Hi guys,

I have been lurking here for a while since buying my Grand Voyager. It's a 2006 model 140000 miles on the clock with the 2.8 diesel engine. You have already given me a great deal of advice, through these threads, saving me a few pennies :-) .

Anyway. My question is this - When driving along doing a constant speed. When I push the throttle to increase the speed, the rev counter goes up sharply, with no noticeable increase in speed. The speed will gradually catch up with the rev counter, almost as if it is a slipping clutch on a manual box.

Should this happen?

Thanks

Fraser

 

When you put your foot down past a certain point on the accelerator the gearbox automatically kicks down into a lower cog therefore the revs shoot up while maintaining the same speed.
The 2.8d isn't exactly "a ball of fire" and may take a while to accelerate.

 

Thanks for your response.

It's not the kickdown, say cruising at 2000rpm. Push throttle, revs go up to 2700rpm within a couple of seconds. Speedo does not move initially, then slowly increases.

Cheers

Fraser

 

Fraser, I have the same year, model and type of GV to yours. The behavior of your GV in your last message is not quite the same as mine, but it will depend on whether you're on the straight or up an incline. This autobox is maybe a little old-fashioned in its operation compared to the ZF autobox in my Jag. This is not necessarily a bad thing.
Nowadays, all torque converters have a wet-clutch around them controlled by the micro. If the Chrysler programmer let the torque-converter operate for longer before the TC clutch comes into play, you will get a 'buzz' in the revs before the TC transmits the power. The clutch comes into play here at this time to save a little fuel, and as it's a wet-clutch, wear is not really a problem when it's used in the slipping mode. It also depends on the engine power available. The GV diesel makes 150horse, my Jag. made 210horse on less vehicle dead-weaight, so I suppose this would maybe explain why you have a rev. jump for a second or two. The Jag/ZF was also a "learning" autobox, and would sense the driver's habits and select an appropriate shifting program from the store. I don't think the GV. does this.
As for practical aspect, if the ATF fluid hasn't been changed in a long time, it should be.
In normal driving, the additives in the ATF fluid will wear out in 30,000mile for mineral, and 60,000mile for proper synthetic. (PAO). There is a specific additive for the TC clutch, mainly to control any clutch-judder (or shudder as americans call it).
I mentioned "save a little fuel" and in this context, I don't think the Chrysler design has deceleration fuel shut-off. The TC clutch is used to keep the engine turning on the over-run principle with fuel shut off down to about 20mph., whereupon the fuel is allowed again to the engine. I've discovered with the GV engine, coasting in neutral will save a measurable amount of fuel in city traffic, (a la' hypermiler), thusly making me think there is no deceleration fuel shut-off in operation here. But someone may have better information on this one.

Leedsman.