Rough idle and bad shifting

[Baytrucker]

Hello,

 

I have a 2017 Sierra 1500, Double Cab, 6spd, V8 5.3.

 

My truck idles rough. My truck also shifts hard, especially on downshift.

 

Both of these symptoms are exacerbated significantly by having the air conditioner on.

 

The rough idle is intermittent and feels like a miss. It shakes so bad sometimes my coffee will splash out of the cup into the cup-holder. It is not consistent. It a shudder every 0.5 to 3 seconds. At warm idle, the RPM sits just below 500rpm. At park, the RPM bumps up to 600-650. The shudder can barely be felt in Park or Neutral, but is still noticeable if you are paying attention.

 

The hard shift is a clunk, mostly noticeable at lower gears (3-2 and 2-1) when downshifting. It becomes more pronounced on longer drives.

 

Like I said, both symptoms get 200-300% worse when the air conditioner is running and when the engine is warm.

 

The monkeys at the dealership say that this is normal and will not attempt diagnostics or a fix. There is no other dealership nearby.

 

I've tried cleaning the throttle body and the MAF sensor; they are pristine. I've run injector cleaner through my tank, and used higher octane good quality fuel. Oil changes every 5000km. None of this has made a difference. I am running a range unit to turn of AFM, but this device doesn't appear to effect the issue either way.

 

I noticed this barely and intermittently when I first bought the truck, but is is getting progressively worse to the point where its hard to ignore.

 

What else can I do here, or do I just have to live with it?

 

 

[JimCost2014]

8 hours ago, Baytrucker said:

Hello,

 

I have a 2017 Sierra 1500, Double Cab, 6spd, V8 5.3.

 

My truck idles rough. My truck also shifts hard, especially on downshift.

 

Both of these symptoms are exacerbated significantly by having the air conditioner on.

 

The rough idle is intermittent and feels like a miss. It shakes so bad sometimes my coffee will splash out of the cup into the cup-holder. It is not consistent. It a shudder every 0.5 to 3 seconds. At warm idle, the RPM sits just below 500rpm. At park, the RPM bumps up to 600-650. The shudder can barely be felt in Park or Neutral, but is still noticeable if you are paying attention.

 

The hard shift is a clunk, mostly noticeable at lower gears (3-2 and 2-1) when downshifting. It becomes more pronounced on longer drives.

 

Like I said, both symptoms get 200-300% worse when the air conditioner is running and when the engine is warm.

 

The monkeys at the dealership say that this is normal and will not attempt diagnostics or a fix. There is no other dealership nearby.

 

I've tried cleaning the throttle body and the MAF sensor; they are pristine. I've run injector cleaner through my tank, and used higher octane good quality fuel. Oil changes every 5000km. None of this has made a difference. I am running a range unit to turn of AFM, but this device doesn't appear to effect the issue either way.

 

I noticed this barely and intermittently when I first bought the truck, but is is getting progressively worse to the point where its hard to ignore.

 

What else can I do here, or do I just have to live with it?

 

 

Where are you at on the mileage?

 

If you are still within range for the bumper to bumper/drivetrain, open a claim with GM, let them know how the dealership is treating you, and be persistent to get the truck fixed. They will rattle some cages, and hopefully get some results for you.

[Baytrucker]

9 minutes ago, JimCost2014 said:

Where are you at on the mileage?

 

If you are still within range for the bumper to bumper/drivetrain, open a claim with GM, let them know how the dealership is treating you, and be persistent to get the truck fixed. They will rattle some cages, and hopefully get some results for you.

I'm only at 22000km, mostly city. I thought at first it might be carbon due to all the short trips I take with it, but everything I can pull apart (MAF, TB, etc) all look fairly clean.

 

I called GMC directly. They said they can't open a case without a dealer. The dealer says they can't do service without approval from GMC. They are pointing fingers at each other.

 

I've opened a case with CAMVAP to try and get something done. I hear it can be quite a process. I was hoping someone here might have some smaller things I can check in the mean time.

[Ford Guru]

My cousin has the same issue with her 2015 Silverado with a 4.3L and a 6L80E transmission.  I dropped the transmission pan. Changed all the solenoid membranes on the TEHCM and replaced the fluid and filter. I even replaced the manual detect plunger. Shifting is much improved. But she still gets the erratic idle and it clunks into 1st gear. But only sometimes. My synopsis is that it has something to do with the torque converter lockout. Unfortunately this part is out of stock with no timeframe on future availability. They are in a class action lawsuit over these ****** transmissions currently and all parts are being thrown at warranty claims. GM really built a terrible transmission. And they know it.