $ so not sure what the most reasonable approach would be regarding sinking money in. Will the car run like this for 50K miles if I don't do anything or is it about to blow up? I don't know much about this area. thanks for any thoughts.
 

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It could be many different things, but it might be a misfire. I just replaced a bad coil pack on my '08 Grand Prix that had an almost identical issue. It would start misfiring around 2,800 rpm and get really bad as it was pushed harder. Then the transmission would shift, RPM's drop, and problem gone. Any engine may have an acceptable number of misfires on a trip. There needs to be a set number of misfires within a certain time frame to actually set the check engine light. If you have access to a scanner tool with diagnostics, you can check and see how many misfires you're getting. A handful in a 15 minute drive is not unusual, but a few hundred is a sign of an issue that won't likely meet the minimum to set the CEL. And if you have the tendency to back off and take it easy when the shuddering starts, you may never set that CEL and get a code. It's worth checking into since it's an easy and cheap repair compared to a tranny.

If you're not mechanically inclined, find a mechanic you can trust (that can be the hardest part) and tell them up front, you just want to pay the diagnostic fee to find out what's wrong and that you probably can't afford any repairs right now. I find they're more likely to be honest if they know up front they won't be making more money off of you. Keep in mind, that even the best mechanic can misdiagnose a problem though. But if it's misfiring, I'd expect they could identify that no problem.

When my last coil pack went on my way to work, I checked it by laying on the throttle when going up a grade on the highway. I never gave it a chance to shift and pushed toward wide-open throttle. That caused many more misfires and set the CEL. Once I got to work, I pulled out the cheap code reader I keep in the car (yes, it has lots of issues on a regular basis) and found the "random misfires" code. Using my fancy scan tool once home, I was able to see the 2 cylinders that had the misfires and identify the offending coil pack (1 pack per 2 cylinders). I'm new to the Traverse, but I believe there's a coil pack right on top of each spark plug.

Good luck.
 

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Discussion Starter #4
Case closed....the fix:
No engines misfires. I went to google and found people with other vehicles saying a cv joint going bad can make a vibration at a certain rpm so I decided to replace as a starting point (ignition coils was going to be my next try at fixing this). Went to NAPA and got 2 front CV joints for 85$ each. Putting the second one in on drivers side and when I pulled the old one the transmission fluid starting coming out (I knew that could happen but had jack stand on highest setting so couldn't be prevented). After axle, brake, wheel were all reinstalled I decided to just drain out the rest of the trans fluid and fill with new as long as vehicle was lifted. As I was laying there I saw the metal skid plate in the front underside had been dented by hitting a rock or something. I removed it and immediately saw a nice shiny spot on the rusty exhaust pipe and knew right away I had found the real culprit. So problem is gone and I have two new cv joints that I might not have needed but oh well.
 

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Case closed....the fix:
No engines misfires. I went to google and found people with other vehicles saying a cv joint going bad can make a vibration at a certain rpm so I decided to replace as a starting point (ignition coils was going to be my next try at fixing this). Went to NAPA and got 2 front CV joints for 85$ each. Putting the second one in on drivers side and when I pulled the old one the transmission fluid starting coming out (I knew that could happen but had jack stand on highest setting so couldn't be prevented). After axle, brake, wheel were all reinstalled I decided to just drain out the rest of the trans fluid and fill with new as long as vehicle was lifted. As I was laying there I saw the metal skid plate in the front underside had been dented by hitting a rock or something. I removed it and immediately saw a nice shiny spot on the rusty exhaust pipe and knew right away I had found the real culprit. So problem is gone and I have two new cv joints that I might not have needed but oh well.
so what was the issue? An how did you fix the issue.
 

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Discussion Starter #6
It was just the plate rubbing on exhaust. I took it off and hammered it flat.
 

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It was just the plate rubbing on exhaust. I took it off and hammered it flat.
Interesting. An exhaust pipe vibrating on the body or other parts can trigger your knock sensor, cause a false engine knock at a certain engine speeds. The false knock will reduce ignition timing to the bare minimum, reduce power, and cause a low droning sound from the engine and transmission.
 
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