Drivetrain, driving RPMs question

When driving on cruise control 60 mph if I run into any incline the truck will drop into overdrive into high rpms and then return to over drive rpms. ANY type of incline. Didn't notice it before the lift 3 in OME, bigger tires 285s 70, Steel front bumper TAG and home made (heavy) step bars. Is it just the strain of the power train from all the weight and lift or is there a solution to the problem.

 

outta overdrive

 

You added more weight and larger, more aggressive tires, for both more weight and higher rolling resistance. And the larger tires essentially changed your gearing to a higher ratio (lower, numerically). Your truck is working harder because of these factors, so it's downshifting. Really the only way to 'fix' it is to regear to a higher numeric ratio so that the truck isn't working as hard.

 

Normal.

As mentioned above you added weight, bigger tires, and changed your gear ratio. Only solutions are to regear and or add horsepower.

 

I thought I would have to do that (re gear). So when you regear how bad are you effecting mgs./the trucks performance. Is it honestly as easy as changing the gears in the rear end or is there reprogramming of the transmission needed. I mean I'm not a mall crawler but I'm also not a rock climber or off roader either. I use it as a truck when I need to.

 

Other than super charging it what other adding HP options do I have.

 

you will have better performance, mpgs will likely remain unaffected... while its easier for the motor to move the truck, it would be spinning faster at the same speed so its a wash.

If you are 4x4 you need to do both front and rear diffs. No reprogramming needed.


Supercharger is your only legit HP adder..... "cold air intakes" etc wont help.

About the only other thing would be something like the XTP intake MANIFOLD spacer. I caped MANIFOLD as it is NOT the same as a throttle body spacer.

 

^^^

This. Beat me to it.

 

None really.

I did Long Tube Headers and gained 16HP. Cost of about $700.

 

Ouch

 

Thank you, I am going to look into regearing front and rear diffs. Any suggestion on ratio and brand name

 

The cruise control has always been a bit touchy. It's trying to keep the exact same speed on flat ground as it is on an incline. It is always going to down shift. I always see this complaint on this forum but this is how cruise control works.

As a test: keep the pedal depressed to 1800rpm and hit the same hill. Your speed will slow down. Your natural reaction is to give it more gas, yes?

That's the same thing the cruise control does.

edit--

Seriously. Don't regear for 285s on 17s. Especially not for cruise control.

 

I totally agree with this, it's the cruise on these trucks that sucks, try driving the same stretch without the cruise and you'll find the truck acts much different.

Second on don't bother to spend all that money to regear, I run 285's in the summer with no problems, I just don't use the cruise much.

 

So regearing because of low power would be a good reason?

 

Regearing to cure transmission seek or poor acceleration after going to larger tires is a great idea. Regearing to fix your cruise control down shifting is fullretard.

 

I never use cruise control on this truck. It's terrible. Toyota did a horrible job programming it. I can do a better job myself.

 

If it makes you feel any better every vehicle I've driven has this behavior. And I've been in a lot of rental cars in the last couple years due to work.

 

My 2005 Camry SE did just fine....

 

mine does the same thing, it is especially bad if i use cruise control on a highway with a lot of elevation change.

Ive learned to adapt my driving style to gradually ease off the pedal while going up hill. This usually causes me to drop 5-10 mph, but the truck stays in the same gear.