Transmission downshifts 2010 Equinox

jpapu said:

Just picked up my wife’s new 2010 Equinox from the dealer and went for a drive. As I was driving I notice that if I build up speed and take my foot off the gas the transmission will downshift, as a result the tachometer RPMs jump up. None of the cars I have owned over the years have done this. I don’t believe this is good as higher RPMs = lower gas mileage. Has anybody else notice this and reported it to the dealer? If yes what was the outcome?

Click to expand...

Direct injection engines have a very agressive DFCO (deacceleration fuel cut-off)....The surge in RPMS is not effecting your gas mileage being the the injectors are disabled. The engine will downshift, and coast down having the injectors turned off. Instead of dropping quickly to "idle" speed the engine/tranny (with assistance from the PCM) is trying to keep the rpms up, while having the injectors turned off (no fuel), thus giving you improved MPG's around town. As long as the rpms are above idle speed, during deaccelerations your injectors are turned off. This was changed with the reprogram flash that GM was doing on the 2.4's, they where making it less noticeable/aggressive IIRC.

But if you watched your factory wb sensor (our 02 sensors are wideband sensors) you could see up to 65:1 AFR's during this. Maybe I'll log it if I remember to take the laptop around for a drive.

It is helping emissions and saving gas....Just feels like drag when driving, but its in all DI engines in some fashion