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Cruise control surges 3 MPH.

WarWagon

WarWagon

Well it hits on 7 of 8...
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2005 LLY. Cruise control surges 3 MPH. Even after the FPR replacement I get a minor light throttle surge. When I turn on the cruise control it will immediately surge 1-2 MPH and then return to the set speed and work ok above 60 MPH. At 35 MPH it will constantly gain and loose 2-3 MPH.

Is this common?
 
The surging when you hit the cruise is normal, but not while the cruise is engaged, from what I remember. I rarely use the cruise below 60, however.
 
My LBZ would gain about 3MPH when going up a hill to keep cruise above the set point. I think that's the result of poor programming by GM not taking the spool time in effect.
 
My LB7's cruise works less than desireable as well. It will lose about 2 MPH before it will begin to fuel more, and then it floors it and downshifts the trans which I don't like. Once it kicks down it will go about 2-3 MPH above the set point, then goes back to the set point once I level back off. When I'm running on flat ground it holds pretty steady though.
 
THEFERMANATOR said:
My LB7's cruise works less than desireable as well. It will lose about 2 MPH before it will begin to fuel more, and then it floors it and downshifts the trans which I don't like. Once it kicks down it will go about 2-3 MPH above the set point, then goes back to the set point once I level back off. When I'm running on flat ground it holds pretty steady though.
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I never noticed mine do anything like that. If I set it at 65 the needle stays on 65 if I am going up hill, down hill or on the flat. Maybe your vehicle is too light.:hihi:
 
whatnot said:
I never noticed mine do anything like that. If I set it at 65 the needle stays on 65 if I am going up hill, down hill or on the flat. Maybe your vehicle is too light.:hihi:
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She's definately not to light as she is surprisingly heavy weighing in right with an extended cab 4X4 2500HD around 6800lbs. When I'm empty it will hold within a MPH, the numbers I posted are while towing a good sized load. I just think GM was a bit to laxed in bringing the cruise in for higher engine loads.
 
Hmmm... the rear axle was smiling when this happened so load is part of the issue.
 
Mine will surge some at set but is steady when it settles at speed. I've never used it below about 50 though. I remember my LLY was a bit more unsteady though.
 
Is it stock tuned?

There was an issue with certain Predator tunes with surging while using cruise but it was a quick fix with a latest revision update due to many complaints. My 04 surged as well under very light load with a specific tune.
 
Stock tune and supposedly the most recent stock reflash from the dealer.
 
Mine does the surge really bad....especially on hills but my predator programmer is old and not updated so that may be part of it. I never use the cruise on hills, drives me nuts!
 
It will disappear with a custom tune that refines the fuel pressure tables. Also, the LLY suffers from operator induced pedal feedback. When you replace the spring with a heavier one, it will feel more refined.
 
killerbee said:
It will disappear with a custom tune that refines the fuel pressure tables. Also, the LLY suffers from operator induced pedal feedback. When you replace the spring with a heavier one, it will feel more refined.
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Whose custom tuning will fix this? Asking because I know of several others that experience it.
 
You will just have to find someone who has been able to isolate the cause, specifically the relationship between pedal (including operator feedback), fuel pressure and pulse. 90% of all commercial and custom tuning is based on stock fuel pressure and pulse tables, near the problem areas. Finding a "ground-up" product is rare, but that is pretty much what the LLY needs for this specific issue. IMO.
 
I'll have to turn the cruise on and see if this was fixed with the tune.
 
killerbee said:
You will just have to find someone who has been able to isolate the cause, specifically the relationship between pedal (including operator feedback), fuel pressure and pulse. 90% of all commercial and custom tuning is based on stock fuel pressure and pulse tables, near the problem areas. Finding a "ground-up" product is rare, but that is pretty much what the LLY needs for this specific issue. IMO.
Click to expand...

Thanks. It sounded like you knew of a specific tune that would solve the issue at first.

I'll keep looking.
 
My LBZ does this as well as my Cousins 05 CC Dually, lly his has edge with juice mine is plain edge. They pic up speed with boost like said, never had either downshift up hills and we both run ~55-62mph everywhere.
 
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