I am hoping that I can find questions to this engine problem that seems to plaque alot of people on here, but no definate answers have been pin pointed. That I have seen or read.
Problem: Excessive surging of the engine, mostly at low rpms like cruising thru town, it feels like the engine finds alot of power and wants to take off, then it loses power and slowes down. over and over and over, the funny thing about this problems, is that it has no pattern, it happens more when it is cold, but will also just not as often when warm. Meaning air temp, and engine temp. Also sometimes, not very often after going down the highway and take your foot off the throttle to turn slow for a corner, and put your foot back into the throttle, there is nothing there, NO THROTTLE at all. let off and push again and it is back. HUM Yes I have replace the Throttle pedal sensor, no appearant changes. even went so far as to spray WD 40 on TPS and IVS for moisture problems or anything, no apparent changes.
Something else I did was to unplug the ICS and the problem went away, drove it with no problems at all, everything worked normaly, except a lack of power of course, and the SES light on.
Before you jump and and say well easy enough replace the ICS that is your problem, think about this, when i put the cruise control on all problems go away, trucks runs perfectly up and down hills, thru the valleys all the way to grandmas house, doesnt miss a beat, but take the cruise off and bam, back to riding the wild horse, bucking, kicking, surging, etc.
WHY WOULD IT RUN FINE WITH CRUISE ON, BUT RUN LIKE CRAP WITH THE FOOR PEDAL?
ANYONE have some help with this, I am getting 17 - 18 mpg hwy, and 12 -13 mpg towing, (at the pump) I have 150000 miles on the truck, did an oil sample from black stone, and under average on all wear metal, they even complimented the motor. this bucking bronco is driving me crazy... HELP I dont want to throw money ontop of money at it for nothing,

OH to note, when i turn my edge chip back to stock, the problem is still there, just not as noticable as when i have the chip running, I am thinking that the chip just enhances a problem that is already there.

Sorry this was so long, but I see so much info out on the net about this problem, and no real fixes yet,,, so all of you diesel brains out there, input needed, us not so smart guys need you....

And no codes are showing, had it check dealer,,, no help. they just scratch that grey matter....LOL

 

I know I know I know!!!!!!!!!!!
My truck did the same thing i thought it was the APPS but it was not.....
I had a low boost code, and replaced the MAP sensor (with a used one, lol) and have not had the problem sence, its been like 3 months!!!
There was alot more diag into the MAP that determined it bad, but thats the short version

 

Tyler thanks for the reply, I did replace the map sensor about a year ago when I first started noticing this problem, the problem went away, but then came back later on, dont remember the time frame and has progressively gotten worse. The wierd thing about this problem, just like I have been reading is that this is a come and go problem, sometimes it is really bad and sometimes it is not even there, that is the confusing part, if it was there all the time we could all find it I believe.
when I pull my trailer 7000 lbs i dont notice it so much, assuming the reason is because I am into the throttle most of the time, and even empty as long as I am in throttle i dont feel it, only shows up under light pedal pressure.
I also thought about the TPS (throttle pedal sensor) and replaced it about 6 months ago, the problem kinda went away, but came back. havent replaced the IVS yet.
The really puzzling thing about this is that this is a hit and miss problem. If it was a sensor i am thinking it would be a constant problem, not hit and miss. Maybe thinking outloud here, we are looking at a plug or wiring issue might be a good reason to get the fire going in the garage today and start crawling around this motor unplugging all connections checking the pins and looking for chafing on any wire.
I dont know just some ideas, am loosing my hair on this one, like everyone else. come on guys surely someone out there knows something...

 

When mine did this, I just ordered the entire pedal assembly from parts guy Ed, no more issues. The fact that its fine with cruise on tells me its in teh pedal assembly, its drive by wire on these trucks, drive by pedal wire, or drive by cruise wire, in this case its the pedal I would bet. Think it was not that much money if I recall, under 100 bucks for the whole assembly.

 

i thought it was the pedal too, but mine is fixed ever sence i did the MAP sensor. but yeah it can be a hit or miss. mine got really bad and then never happened after the MAP. I tested my Map with a cyl leak down tester set to 10psi monkey rigged too some hose and reducers to the sensor and checked what my scanner read and the Volts. I dont remember how far off it was but it was bad so i replaced it. I had picked up a throttle pedal(used), but i have an early 99 and it didnt fit so i took it back.
I really thought that would have fixed your problem i didnt expect you to have replaced it already...good luck, you may try another one just too see?

 

I am very interested to see how this turns out. My truck has a little jerkiness to it. Very little but enough that I notice it and don't like it. I wonder if I'm on the same path you are.
Could it be maybe the IPR or ICP?

 

you may try unplugging your APPS and check the connection. When i replaced my MAP i remeber i also was going to replace the APPS, but the connectors on mine didnt match the plugs on the one from the wrecking yard

 

Have you unplugged the EBPV at the turbo pedestal yet? If it is cold out, the EBPV will come on at low engine speeds, Such as driving through town, once you get on it, it'll come out of it and run great, until you slow down and go back to cruising at city speeds.

 

I would just about bet everything I had to a bad pedal assembly. I have fixed many trucks with the same symptoms by replacing the pedal

 

I also replaced a pedal due to a surge that Ford couldn't even diagnose. It worked like a champ. Mine had adjustable pedals. From Ford it was almost $700. NAPA sells one that's about $175. That's what I bought and it works great. No more surge, even with the DP Tuner.

 

i got lucky then, mine issue was just a bad connection becasue its been fine ever sence i ALMOST pulled it out. Glad to here your problem is fixed!!

 

Mine is the opposite of you're. Mine only does it in curse control.Like a little jerk back in forth. Not really noticable but I notice it. I thought it was the tuner, am I right, its a dptuner. Take it off curse control and its fine? Chet

 

My early 99 started to do this a couple weeks ago; only with the cruise control on. It happens when there isn't much of a load on the engine. It does this pulsating throttle thing. It doesn't change the speed of the truck, just an annoying pulsating thing (about a pulse every second). I think I'll be replacing the VSS. It doesn't do it driving with the pedal at the same speeds; I have no idea what else would be causing it. By the way, if I use the pedal to add throttle to the cruise momentarily, the pulsating disappears.

Bryan

 

when I had a surging problem it turned out to be my ipr was bad.
First i rebuilt it with no change but when i replaced it with new surging ended

 

bryanj, if you fix yours let us know. It is exactly what mine is doing to the Tee. Thanks Chet