Cruise Control Issue

[RichardTaylor]

Has anyone noticed that when engaged their cruise-control fluctuates just a little bit? What I mean is once my cruise is on my boost guage fluctuates about two or three pounds and you can just barely feel the motor accelerate and decelerate. It primarily occurs on level road with consistent terrain. You can't even see it in the Tach or Speedo but the boost guage goes up and down. My rig is a Graphite 03 quad-cab Laramie 4X4 with Automatic48RE an EDGE box and an AFE Intake System with A/Pillar combo Boost-EGT guage. She's SWEEEET!

 

[JVolpe]

Try it without the Edge box and see if it does the same thing. I had similar issues with a Predator fuel/boost box, basically same as the Edge EZ.

 

[Kirwin]

Cruise control engagement

Keep in mind that the throttle is electronic. The system may just be stabilizing out. Slight changes in throttle position are rapidly translated into changes in boost pressure and in EGTs in the power band of the truck! There has been discussion of this on the TDR in the past. Ken Irwin

 

[RichardTaylor]

Hey Kirwin, thanks for the input. I will try disconnecting my EDGE box but I would like to add that this problem just popped up on a trip to Vegas last month about 300 miles into the trip it started surging and now it does it whenever the cruise is engaged.

 

[Cattletrkr]

Assuming that the hills aren't too tall and the load isn't too heavy, my cruise will really make ya wonder. I will GAIN 3-4mph going UPHILL and LOOSE 2-3 going DOWNHILL. Simple math will tell ya that's about a 7mph swing, and it does this all the time, but it's MUCH WORSE loaded. There seems to be WAY TOO MUCH lag time in the computer, most of the increase occurs when cresting the hill and the decrease is at the very bottom. Both my '01 and '04. 5 acted the same and have done so since new. I never noticed a difference with or without the EZ in the '01, '04. 5 is stock. There is no TSB or programming fix, ya just gotta learn to deal with it. Oo. I have driven other vehicles that did the same thing, so we're not alone.

 

[BSchulte]

It is not your tuner! My stock truck does the same thing. As another post said, everything is electronic. It's the computer relizeing a slight need in power. Hence the minor feel in surge while in cruise control.

 

[Kennywould]

Has anyone noticed that when engaged their cruise-control fluctuates just a little bit?

Mine does the same thing, sometimes it will accel on a hill by 4 mph!

 

[RichardTaylor]

I don't think anyone is having the same problem as me. My truck DOES NOT SHOW ANY INCREASE IN SPEED OR RPM!!!! As I said above my problem is boost pressure increases and I can feel a slight surge..... Boost Surge Boost Surge Boost. This problem did not exist prior to half way to Las Vegas on a recent trip and now all the time when engaged.

 

[Cattletrkr]

Seems like yours is doing the same thing the rest of ours is, just a lot faster so there's no corresponding change in speed. Not sure what might be causing it. Did you try unpluging the EZ?

 

[Kirwin]

Cruise Control issues

Richard, keep in mind that the ECM uses several inputs to drive the program that runs your cruise unit. You won't necessarily see changes in the tachometer or speedometer as these are driven by the computer too. You will feel slight changes in engine power by the seat of the pants and the sound of the engine before a computer updates the speedometer and the tachometer on the dash. You want it that way. Its more important for the throttle response to be instantaneous that it is for the speedometer to respond to changes in road speed. If you want to try to repair this there was a procedure in the service manual that tried to recalibrate the cruise "engage point" as the system "learns" to make it smoother each time. I don't know if this procedure applies to your truck. It's my belief that your truck is working as designed. Remember as long as the oil pressure is greater that 7 psig the gauge will show 40 psig oil pressure. :--) Ain't computers great Oh wasn't it great when everything was mechanical and you could fix it when there was a problem! IMHO Ken Irwin

 

[RichardTaylor]

Thanks Ken, and everybody else, I still believe that the problem did not exist prior to this trip however I guess I will have to wait and see how things develope. Anyway now Ken has me concerned about my OIL PRESSUR!!!!!

 

[jmtandem]

cruise control slight surge

Richard,



My '01 does the same thing. It is noticable on level terrain and at relatively slow speeds, like below 55 mph. At faster speeds it seems to still pick up speeds and/or slow down on hills but without the slight surge. At first I thought the wind was blowing or something, but that is just the way it is. You won't see it in the tach.

 

[dodgerep]

HAVE NOT NOTICED THAT, but keep in mind that any resistance will change the load level of the vehicle and cause the turbo to spool, accept maybe down hill planes.

 

[dodgerep]

I dont think that is it, I use the attitude box, and just recently made 5,000 mile round trip with about 3800 on cruise, no issues.

 

[dodgerep]

what modifications have you made to your truck?

I know what you are talking about, and can duplicate the same thing at varying speeds. the resistance increases greatly over certain speeds, and the load monitor will go nuts on what seems to be a seemless country road. try it at lower speeds and see if that changes the effect.

 

[FDavid]

There was a cruise control TSB out a while back. Not sure if related though. One thing I have noticed on the bullydog outlook monitor is the fact that the injection rail pressure is never stable. It always fluctuates tremendously even at idle. This might be one of the reasons the cruise fluctuates as well. All these elctronics are a pita

 

[dhill]

My '97 did the same thing. Didn't do it until I put the boost gauge on it. Did it stock, did it after I added the TST fuel plate, did it after I added the after market injector pump. No Mph change and no tach change. Only did it empty, pulling my 5th wheel it didn't do it. Drove me crazy. I just learned to stop watching the boost gauge.



Dave