throttle surge on cruise control at light throttle

SixOhh

SixOhh

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Aug 4, 2008
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i could use some help with this one guys... id like to pick some brains before i start randomly replacing sensors!

my CR starts surging the throttle ONLY when im on cruise control and ONLY when its under a very light load (normally after topping a hill or coasting down an over pass). it has been doing this for years and i always thought it only did it with the smarty on. after i installed my RP sensor i noticed it more... not because i felt it more but becasuse i can actually see the surge via Rail pressure readings.

it has gotten slightly worse over the last 6 months so i started probing around.
first i changed some smarty settings and then i finally tuned back to stock and hit the freeway..... the problem still exsists w/o smarty but its not as harsh. after topping a hill i cant feel it as bad but its still there and i can see it on the gauge.


my first assumption was the RP sensor itself because its my second one (my quadzilla RPG claimed my last one) but then after talking to a fellow diesel mechanic he suggested the speed sensor in the trans. and that the programmer could be amplifying the sinal and making it worse.

now its gotten bad enough that i find myself tapping the brake after coming over a hill because i know its coming and the way its surging AND i know its gatta be he11 on u-joints!

i am starting to wonder if it could be in the speed sensor because every now and then i feel like my cruise control has a hard time resuming to the same speed. on the other hand, what would that have to do with my rail pressure surging? could it be a problem coming from the cp3? possibly the FCA messing with RP?

any thoughts on this?:nail:
 
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several times over the years. went from the 4.4 beta to the revo then tnt. they all do it the same...... the RP levels and power settings dotn make any difference either.

im at a loss considering its only does it on cruise!
 
my early 04 used to do that, but it was the old TNTR file...

never had the problem in my 06, and my current 03 has no problem either. I always assumed it was the older software.

bump your cruise speed up to 85-90, and it'll go away :p
 
You definitely know what im talking about because its worse at slower speeds on cruise. If im rolling thru a small country town at about 50mph... forgettabout it!!! The truck will start jerkinging me out of the seat! And at 90, well let's just say there's enough head wind to make the truck push back on its own...

Im running the most recent version of. Smt
 
may want to look into a map sensor too, they will cause turbo surge. ive always had the problem as well and the more fuel i put to it, the more violent it got
 
CR might be different but on my friends 01, we had a Smarty on it for a year.
It had a cruise surge like you described starting from the time we put the Smarty on it, even when we unloaded it it still had the surge.

I'm not knockin Smarty at all, I still like their products
 
dieselkid6 said:
may want to look into a map sensor too, they will cause turbo surge. ive always had the problem as well and the more fuel i put to it, the more violent it got
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as stated in my original post, it does it more as the throttle (load) decreases. i can give it fuel and it will immediately go away.

i really wish i could pinpoint the problem. its not the smarty but the smarty amplifies it for sure
 
You may need to have the cruise control relearn. From a Chrysler bulletin:

If the vehicle operator **repeatedly** presses and releases the SET button with their foot off of the accelerator (a "lift foot set" to begin speed control operation), the vehicle may accelerate and exceed the desired set speed by up to 5 MPH (8 km/h) and then decelerate to less than the desired set speed before finally achieving the desired set speed.

The speed control has an adaptive strategy (ability to learn) that compensates for vehicle-to-vehicle variations in speed control cable lengths. When the speed control is set with the vehicle operators foot off of the accelerator pedal, the speed control "thinks" there is excessive speed control cable slack and adapts (learns). If "lift foot sets" are continually used, the speed control overshoot/undershoot condition will develop.

To "unlearn" the overshoot/undershoot condition, the vehicle operator has to press and release the SET button while maintaining the desired set speed with the accelerator pedal (not decelerating or accelerating), and then turn the speed control switch to the OFF position **(or press the CANCEL button, if equipped) after the speed control has been engaged for 10 seconds or longer.** This procedure must be performed approximately 10-15 times to completely unlearn the overshoot/undershoot condition.

Hope this helps.
 
Thanks. I have been beating my head aginst the wall trying to figure this out on my 02. I realy hope this works.
 
dodge2003 said:
You may need to have the cruise control relearn. From a Chrysler bulletin:

If the vehicle operator **repeatedly** presses and releases the SET button with their foot off of the accelerator (a "lift foot set" to begin speed control operation), the vehicle may accelerate and exceed the desired set speed by up to 5 MPH (8 km/h) and then decelerate to less than the desired set speed before finally achieving the desired set speed.

The speed control has an adaptive strategy (ability to learn) that compensates for vehicle-to-vehicle variations in speed control cable lengths. When the speed control is set with the vehicle operators foot off of the accelerator pedal, the speed control "thinks" there is excessive speed control cable slack and adapts (learns). If "lift foot sets" are continually used, the speed control overshoot/undershoot condition will develop.

To "unlearn" the overshoot/undershoot condition, the vehicle operator has to press and release the SET button while maintaining the desired set speed with the accelerator pedal (not decelerating or accelerating), and then turn the speed control switch to the OFF position **(or press the CANCEL button, if equipped) after the speed control has been engaged for 10 seconds or longer.** This procedure must be performed approximately 10-15 times to completely unlearn the overshoot/undershoot condition.

Hope this helps.
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i tried that and nothing changed, looks like i have a different problem, i am being told that i am feeling the post event coming off and on.

guess i am now in the market for SSR or EFI live software, guess it was time anyways.
 
no, never. i have a fresh set of 50 over's coming from exergy.

what are you hinting at? truck has 140k on it, i have my amsoil tested regularly, the truck doesn't haze or smoke stock. no ticking, knocking or the like, no startup issues.... truck has had and AD 150 from day 1... etc etc...


i know the truck is about due for the injectors considering the average life span and im hoping between the new sticks and crossing over to EFI live soon it problem will be eliminated.

and im learning as i go, so im not complaining.....
 
Some fuel rail pressure issues are due to the injectors not installed in the proper torque sequence. That's why I asked
 
Mine started surging on Cruise control (I can feel surging with pedal but slightly) after installing the Air Dog II 165, Arson III, T&C Diesel's Wild Rail and CPRV.... I did them all at once , so I can't pin point which one caused it..

The AirDog was shipped with a 22-27 PSI spring in it... I'm gonna swap it out for the 15 PSI spring to see if it helps... I read somewhere that the higher pressure to the CP3 causes surging but can't remember where..:doh:
 
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Get with swole on this issue...tell him you wanna talk to mike can't think of his last name..He's knows what this issue is..nothing serious
 
Sticky said:
Get with swole on this issue...tell him you wanna talk to mike can't think of his last name..He's knows what this issue is..nothing serious
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Hey sticky,

Could you forward to Big Swole? I don't have enough posts to send Big Swole a PM or E-mail by forum rules :doh:
 
Sticky, you're thinking of the issue I'm having with my feed pressure being too high for my Dmax pump (top cp3). I can't get my fass to reduce the pressure enough. Causing high RP at idle (espicially when cold). The warmer the engine gets and its components, the more normal my RP stays..

This doesn't cause a surge for me though, only a major Lope when its cold.

With this guy only having one dodge pump with an arson III kit, I don't think this is his issue.
 
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THANKS FOR THE REPLY'S GUYS (Sticky & Swole) I'll get it figured out... Todd @ T&C Diesel said 22 PSI is way to high! get it down to 15 PSI. I'm swapping the springs out... We will see, and I'll report back.
 
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