Sluggish response in low RPM's

[kevshoe]

Back story: Have a 2011 LT with 130,000. Original owner. Was having a rough idle so last year did a tune up (wires/plugs) and found I had a broken motor mount (fixed). Earlier this summer, the tranny started making noises. Ended up taking it to a buddies transmission shop and they rebuilt it (about 2 months ago). Last Saturday, this sluggish issue started. When you take off, it feels like something is holding it back. Doesn't feel like the transmission is slipping, it just won't go. Once you get it in the higher RPM's, it runs fine. No codes thrown. Took it back to my buddy and he doesn't think it's the tranny. His comment was those things are finicky and will throw codes. I took off the throttle body, cleaned it and put on a new throttle position sensor (had it from back last year but never put it on...thinking it would help with the rough idle). Cleaned the MAF. All in all, it's running pretty dang good. Idle is still a little rough but that may be just the way it is (I'm comparing it to my 2005 Tahoe which is very smooth). Tranny had been running fine as well. We had only been driving it around town but last week my wife did take it on a 600 mile trip (300 both ways). No issues but that's the furthest it has gone since the tranny rebuild.

Not sure where I go from here. Any suggestions would be appreciated.

 

[Doubeleive]

you could try a fuel injection service or just throw in a couple bottles of injector cleaner over the next several tank fulls and see if the rough idle goes way, if you get a fuel injection service done typically it runs about $80 and they connect cleaner directly to the fuel rail with a tool so it's a much faster process.

 

[kevshoe]

Do you think that may be the sluggish response issue too? That is my bigger concern right now. It's borderline dangerous to even pull out into traffic because it just doesn't go...

 

[swathdiver]

Back story: Have a 2011 LT with 130,000. Original owner. Was having a rough idle so last year did a tune up (wires/plugs) and found I had a broken motor mount (fixed). Earlier this summer, the tranny started making noises. Ended up taking it to a buddies transmission shop and they rebuilt it (about 2 months ago). Last Saturday, this sluggish issue started. When you take off, it feels like something is holding it back. Doesn't feel like the transmission is slipping, it just won't go. Once you get it in the higher RPM's, it runs fine. No codes thrown. Took it back to my buddy and he doesn't think it's the tranny. His comment was those things are finicky and will throw codes. I took off the throttle body, cleaned it and put on a new throttle position sensor (had it from back last year but never put it on...thinking it would help with the rough idle). Cleaned the MAF. All in all, it's running pretty dang good. Idle is still a little rough but that may be just the way it is (I'm comparing it to my 2005 Tahoe which is very smooth). Tranny had been running fine as well. We had only been driving it around town but last week my wife did take it on a 600 mile trip (300 both ways). No issues but that's the furthest it has gone since the tranny rebuild.

Not sure where I go from here. Any suggestions would be appreciated.

This could be a transmission pump or torque converter issue. This can only be determined with a good scan tool that can see what's going on inside the system though. Of course, there are some other things with the engine and fuel system that could make it act that way too. The Tech-2 is your friend.

 

[Kraig]

Is it the same type of sluggish if you manually shift the tranny down to a lower gear before taking off? I wonder if it’s not starting out in 1st.

 

[kevshoe]

I also noticed that driving it around town the other day (while I was trying to trouble shoot this), the transmission temperature got up to 214F. Not towing a thing. That seems really high to me. I spoke to my buddy and ultimately he's going to throw a new transmission in it. Dropped it off today so hopefully get it back in a couple of days.

 

[donjetman]

the transmission temperature got up to 214F. Not towing a thing. That seems really high to me. I spoke to my buddy and ultimately he's going to throw a new transmission in it. Dropped it off today so hopefully get it back in a couple of days.

That's NOT hot. That's normal operating temp here in TX this time of yr. It's just getting hot enough to boil the condensation out. Dexron VI is good to a least 260 f.

 

[swathdiver]

Is it the same type of sluggish if you manually shift the tranny down to a lower gear before taking off? I wonder if it’s not starting out in 1st.

If you manually put the trans selector in 2nd, she will start out in 2nd gear. As for the temperature, where do you live, what was the temp outside and how were you driving? Does it have the K5L option code?

Transmission problems are usually one thing or two and rarely does the entire thing NEED to be rebuilt. But it's treated as such a mysterious piece of equipment AND the expense of R&R, folks are easily swayed into an entire rebuild.

 

[SnowDrifter]

Lets differentiate for a sec between engine and trans

What does it do if you rev it in neutral or park? Any codes? Can ya get a vid?

 

[swathdiver]

Lets differentiate for a sec between engine and trans

What does it do if you rev it in neutral or park? Any codes? Can ya get a vid?

It's already at the shop, too late to diagnose it.