Throttle Surging and Pulsating

C

Cbush314

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Mar 7, 2012
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Just picked up an 06 not to long ago that had a Smarty JR and I didnt like it so I had EFI Live installed. Every since then the truck pulsates and surges when you have the cruise set, never did it before with the Smarty, and has a little surging and pulsating with your foot on the pedal at speeds around 45 MPH and up. Anyone else have this issue?
 
It's there as we speak. Just figured someone on here might have had a similar issue...
 
Probably a steep transition in fueling. Right where you are cruising the tune probably is going back and forth between a couple of pulse width or rail pressure cells that are not very smooth transition area. While testing some stuff I built a tune that did what you are describing at about 40mph. That was the cause of mine.
 
what superwagon said probably something along the lines of that. I had that pulse hit before and it was quite ruff.
 
You are going to need to data log the area that you are having the issue and your tuner will need to fix the tune. If it is indeed tuning related.
 
Ok, so I had the truck flashed back to stock and the pulsating seemed to go away. When the truck was then reflashed, the files were corrupted due to not unplugging my Edge monitor and DSP5. So then custom tunes were written from scratch. Now I am still getting a lttle surging still. I've talked with Exergy Injectors and they asked if the high pressure crossfeed tubes were replaced and in fact they were. My lift pump is in time or tuned according to the shop who tuned the truck. I'm not sure if its the 100hp injectors paired with the tuning or the tuning in general is the issue. Banging my head agains the wall and not enjoying cruise controll at all...
 
I have an 07 that does the exact same thing when I command too much fuel pressure.
 
superwagon said:
Probably a steep transition in fueling. Right where you are cruising the tune probably is going back and forth between a couple of pulse width or rail pressure cells that are not very smooth transition area. While testing some stuff I built a tune that did what you are describing at about 40mph. That was the cause of mine.
Click to expand...

thats' EXACTLY what i was told. i agree with the concept and it makes sense, but i have modified probably 10 diffrent tunes, smoothing out cells, logging the area and cruise control KILLS me. i would pay someone to fix it. ive been fighting it for over 2 years.:doh:
 
The RP boxes were doing this back around '05. I would dig around with the rail pressure.
I know the Edge EZ couldn't be driven on cruise. Made me bat **** for a while.

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I'll try to post an example later of what you need to look for in your duration table. I use UDC but the issue is still the same. You need to follow every column (load in UDC) from top to bottom and make sure that as pressure increases your duration decreases, and then do the same thing with every row (rail psi in UDC)- duration should increase as you increase engine load. If you are doing your own tuning and can post a picture of the values for your rail pressure and duration maps we might be able to help you out.
 
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