Question for the Mad Dr.

[RED4]

Originally Posted by orygunf150

Anyway, I notice a big reduction in power if I manually take off in 2nd or 1st.

As I said before, when you put your truck in 2nd gear it stays in that gear ALL the time.

So, if you are at a dead stop, put it in 2nd and then proceed to take off, you are starting in 2nd gear - which will feel like there is a reduction in "power" off the line.

[orygunf150]

Well I was hoping to hear from Bill on this one (I'm sure he is pretty busy) but there is a definate reduction in power. I monitored comm gear while taking off in 2nd gear, after a few seconds shifted to 3rd and it took off like a different truck. Didnt shift to 1st, nor did the tc ever lock. I wonder if it does it in 4WD?

[Jackpine]

Originally Posted by orygunf150

Well I was hoping to hear from Bill on this one (I'm sure he is pretty busy) but there is a definate reduction in power. I monitored comm gear while taking off in 2nd gear, after a few seconds shifted to 3rd and it took off like a different truck. Didnt shift to 1st, nor did the tc ever lock. I wonder if it does it in 4WD?

We're back from Sedona. Here's what I learned:

If I start my truck moving with the shifter in 2nd gear, that's the gear it stays in - period! No 1st gear at all.

I observed my torque converter lock up in 2nd, 3rd and 4th gears, depending on the load and speed. Once in a while, it would shift from 3rd with the torque converter locked directly to 4th without unlocking the torque converter and that would feel "harsh". With the speed control on, coming down a hill, as long as the torque converter stayed locked, I could feel engine braking, but if I tapped the brake to disengage the cruise control, the torque converter would also unlock and the feel of engine braking would disappear.

The TC would lock in 4WD, which I used on a few "unmaintained" roads for improved traction and control. But, now I have a VERY dirty truck!

- Jack

[SinCityFX4]

Good info thanks Jack

That sedona red dirt/mud is alomost worse than beach sand isn't it.:gag::whistle:

[Jackpine]

Originally Posted by SinCityFX4

Good info thanks Jack

That sedona red dirt/mud is alomost worse than beach sand isn't it.:gag::whistle:

The Sedona dirt is almost like red talcum powder! Super, super fine and all over everything. There was a very nice, steep, "sharp-rocked" road out of Sedona called Schnebly Hill Road that we drove up. Beautiful drive at about 5 -10 mph and a great test of tire durability. My understanding is that it was the original route in and out of Sedona. Doesn't look like much has been done to improve it since then.

Bill, I wonder if the reduced power in 2nd is just to minimize slippage on startup in snow or on ice? I do know though that it's a good gear to pull a trailer up a steep grade (7%+) in the mountains.

- Jack

[Power Hungry]

Originally Posted by orygunf150

Well I was hoping to hear from Bill on this one (I'm sure he is pretty busy) but there is a definate reduction in power. I monitored comm gear while taking off in 2nd gear, after a few seconds shifted to 3rd and it took off like a different truck. Didnt shift to 1st, nor did the tc ever lock. I wonder if it does it in 4WD?

For some reason, I've noticed that the truck will go into a reduced power mode in Manual 2nd Gear. I'm not sure what the purpose of this is other than to prevent burning up the clutches in the transmission by trying to start from a dead stop in 2nd gear. I've never really been concerned about it since this is not a normal driving situation for most folks.

By the way, you can manually recreate the symptoms. Put the truck in 2nd and take off from a stop. At about 30 MPH, matt the gas pedal and after a second or two shift from 2nd to Drive. You'll instantly feel a change in power output. Make sure you're not downshifting when you switch to Drive or it makes the whole test pointless.

[orygunf150]

Originally Posted by Power Hungry

For some reason, I've noticed that the truck will go into a reduced power mode in Manual 2nd Gear. I'm not sure what the purpose of this is other than to prevent burning up the clutches in the transmission by trying to start from a dead stop in 2nd gear. I've never really been concerned about it since this is not a normal driving situation for most folks.

By the way, you can manually recreate the symptoms. Put the truck in 2nd and take off from a stop. At about 30 MPH, matt the gas pedal and after a second or two shift from 2nd to Drive. You'll instantly feel a change in power output. Make sure you're not downshifting when you switch to Drive or it makes the whole test pointless.

Yes Bill, thats exactly what i'm talking about. Sometimes I drive in the mountains with some short but steep hills where I like to hold it in 2nd gear, but the power is just not there. I was wondering if it is an electronic thing that can be defeated with the programmer.

[Power Hungry]

I'm still looking at that. We know where the throttle tables are but for some reason it doesn't seem to work on the 2nd Gear settings. Fortunately, the Expy does the same thing and as soon as I have a little time I'll be fixing that.

[orygunf150]

1st and 2nd gear positions cause the PCM to remap the throttle
essentially the throttle gets cut in 1/2 by placing the shift lever into 1st or 2nd. the throttle then is more "sensitive" and you have better control of the wheels.
this is achieved because you now have full pedal travel to control only 50% of your normal throttle...so you don't inadvertently spin the tires by giving it too much gas
it's a little known feature to help you control low speed situations. like boat ramps, towing heavy loads, 4x4 offroad

This is a response from Tylus on the FTE forum regarding the same issue, if it is the pcm remapping the throttle I would think it could be programmed to not do it. Or, perhaps there is a microswitch somewhere that can be bypassed. What do you think Bill?

[Power Hungry]

That's exactly what it's doing and I do know where the map is. The problem is that when we change it to improve the range, it often (read that as nearly always) sets a Throttle Control DTC. That's what I'm trying to work around.