4x4 Low Question

P71_CrownVic · February 25, 2009

One thing I hate about being a nOOb is the vast number of questions I have. I have been searching a lot which has answered a ton of my questions, but sometimes, I just cannot find the answer I am looking for. This is one of those times.

Now, for the record, the only other vehicle I have used 4X4 low in, is my Grandma's old 1996 Explorer...when we needed to pull the boat hoist to shore in the fall. I distinctly remember that 4X4 low was a torque monster, with even a very light throttle application enough to put you back in the seat.

Anyway, on my "new to me" Silverado, I am not sure if 4lo is working correctly but differently than I am used to, or if something is wrong. Whenever I put it into 4lo, it goes in just fine, but I never get that "jumpy-ness" I am used to. I will say that when I put it into gear (D), it does jump as the trans engages, but when I push the gas it feels very lethargic...almost like the truck is starting in a higher gear. Now, I know that the truck is NOT in a higher gear...I have only had it in drive...but it feels similar to that.

I have read about 'torque management'. I understand the basic premise (to manage torque... ), but could somebody elaborate on how the system works and if that is somehow involved?

The truck is still under warranty, so I am not concerned if something is actually wrong, but I would rather have you guys tell me it is working properly than to go to the dealer and look like a fool.

pj5454302 · February 25, 2009

the lack of jummpyness might be due to the fact that your truck has eletronic throttle. On older trucks with the actul throttle cable it is jumppy. Like my truck when i put it in 4lo i can just let the clutch out and idle along with out touching the gas

bill190 · February 25, 2009

The way I know my 4 low is working (different truck) is by driving in mud slowly (which we have plenty of around here this time of year). In 2 wheel drive, the truck does not want to go anywhere or the front will slide to the left/right. In 4 low, it will go forward/backward easily and head where I am aiming!

As to asking the dealer how the truck should work, my experience is that I get all sorts of different answers depending on who I ask. If you can get a VIN printout of the specific transmission/differentials you have, then the parts/service guys can usually give you fairly accurate answers if they have time.

I've had no luck reading the owners manual. Does not explain technical details on how things work. The best method I have found was to get the factory service manual set and look up my specific drive line options and read the descriptions on how they operate. So for me the "Instruction Manual" is the service manual set.

And for my model of truck, there are all sorts of transmissions and differentials available - so depending on what you have, things will operate differently.

MarkD · February 25, 2009

I know that in 4 lo my truck is QUITE responsive. Kindof like someone that cant drive a car with a manual transmission.

Try putting your trans in 1st gear while in 4lo.

P71_CrownVic · February 25, 2009

I know that in 4 lo my truck is QUITE responsive. Kind of like someone that cant drive a car with a manual transmission.

Exactly. That is how I imagined it would feel like. The truck revs like it is in 4lo, but I don't get the responsiveness.

Try putting your trans in 1st gear while in 4lo.

I'll give it a shot!

Sir Dan · February 25, 2009

I'm pretty sure that when these newer trucks with electronic throttles are put into 4Lo, the engine computer follows a different fueling map that slows down throttle response and limits RPM. My guess is they did this to try and limit damage to the drivetrain from abuse, also because they don't make the drive train components as robust these days to save money.

gvbhunt · February 26, 2009

When you put your truck in 4-low you are multiplying the engines torque by a factor of 2.7 so the computer pulls timing and uses other methods to keep it from destroying itself (or GM from having to warranty anything). Dont worry, the power is still there. Put it in 4-low and wrap a chain around your house, I bet you can still pull it off of its foundation.

svensk · February 26, 2009

I know that in 4 lo my truck is QUITE responsive. Kindof like someone that cant drive a car with a manual transmission.

Yeah, your's is a drive by cable as well just like mine. I think 4-low on any 2004+ truck acts different again because of the drive by wire response.

VMax2007 · February 27, 2009

I know that in 4 lo my truck is QUITE responsive. Kindof like someone that cant drive a car with a manual transmission.

Yeah, your's is a drive by cable as well just like mine. I think 4-low on any 2003+ truck acts different again because of the drive by wire response.

Fixed.

P71_CrownVic · March 3, 2009

Update:

Just in case anyone has this same question in the future, I thought I would post what I discovered.

I decided the other day to take my running boards off. To do so, I put my truck up on ramps using 4X4 low. Long story short, it worked just fine. It crawled up those ramps like they weren't there. So, everything works just like it's supposed to.