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Surge just off idle like I dumped the clutch

WarWagon

WarWagon

Well it hits on 7 of 8...
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Course it doesn't do this all the time but is almost predictable. Surge just off idle in a parking lot or going down the road it feels like I dumped the clutch and am winding and unwinding the drive train while rocking me back and forth. Bumpy roads tend to do this more. I have an off road strong throttle spring installed and replaced the FPR on the CP3. The #2 and #7 harness connectors were replaced. Fuel filter is new and made no difference. AFE mouthpiece.

I am not sure if I am bouncing the throttle back and forth from 0 where it cuts power and then back on or if there is something rocking me this hard from the engine. I will log throttle % and make sure this light reg cab truck isn't just tossing me around.

I want to apply the brakes and give it some throttle to steady it the hell out driving in a parking lot.

What do I need to start looking for with a scanner? What are the causes of surging on LLY's aside of the FPR? Would an EGR popping open at this low RPM possibly cause it? Does the EGR come on off idle?

It runs great at higher power levels.

Idle in gear not moving is rock steady.
 
Part of it is just normal diesel torque I think and idle control. My 6.5 use to get me like that rolling through a parking lot in 2nd gear just rolling through a parking lot.

Something would hiccup steering input that caused load on steering pump and or a foot small movement. Or a leaf spring unwind from rolling over a speed bump. Some little bump in power output. Then it was a hop, skid, and buck. I had to depress clutch and let it stabilize then regear. I think I just got use to it and now avoid the speed / rpm combo plus think the truck has gotten weaker and less snappy throttle response.
 
Note it did not immediately hop, skid and buck. It kind of built up but real quick. It would lightly surge then end in a hop, skid/bark / buck. Was worse when the engine thought it was going to stall.

Also, have thought it was a combo Diesel torque and high compression "braking" with some spring wrap/unwrap near idle control and just off idle power. With 1st gear the gearing is so low it dampens itself out but in 2nd gear there is enough acceleration/decceleration to back feed the powertrain. 3rd gear might be high enough that engine isn't going to wrap springs so easy????

Again best way for me was to clutch and let the truck slow or let engine restabilze then regear. Sometimes I will do a quick rev with clutch in to try and clear and reestablish idle fuel rates and take foot away from go pedal.
 
Is it stock or tuned? Many times if it is custom tuned the B1001 table will cause this. Check what the fuel pressure is doing just off idle and make sure desired and target are staying close to each other. And LLY's have a unique throttle table in them that I'm not real fond of. it tends to cause the RPM's to jump up real quickly. I ask about the tuning because I thought I read awhile back you had tryed somebodies custom tuning for cruise control surge.
 
Before and after tune it is the same. I was concerned that the LLY throttle opens quick to where bumps can induce a surge by the pedal...
 
Since you have a larger mouthpiece on it, does it have the current software flash for the LBZ mouthpiece(the AFE piece flows like the LBZ mouthpiece). Is the MAF clean? Check the fuel pressure, and fuel rates when it does it and see if there are any fluctuations in it.
 
I had Killerbee log the issue and he made corrections to the tune to eliminate the surge.

IMO The truck was literately throwing me on and off the accelerator even with a heavy throttle spring. These regular cab trucks are pretty light vs. the crew cabs.

Now I have a surge free parking lot experience and smoother on/off throttle in reverse. I couldn't be happier as I was going to simply get rid of it if this couldn't be solved.
 
The LLY throttle mapping is pretty sorry if you ask me. I know some people prefer it over teh LB7's, but I never liked the looks of how it was set-up.
 
The factory "parking lot surge" reflash that I had put in my LLY solved it for me, but, yeah, scared the bejeepers out of me first time it happened.
 
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