Lack of engine braking on Omega Auto - BodgeJob
Does anyone know if the auto box on a 2.5 V6 Omega is supposed to down shift on a closed throttle (i.e. going downhill foot off accelerator)? I thought it used to do this (occasionally) but have noticed recently that it tends to roll on downhill and on the level without any appreciable retardation. I have had the inlet manifold off to do the rocker cover gasket and it seems to have occurred since then. Is downshifting triggered by the vacuum in the inlet manifold which may be suffering a leak?

Many thanks

Jon
Lack of engine braking on Omega Auto - Mark (RLBS)
Mine doesn't, don't think it ever has. (shift down under engine braking, I mean).

M.
Lack of engine braking on Omega Auto - Dave N
Some will re-lock the torque convertor after a period of deceleration from top gear.
Lack of engine braking on Omega Auto - Dynamic Dave
My previous auto Cavalier didn\'t, my current auto Vectra doesn\'t, and my Dad\'s auto Astra doesn\'t. When I want to use the gearbox to engine brake I press the Sport button, then knock it off again shortly afterwards. This drops the gearbox down from 4th gear to 3rd. It also helps with the fuel economy and less brake wear as well. If travelling down a steeper incline I sometimes move the gearstick from Drive to 3rd, then 2nd gear.
Lack of engine braking on Omega Auto - BodgeJob
Thanks for the comments. It is reassuring to know that it is not just my car, or more importantly that I have not solved one problem only to cause another. It may of course be ticking over slightly faster which has the same effect of not slowing the car down so noticably. I guess this too could be down to an air leak on the induction side?

Rgds Jon
Lack of engine braking on Omega Auto - JonM
The autobox on my 3.0 Omega (facelift model) claims to have adaptive shift patterns. One thing it does is change down to third when it detects the car going down a reasonably steep hill on the overrun. I've no idea how it all works though.

Cheers - Jon
 

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