Rpm drop when stopping.

[Doubeleive]

@NickTransmissions any idea's? could it be something in the transmission, tc lockup, etc
this should be the 4l60

 

[Dustin Jackson]

6l80e?

 

[NickTransmissions]

@NickTransmissions any idea's? could it be something in the transmission, tc lockup, etc
this should be the 4l60

Could possibly be TCC dragging a bit but he mentioned having a Dorman throttle body installed and ordering an OEM one..I'd await to see the results of the swap there as I bet that fixes the problem..Dorman makes garbage for the most part...

 

[Doubeleive]

Could possibly be TCC dragging a bit but he mentioned having a Dorman throttle body installed and ordering an OEM one..I'd await to see the results of the swap there as I bet that fixes the problem..Dorman makes garbage for the most part...

he also stated he tried his friends TB and same results, also had the Idle bumped up and same result.
would the tuner be able to TC status on a drive test?

 

[mattbta]

What are your volts doing when the RPM drops?

 

[NickTransmissions]

he also stated he tried his friends TB and same results, also had the Idle bumped up and same result.
would the tuner be able to TC status on a drive test?

Thanks for the additional info - I didn't see those comments, just looked at the previous page.

Yes, you can monitor TC and all transmission control parameters via HP Tuners to see what's going on at any given point in time and tell if the TC is being commanded on when it shouldn't and vise versa. That said, TCC dragging usually doesn't last long before it completely fails and you stall out when coming to a stop (assuming it's stock on/applied) or the TCC lock up solenoid has malfunctioned...Additionally, you usually store P1870 or similar DTCs if this is happening for more than two consecutive drive cycles with no code resets.

Ok, bumped the idle from the factory 550 in gear, and 500 in park or nuetral up 50rpms on both. So rpms are still dropping down to 350 when braking, and now its starting to do it even at low speeds, but i think its the temperatures causing it. When it was cooler out it only did it on medium to hard braking. It did make it a little peppier off the line, so will keep the new settings, or do you guys recommend setting it to 650, which seems alot.

Have you put a vacuum gauge on the engine at idle? Looks like you replaced and/or checked quite a few things (just read your first post)...

Also, do you have a 6L80 (six speed)? Those converters are much more failure prone than the TMBX converters that went with the 4L60Es.

 

[Hodgeee]

Ok, datalogged the driving. Engine load at idle in gear and braking is 23% to 25%, regardless of braking force, which is normal for these tahoes. This means nothing with the tranny, and no extra drag from pullies, even AC on and off was only maybe 2% more drag.

My tuner only allows 50rpm increase increments. But it showed base idle values at 600rpm idle in park, and 500rpm idle in drive. So i bumped it to 600 and returned the park idle to 600.

Now braking it only drops to 450rpm, and 400 when hard braking. This is much more acceptable and didnt feel like it was shaking that much or surging when it dipped. Plus off the line in summer in Vegas makes it feel more like a Power Wheels, than a truck. It takes off nicely now if i need it to. Im gonna just give up at this point. It drives much nicer, i can live with it.

If there is any change with the new TB, ill post, but not expecting anything.

Thanks for helping all, it did give me routes to take that escapped me.

 

[Hodgeee]

Oh, by the way no voltage drops or spikes.

 

[NickTransmissions]

Ok, datalogged the driving. Engine load at idle in gear and braking is 23% to 25%, regardless of braking force, which is normal for these tahoes. This means nothing with the tranny, and no extra drag from pullies, even AC on and off was only maybe 2% more drag.

My tuner only allows 50rpm increase increments. But it showed base idle values at 600rpm idle in park, and 500rpm idle in drive. So i bumped it to 600 and returned the park idle to 600.

Now braking it only drops to 450rpm, and 400 when hard braking. This is much more acceptable and didnt feel like it was shaking that much or surging when it dipped. Plus off the line in summer in Vegas makes it feel more like a Power Wheels, than a truck. It takes off nicely now if i need it to. Im gonna just give up at this point. It drives much nicer, i can live with it.

If there is any change with the new TB, ill post, but not expecting anything.

Thanks for helping all, it did give me routes to take that escapped me.

Didnt realize you were in Vegas - so am I....PM me if you need any help and we can take a look at it together at some point

 

[Hodgeee]

May consider especially if you have a full active scanning pad. My handheld tuner can datalog and then i look at it in Data Viewer. But i cant look at the pedal control values, or mid TB values properly, only going over driven data, same for MAFS.