Chugging/Surging between 1,000-1,300 RPM

npe3484

npe3484

I hate ATF
Joined
May 10, 2009
Messages
792
Any thoughts as to why my truck would surge/chug (don't know how else to describe it) whenever it's between 1000-1300 RPM? Truck has 5x14's, comp DV's, DPC billet single, and is pretty much stock besides that. Adjusting the TV cable helped the problem a little by raising the shift points but it still sucks trying to drive around the neighborhood.

I was thinking that the line pressure might be too low with a stock VB and the fueling mods.
 
Does your pedal seem very sensitive? I am running 5x14's with the Comp DV's, and it is a real sensitive pedal, causing it to buck/jerk real bad. It did it once we went back to summer fuel. I've got 4k's in it now, they are set a bit loose. Still does it, but not nearly as bad as when it was tightened up.
 
Pedal isn't sensitive at all. The bucking will happen in any gear, mostly when the speed is too low for that gear (i.e. 2nd gear @ 12 mph, 3rd gear @ 25 mph, etc).

Do you think messing around with the AFC tuning could have any effect? One other member brought up fuel pressure as a possible culprit. I've got around 25 at idle but it drops to 10ish under any load, then creeps back up to around 20 cruising. This is with a new TorkTek OFV, OEM Cummins lift pump, deleted pre-heater, new filter, and clean pre-filter/strainer.

The injectors are from Disturbed Diesel and are only supposed to have ~5,000 miles.
 
My 95 with 191 dv's does this as well. It is not noticeable with the stock ones and is worse when I'm due for a filter change. Also, raising the fuel pressure by slightly stretching the spring at the return seems to have helped.
 
I had the same problem with mine. A cheap external fuel pressure regulator set at 30-35 PSI fixed it.
 
I'll try to adjust my OFV this weekend and see if that changes anything,
 
My truck does the same thing from 1000 to 1800 rpm if I'm just running light on the pedal. If i roll on into the throttle it will stop. OFV adjusted to 30 psi @ idle and still does it. Can't tell what started it cause all my upgrades where done at the same time.
 
Mine does it when its cold in the mornings mostly..... although changin a dieng shur-flo pump out for a new fuel lab, an setting my fuel to 35psi @ idle and 2500rpm free rev has definately helped some.... 4k springs set @ initial +3 clicks.....
 
Adjusted AFC and took some preboost fuel out helped a little. Made the bucking less violent but it's still there. I was thinking some sort of traction bar would help because mine does it so bad the tires will bark when it surges. Might not eliminate it completely but help.
 
Try stuffin another spring on ur throttle linkage on the pump an see what happens..... this fixed mine, although I like a light peddle and just deal with it now..... doesn't buck that bad.... an only till the T stat opens.
 
My truck does the same thing, however im not real sure if its to the extreme that your trucks were. Mine is worse when cold but when just grandpa'd around it is a little worse than when rolling into the throttle heavy. Im thinking mine may be because of fuel pressure. Have yet to get a gauge installed and stuck at school.

Mine has an odd kicker to it though, when the weather is warmer it has a lope at idle and cooler weather helps tame it. Awhile back from my description Weston said it sounded like a siezing plunger... Can I ask how many miles are on your guys' pumps?
 
My truck has 317,000 miles on it.... pump was done about 70,000 ago,but barrels were untouched.... I had bent gov studs and some broken stuff inside gov housing
 
My truck surges ever since I put my ddp stage 2 injectors in my 96. It also jumps in 3rd gear so bad I have to shift to 4th at about 1800 rpms. My linkage springs are good so I don't know What it is.

It will surge at low rpms in 4th and 5th gear. I also have a new lift pump.

Sent from my SCH-I500 using Tapatalk
 
Forgot to mention that my pump has no plate, 0.100" taken off the barrel, stock washers swapped out for fender washers, stock spring stretched and starwheel is pretty far forward, and the preboost screw is a couple turns past touching the diaphragm.

I'm sure the tuning isn't perfect, but could it be causing an issue at such a specific RPM range?

Truck has 299k on, pretty sure the pump has never been off.
 
My truck has sdx 5.014's, gutted afc, 3ks set at intitial and 3 clicks, and 15.5* timing. Has 306k on it.

Im not sure how tuning could make them do it by any means. I could be very wrong but I just dont see how that could affect it.
 
Actually, I think my AFC is gutted as well. I'm pretty sure I took the AFC lever out to check my max boost. OOPS! LOL
 
Ha! the things you remember sometimes.
I really think mine is something to do with the pump and the mileage.
 
I'm having a brain fart at the moment... Does a gutted AFC affect pre-boost fueling and fueling below ~10 psi? I bet that's why my truck was hazing fairly heavily the entire 70 mph trip from MD to SC.
 
With a gutted afc you would have complete rack travel at anytime depending on foot placement vs. the afc foot dependent on boost.
 
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