2013 6l80 Issues

[blakbird]

Not sure if correct section to post this

 

My 2013 silverado  6 speed auto (6l80) started downshifting hard/delayed in lower gears and makes my truck feel heavy when coming to a stop . Also makes a rattling sound sometimes  when cruising in higher gears (30-40 mph) with low throttle opening and goes away once I give it a little more throttle.  When it makes the rattling sound feels like something is not engaging and it goes back to normal as soon as I give a little more throttle. Under than that the shifting feels good.  What can it be ? torque converter?

[riverbanks]

Wondering if that's the flapper in the exhaust sticking closed?

[swathdiver]

4 hours ago, blakbird said:

Not sure if correct section to post this

 

My 2013 silverado  6 speed auto (6l80) started downshifting hard/delayed in lower gears and makes my truck feel heavy when coming to a stop . Also makes a rattling sound sometimes  when cruising in higher gears (30-40 mph) with low throttle opening and goes away once I give it a little more throttle.  When it makes the rattling sound feels like something is not engaging and it goes back to normal as soon as I give a little more throttle. Under than that the shifting feels good.  What can it be ? torque converter?

 

You definitely want to get this hooked up to the proper scan tool, like a Tech-2, so you observe what's going on inside and see if the transmission has thrown any codes.  If you join AllDataDIY, you can run through the troubleshooting guide with your symptoms.

[newdude]

5 hours ago, blakbird said:

Not sure if correct section to post this

 

My 2013 silverado  6 speed auto (6l80) started downshifting hard/delayed in lower gears and makes my truck feel heavy when coming to a stop . Also makes a rattling sound sometimes  when cruising in higher gears (30-40 mph) with low throttle opening and goes away once I give it a little more throttle.  When it makes the rattling sound feels like something is not engaging and it goes back to normal as soon as I give a little more throttle. Under than that the shifting feels good.  What can it be ? torque converter?

 

Any check engine lights?  Any pending codes or codes stored?  How long have you had the truck, and how many miles?

 

1 hour ago, riverbanks said:

Wondering if that's the flapper in the exhaust sticking closed?

 

OP has a 2013.  Flapper didn't get added until 2014 body style. 

[blakbird]

1 hour ago, newdude said:

 

Any check engine lights?  Any pending codes or codes stored?  How long have you had the truck, and how many miles?

 

 

OP has a 2013.  Flapper didn't get added until 2014 body style. 

It has about 86k miles. Have had it since 2014 with 30k miles. No TCM codes just got it scanned earlier . Not sure what to do now. My friend has a  matco maximus 3.0 not sure whatever diagnostics i can do

[blakbird]

Btw ive had this issue for about a year already