Can I disable the AWD?

[brissim]

Alan relayed from Andres
Normally the power split is 10% to the rear and 90% to the front and the Haldex system can reverse the split to 90-10. By removing the axle or taking out the fuse, you gain atleat 10% more power. On a 3.2 that is roughly 20-24 HP, or 20 lbs./tq and another 2-3 MPG. THat is worth a little bit of effort.

I'm sorry - but this sort of analysis is nonsense. While I understand that disabling the AWD may direct 10% more power to the front axle, aren't you loosing that 10% drive from the rear axle? Overall, how can you have a 10% increase in power and torque when you have the same engine up front? And how exactly does this mythical 10% increase in power and torque get translated into a 2-3MPG (ie 10-15%) improvement in fuel economy? At the end of the day by disengaging the AWD all you a saving is - I would expect - no more than a few percent in transmission losses. And unless you actually remove all the AWD equipment, you are still lugging around the same weight.

To the OP - if you want to get a feel for the fuel savings, spend a bit of time looking at some international Volvo websites where they offer several Volvo models with the same engine and transmission, in both FWD and AWD. As an example (and there probably are several others), in European markets the S60 & V60 D5s are offered with both FWD and AWD. From their technical data, the saving in average fuel usage is a grand total of around 3% (6.2 vs 6.4 l/100km). However this 3% saving of the FWD version comes with a 4% reduction in weight over the AWD version (1630kg vs 1700kg for the V60 D5). I would venture to suggest therefore that the majority of this 3% saving in fuel comes from the weight reduction, not the change from AWD to FWD.

Tony

[netpres1]

Alan relayed from Andres
Normally the power split is 10% to the rear and 90% to the front and the Haldex system can reverse the split to 90-10. By removing the axle or taking out the fuse, you gain atleat 10% more power. On a 3.2 that is roughly 20-24 HP, or 20 lbs./tq and another 2-3 MPG. THat is worth a little bit of effort.

The claim of gaining 10% power is is not true. The engine generates the same power no matter how it is distributed.
If disabling the Haldex sent all power to the front wheels, you still have to move the same mass of vehicle with the same engine.

To save fuel would require saving the energy involved in moving the rotating mass and friction of the rear drive train assembly.
Even disconnecting the tail shaft wouldn't help as the mass would still be rotated by the rear wheels as you drive along.
To gain any significant benefit you would need to disengage the rear wheels at the hub so they could freewheel.

The Haldex used is probably a GenIII unit in your 2009 XC.
These are quite efficient anyway. I would guess that you might gain 1 - 3 % if you did it but would be interested to know
what happens in the real world.

David

[ingemar Carlsson]

David thank you for that reply! Any difference for my 010 3.2? How about my attempt to smuggle in and retrofit a d5?

[DennisM]

It seems to me that, pulling the fuse would only 'de-power' the AWD, not disengage it. Instead of power being sent there and the drivetrain working in harmony, it would just become induced drag.

With older 4wds, like in trucks, you throw a handle and it disengages the hubs and transfer case sending input to the front drive shaft. With the Volvo AWD system, pulling the fuse wouldn't disengage the mechanics of the drive system would it? It seems that this would just tell the controller to not send power there. I'd be surprised if it didn't help, but would not be surprised if there was a drop in mileage. Meh. I don't really know the 'magic' of the Volvo system, so I'm just theorizin'.

Sounds like an interesting test. Post your results!

[Cattrick]

Some functions of the DTSC will never be disengaged, which would be undesired in many driving situation anyway.

I have tried just to disengage DTSC electronically just too see if I can feel anything different, think I noticed gear changing being more smooth. But can't say anything for its scientific correctness though

[kr8m8pr8]

Sorry, this is 5 years late. Pulling the fuse from the back to disable the AWD module reduces fuel consumption significantly. I keep the fuse out when driving on plains and on the highway so I can get 2km more per liter. There should have been a switch in the front. The drawback I think is anti skid switching off, front tires being used more, reduced stability, roadability. Plus you cannot get up to the places where you bought this vehicle for, like uphill in snow or mud.

[netpres1]

Interesting.

Do you have the figures that you can post.
Can you also let us knwo if you have petrol or diesel and also what year.