Engine/Transmission (1998.5 - 2002) cruise control

[dj]

Does anyone have information on adjusting the sensitivity of my cruise control? After topping a hill, my cruise control will engage and dis-engage several times while coasting down the down hill side. My truck has the a 245 hp. H. O. engine and the total electronic cruise control. When towing my 7500 lb. travel trailer, the problem is not too noticeable, but is a real bother when running empty.



Thank you for any help or information.



Dean



Mesa, Az.

-- email address removed --

 

[Sageair]

Dean

I have noticed the same thing you describe in my 2002 H. O six speed but I attribute it not to the cruise control but to a phenomenon known as bootstrapping. When the cruise control decides that your speed is low it calls for throttle to increase speed, but since your turbo was spooled down while coasting it spins back up which actually gives more power than the cruise control called for. Now you are going faster than the selected speed and the cruise control calls for a throttle reduction which of course causes the turbo to spool down again. This cycle continues ad-nauseum. I am of the belief that between the fact that there is no slack in the drivetrain with a manual transmission and there is so much power available to increase speed when called upon to do so you experience what you describe. I just punch the cancel button for the cruise control,use the foot feed and wait until I'm off the hill to re-engage the cruise control.

 

[Behr]

Hi fellows...

Well here I thought mine was the only one that did this.

My 98 with 5sp was no problem... but my 2001 5sp is doing just like what yours is. It gets so annoying when drving highway alongs the flats. . it just goes for more gas then backs off... then back on ... . finally I just take my foot and gently hold constant pressure on the pedal.....



I like the sounds of the explanation with the turbo... but just seems odd that my 98 did not do it... unless because it was the 12V ..... maybe that was it... .



Something to think about... ...

 

[Mundgyver]

Ah, Hysteresis: to be behind, come short, later, behind, a lag of effect when the forces acting on a body are changed.



To solve this problem, you will need a precision adjustable needle valve to put into the vacuum line to the vacuum servo on the servo control module that set under the battery. By turning it almost all the way off and allowing only a minute amount of vacuum to take place, you will slow the throttle affect and thereby dampen out your surge affect.

 

[Behr]

Thanks Mundgyver for the tip... .....

At times it got so annoying with the constant surging... but like I said in my earlier post it never did it with my 98 12 Valve... . but this 2001 24V is real bad... .

This will probably help the fuel economy too.....

Thanks again... ...