Haven't seen all those details....but every day I find something new.

The front bumper lower lip, is huge on the 2009, the 2010 is thin, given a higher stance look.

You can almost back up in auto-stop as you go forward in this mode, until you climb to the garage and engine starts !

The AFM (active fuel management) seems more jumpy so to say....willing to go 4V mode in every little chance it got !

On my 09 I have to search it

Still wish the '10 firmware to be uploaded to the '09, but still have no confirmation whatsoever.....at least in the "like hitting the rev limiter at launch or passing" issue !

 

Is Firmware GM's name for computer software or is this an actual component change in the computer system?

 

Guss, Baro=Barometric Pressure sensor, Airbox= filter element chamber (what Ken swapped out for the Volant unit.

Ken, Firmware is not a GM term, more like a generic software upgrade term that a lot of folks use, and doesn't refer to an actual hardware/chip/component change. GM has software series.

 

Thanks kc,
what is the barometric sensor used for exactly?

 

Rob thanks for the information. Guss I believe the Barosensor is for altitude compensation to adjust the fuel air ratio for combustion.

 

Thanks ken

 

My 2008 Yukon Hybrid used to switch modes too smoothly too notice. It was amazing. Gas mileage was 21 city and 23 freeway.

As parts wore out, switching became rough. The engine would rev unexpectedly. The first time it was the oil pump. The dealer replaced it under warranty and fixed the problem.

10K miles later the Yukon started clunking hard during some accelerations from full stop. I wasn't able to duplicate it at the dealer. The mechanic suspected a bad clutch between the hybrid modes and replaced it. At the same time he applied the transmission recall. It was firmware and a piece of hardware. This didn't seem to fix this rare problem.

Even worse, in the month since then gas mileage has dropped. When travelling a steady 30 mph, switching is smooth only half the time. The other times the engine revs both when switching off the gas engine and when restarting it. Gas mileage has plummeted to around 18.

Have any of you seen similar degradations? What ended up being the problem?

 

Evan,

Ok, so you've had an aux pump replaced, and then a clutch pack. If I could ask a few questions:

Which Clutch did the dealer replace? Is there any description on your invoice? Was any diagnostic trouble code listed as justification for the repair? It wasn't clear from your note, but it sounds like the launch clunk is still there?

Do you have any transients at highway speeds, or lower highway mileage, or is it just city driving where things are awry?

What is your vehicle mileage, and what was it when the launch clunking started?

Also, right around 28-30 mph the transmission may 'hunt' between EVT Modes 1 and 2 (not talking about V4-V8 here), and there is typically an rpm flair as the hybrid controller keeps all the speeds balanced. However, the degrading fuel economy sounds like a clutch is still slipping, or some other form of increased drag in the trans.

 

32,000KMs and NO DEGRIDATION in the Vehicle at all