bad surging problem. need help!!

Out Back 4x4

Out Back 4x4

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May 12, 2011
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I have a 2003 h.o.6 speed. Truck has 116k on it. Recent 150hp injectors, 6.7 cp3 upgrade, fass 150 among.other things. When accelerating up to or past 1800 rpms, the truck surges and or misses. When trying to keep a steady pedal at cruising speed at or above 1800 rpms and 15k rail pressure, it starts to surge and you can watch the rail gauges surge then the fuel pressure gauges proceeds to do the same. But when at full throttle it runs fine. I have ran the scanner on it, no codes, and have tried a different cp3 regulator. Also have ran with and without ssr to no avail. Does the same thing. Could someone please help me?!


Jake


__________________
 
I wish I could help! But mines doin the same EXACT thing and I'm clueless on what it could be! I've changed my regulator also and still does it. I sure hope someone comments
On here to help us out! Haha
 
I've been looking for a cure for years....haven't found one yet.
Look up an old thread of mine titled Sick of the 70 mph surge and see if that's the same issue you have.
 
Have yall chacked the apps? Make sure the voltage matches the voltage on the sticker on the sensor. If not adjust it, Ill bet it helps a ton. It did on mine a while back.
 
duck, what years to the apps apply to? i did some reading up on it months ago but for some reason i had come to the conclusion that it was for the older trucks
 
my truck only does it when on cruise cont. so i think i have a different issue.
i have a used RP sensor and FCA on the way for diagnosis purposes ( i can see the surge in the rail) and if that doesnt change anything im going to lean twords the speed sensor
 
SixOhh said:
duck, what years to the apps apply to? i did some reading up on it months ago but for some reason i had come to the conclusion that it was for the older trucks
Click to expand...

98.5-04

And I believe some 04.5's had the APPS mounted on the head also
 
SixOhh said:
my truck only does it when on cruise cont. so i think i have a different issue.
i have a used RP sensor and FCA on the way for diagnosis purposes ( i can see the surge in the rail) and if that doesnt change anything im going to lean twords the speed sensor
Click to expand...

^
thats what i would do if it was mine. hope you figure it out.
 
What is your line pressure before the cp3???

It shouldn't be any higher than about 15 psi, anything higher can cause erratic symptoms even surging because you have to much line pressure on the low side of the pump.

Just a thought guys.
 
I have the same thing.... right at 1900 rpm my rp guage starts to go crazy at about 2200rpm its back to normal. I had the SSR for awhile and i could feel the truck surging in that rpm range, now that I have EFI and tune from Rob i cant feel the surge but i can still see it in the gauge and it driving me crazy.... Floor It Stage 3.5 cp3
 
Running 16-17 psi fuel pressure. Can see surge in both gauges with cruise control on and off. Only time it doesn't do it is if you're under 1800 rpms or under a heavy load percentage.
 
same here. on a heavy load its consuming too much fuel to be a problem.
 
SLVRBullet said:
What is your line pressure before the cp3???

It shouldn't be any higher than about 15 psi, anything higher can cause erratic symptoms even surging because you have to much line pressure on the low side of the pump.

Just a thought guys.
Click to expand...


really,
my AD pressure is always 20-25 psi. i've never changed the spring, its just always been that way..... HMMMMMMM


i wonder why the added line pressure on the inlet side can cause issues? all its doing is going to high pressure anyways...
 
Does the outside air temp have anything to do with it being less or more surging? Different ball game, but my 02 surges like a mofo when outside air temps are below 50 and the AIT reads below 100 or so. Never found a cure for this either whether it is the same or different.
 
i cant confirm that. my truck has been doing it for over a year but its been bad all summer... in texas its always hot in comparison so its hard to tell!

Im also wondering if TC is onto something as well. could it be an issue with the MAP if its constantly getting different pressure readings and then causing it to change with the tables programmed in the ECU?

i have seen the tables in the ECU with efi live so i can understand how this could happen...
 
Mine doesn't matter whether It's 50 or 100 degrees outside. I cannot keep a constant cruising speed. And Unbroken...it seems the same problem as mine
 
I agree with duck. Those engine mounted apps were horrible giving problems at certain pedal positions. I thought they were only on 1998.5 - 2003.5 trucks. If you can't watch voltages then find someone to swap with - very fast to try. Was it doing this before injector swap? Uneven fuelling can cause many stupid surging problems.
Good luck and keep in touch.
 
BSwope said:
I have the same thing.... right at 1900 rpm my rp guage starts to go crazy at about 2200rpm its back to normal. I had the SSR for awhile and i could feel the truck surging in that rpm range, now that I have EFI and tune from Rob i cant feel the surge but i can still see it in the gauge and it driving me crazy.... Floor It Stage 3.5 cp3
Click to expand...

Have you got any data logs?

Cheers
Cindy
 
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