I am driving a 2000 3.0 automatic with 4:10 gears and 31" tires. I also have a 99 with a 3.0 automatic with 3:73's and 225/75/15's. The 99 seems to have alot more power. The 2000 is a florida truck and I was wondering if the altitude settings could be why the 2000 doesn't seem to run as good. Any thoughts? BTW No CEL's or missing, just less power.

 

could be the tire difference...

 

yeah maybe but I figured the gears would offset that.

 

If you think its the altitude, disconnect the battery for a few hours to reset the ECU. Then hook the battery back up and it will be like it was from the factory with a clean slate.

 

that is pretty interesting, I would think that the gears would offset the 31's... maybe one was abused more than the other time for a tune up??? maybe?

 

I think its the gears.

 

What mountain peak do you live on? Its unlikely you are high enough to make performance difference that noticable. Plus you are comparing two vehicles with different drivetrains and different tires.

 

Barometric pressure compensation is automatic and continuous with both trucks. Reinitializing the PCM will not change anything. The difference between the two lies somewhere else - axle ratio, tire diameter, weight, engine condition, etc.

 

Well the trucks are basically the same except gears and tires. Same trans and only one year difference on the motor and both are flex motors. Actually mileage is pretty close also at 145000 and 141000. The "slower" truck was bought new in florida by an old man. The faster truck was bought new in pittsburgh by a 30 year old. It isn't that the truck runs bad, it just doesn't seem to have the power of the other one.

 

With 4.10 gears and a tire that has about 6.77% fewer revolutions per mile that gives you about a 3.88 ratio, figuring stock was a 235/ 75 15 on the 2000.

See here:
Tire Size Calculator - tire & wheel plus sizing

I assume the 3.73 had the 225's as stock?

Is the 2000 having breathing problems, in or out? I replaced the cat, fuel filter, o2 sensors in my 95 and it was like new. I did some other stuff but it all made a difference. It will make it to the redline now, the power flows. Before that it was a wicked dog.
I did all that around 128- 135K. It runs better with 146k now than with 66k when i got it.
Everyone said the cat should never have to be replaced. I am glad I did it. Though your mileage may vary.

 

You got me thinking so I went to the gear calculator on TRS and it comes out as an equivilent to 3.74 so actually with the 4.10's and 31 inch tires the gears are a wash as I originally thought. I guess I'll have to dig in a little deeper maybe clean the throttle body and map sensor...

 

maybe try the throttle cable mod if you can. I thought about that on my way home tonite.

 

I did that saturday at our meet. It did seem to help a little.