Ford 7.3L Power Stroke (1999-2003) :: Low Power Cruising At Speed At Low RPM
Feb 11, 2016
I've been trying to track down a lack of power with my 7.3 for a few months now. I've had the truck for 8 years and there's just something off with it lately. When warm under a light load, such as accelerating while cruising at 40mph or going up a light hill at 30mph+, around 1100 to 1400rpm, there's just a distinct lack of power.
The engine starts lugging and the injector or valve noise increases dramatically until I push the throttle down far enough (60%+) for the transmission to downshift. Once it downshifts the engine sounds normal and takes off like it should.
At higher RPMs, it's seems to run okay, but it feels a bit down on power there. Otherwise, it starts great, idles pretty well with a slight miss, and no smoke that I've been able to see.
When it's dead cold in the morning, it seems to run better than any other time of the day.
I don't have any trouble codes other than a disconnected EPBV. One morning I did get P1670 when the engine nearly died when coming to a stop. I'm chalking that one up as a fluke due to a broken valve cover harness connector tab.
The truck has 170k miles and is mostly stock: AFE intake, 4" exhaust, and no muffler. It has an old Edge Evo programmer (yeah, yeah) that I removed a while back. I going to put it back on so I can monitor my EGTs.
The ICP, IPR%, and boost are all within spec. Buzz test sounds fine. CCT says #8 is bad with the grey CPS. Here's a datalog of a full throttle 70mph run.
[URL] ......
Recently I've decided to fix known problems:
HPOP line leak to the driver side bank
All Injector O-rings (black diesel in fuel bowl, suspicious oil consumption)
Replaced leaking intercooler couplers
EBP tube clogged, causing 0 boost sporadically, bypassed it by teeing into MAP sensor hose.
Various cam position sensors: grey (B), new dark blue (C)
Replaced leaking ICP sensor with generic sensor 6 months ago and unfortunately can't find original to test with. 2900psi without a tune seems a bit high, but reads consistently otherwise.
New fuel pump
Added service port to fuel bowl and measured 60-64psi at idle
Some things I have left to try:
Measure fuel pressure under load
Try out a parts store CPS I forgot I had.
Ziptie/secure broken valve cover harness connectors
View 14 Replies
Advertisement
I have a 2002 7.3 160k miles and recently it has been hesitating while cruising along at 35mph roughly. In park right off idle the engine does shake but if i give it a little more pedal the shake clears out. Not sure if that has anything to do with my issue but im just throwing it out there. Anyways cruising down the road the truck will hesitate almost like its not getting enough fuel the engine bogs then picks up then bogs and picks up but it i give it more pedal the truck gains speed and the issue stops and i can resume cruising at say 45 and not feel this hesitation at all.
On the toll road i never feel the hesitation cruising at 2k rpms. A problem that might of lead me to this issue was in the winter below 30 degrees i would drive the truck get to a stop light engine still cold or maybe warming up off the cold mark but when i go to take off from a light its like my fuel pedal doesn't work but the rpms will climb a little then the truck takes off and jerks really hard since i had the engine rev'd up. which made me think throttle sensor immediately or maybe the trans is having issues. since its warm out I don't have that issue now so i believe that it the trans. do you think maybe my hesitation now is also the trans? I never get a CEL. I did recently change the coolant temp sensor and now i am having this hesitation issue.
But I was told the ECM does not care about coolant temp on an auto truck so i dont see how that could affect my performance. Instead the autos monitor oil temp and the manual trucks monitor coolant temp correct? I had an issue like this with the truck years ago when i purchased it i was leaving the gas station on very cold maybe 10 degree day and the truck fell flat on its face and threw a bunch of codes but i let off the throttle and got back in it and it took off like nothing happened. So im not convinced the coolant temp sensor was defective from factory. But this old problem of not accelerating seems to be coming back to haunt me.... and i think its in a new form with the hesitation once in a while. I think i forgot to mention the hesitation isn't all the time!
View 5 Replies
Bought the truck 1000 miles from home, ran great, checked oil it was black and well used, coolant was milky and degas bottle had some pressure in it.
Drove 200 miles fine, 75mph lots of power, no smoke, no overheating.
While cruising felt slight stumble, and lost hot air from the heater (started blowing cold), saw temp needle move slightly (still under 1/2 mark) and pulled over. Truck stalled on the offramp, and I was not able to get it to fire. I checked oil and it was same dark black. Coolant was low, down to about 2.5 gallons.
Towed it home, oil change, coolant flush, new thermostat, rebuilt IPR, and it fired right up. Ran great, smooth. Noticed slight haze out of the exhaust at idle, and puffs of white smoke when on throttle. Checked oil and it was milky. Where to look?
View 6 Replies
I've been having problems with hesitation and a flutter at cruising speeds as well as erratic idle. I have a 2000 F-250 SD with 497K Miles. I was having poor starts during florida winter ( had to plug in a couple times) Had no oil coming out of #2 inject and #8 buzz was weak. Flutter was there and was the original reason I started digging. Right now the only code Im throwing with my chip turned off is a P0470. I cleaned the tube and the sensor but its still throwing.
I have recently replaced all Injectors, Glow Plugs, Valve Cover Gaskets & Harnesses, CPS, Fuel Pump, ICP was replaced before new plug no oil showing.
Mods: 6637 Air Cleaner, TS-6 Chip
Truck has mad power now no problem starting. Its really starting to frustrate me Ford dealer wont troubleshoot unless I remove the chip. I feel like it should be something simple because on the throttle it will set you back in your seat cruising at 70+ no flutter ..... but slow down to 50 55 in traffic and let off the throttle when you start to ease back into it 1500 - 1800 "buck buck buck" if I monitor ICP pressure I see a fluctuation in psi of about 200 -300 psi (1400 to 1200 or 1000 to 800) . If I throttle harder it will stop or let off the throttle. I can feel it do it sometimes before the TC locks so I dont think its a TC issue. I even tested with OD off and I can recreate. The magic area appears to be 1500 - 2000 rpm....
View 6 Replies
Like the title says my truck has been stalling while driving. Accelerating or cruising it dies for a second, two at the most, and then just keeps chugging along again.
I thought i'd fixed the problem last year when I did injector O-rings and 50 cented my UVCH. It hadn't done it since, until two days ago. Started out with a two good solid stalls while gently accelerating up hill. I had thought maybe my fuel pickup foot had finely given up the ghost because I was below a quarter tank. But I filled her up full, and then she did it again about 50 miles of driving later.
I didn't catch the first four stalls on my torque app, because I'd just recently decided to stop logging every trip, with the thinking that it had been half a year problem free, why keep logging waiting for something that isn't going to happen. I did catch the 5th stall on the torque log. But I'm having trouble trying to figure out where it happened in a 30 min log.
First question where would yall start in tracking this thing down? Next what data actually should be logged? I think I've got some extra stuff in my logs that isn't necessary, and is maybe bogging down the system. I get one data point per second resolution on my logs. Are there ways to improve the resolution, will getting rid of some PIDs work?
Lastly I need to attack this thing smartly, without throwing time and money at unneeded parts. I had surgery and I've been out of work for 3 months and I'm looking at another 6 before I'm making money again, and there is no unemployment for the self employed. Also I only get 3-4 light weight upright hours a day to work, exceed that and I'm back on the couch battling swelling for a week.
Also is there anything I can do while driving to "flag" the stalls so I can find them more easily in the logs?
View 14 Replies
I've been getting a surge or revs when getting up to cruising speed before it drops into overdrive or or a constant speed. Happens around 1800-2200 rpm before up shifting to the next gear. More noticeable if under a load or going up a grade when it will hold gear longer before shifting. Only thing I can think of that would be related is the truck does lack some power on a cold start for the first couple miles before getting up to temp. I've cleaned the ebp sensor and it appears to be working correctly, reading within .1-.2 of BAR/MAP key one engine off. VGT solenoid is clean but have no real way to tell if it's working correctly. Other values icp/ipr temps fluid levels appear to be correct. Just changed the oil and it continues, changed the transmission oil and filter about 3000 miles ago. I've had this going on for about 1000. Started about the same time I changed tunes to PHP. They haven't been able to find anything in the tuning yet that could be causing this or if it is just making it show up now.
View 14 Replies
Last night I bought 2000 F250, 346k on it... Crew cab short bed 4x4 with ranch hand bumpers like I wanted .... Headed back home (Miami FL ~1100mi) and covered about 200 miles @70-75mph before i ran into few problems ....
First off, while cruising I noticed slight hesitation in the throttle, with loss of speed regardless of pedal pressure, noticeable on inclines. It would go away on downhill and get smooth response again and pick up speed. This went on for about 40 miles.
Then I noticed heater blower stop blowing hot and start blowing cold, without me changing any settings. At the same moment, I noticed temp gauge move up and I hit next exit offramp to check what's up. During right turn at the end of off ramp truck stalled. Pulled to the shoulder, and popped hood.
Noticed empty degass/overflow bottle. Carefully opened lid and water gushed up to the top. When all pressure slowly released, water pulled down and emptied the bottle. Both upper and lower radiator hoses are empty. Engine oil has no traces of water tho. There were no leaks under the truck. I then tried to fire up the truck to get me to the gas station 1/8th mile away.
No crank in Park. WTS comes on and goes off. Cranks in Neutral, RPMs come up some, oil pressure shoots up to normal running position, but won't fire. Tried a while then gave up as not to kill starter and batteries completely.
Fuel pump works 20 sec then shuts off. There is fuel in bowl. I covered 140 miles since last full fill up, so not fuel pickup issue I don't think.
Summary
Have crank
Have RPM
Have oil pressure
Have fuel
Have (had) batteries, now not so hot
It's cold out ....
View 14 Replies
I drive a new to me 2005 F350, he has a 2001 F350. While we were talking he said he didn't think his pickup had the power it should have. He pulls a 5th wheel camper that weighs around 8000 pounds fully loaded. He said it takes a couple of miles to get to 55 mph, and it is hard to hold the speed. It doesn't have the power it did when he first got it last year. He was told that a diesel is slow getting started. He rode with me in mine, when I dropped it about half throttle to pass a slow car he said he could tell mine had way more power.
His check engine light is not on, it starts good both when hot and when cold. It runs smooth, no miss as far as I can tell listening to it. What are some common issues that could cause this? He did just change the oil and fuel filters, not sure about the air filter. He said the power loss came before he serviced the engine, and did not improve after the fuel filter change. Where to start? He was also told to check the filter inside of his fuel tank, so he is getting ready to drop his tank.
View 14 Replies
When I'm driving at highway speed and press the accelerator after coasting a bit, the engine stumbles then picks up and accelerates. The fuel bowl assembly is brand new as of 5 months ago, and I drained of any water last month when I changed oil. Truck is stock with 350k miles.
Apart from this issue, it runs well and idles smoothly. Injectors are healthy per a buzz test a powerstroke mechanic performed last year. What could cause the stumble off idle?
View 11 Replies
Truck (02' , 7.3 ) has check engine light and since I'm on vacation don't have access to my Autoenginuity diagnostic software, so looks like I'll have to go a auto parts outlet to get the code read.
But.... before I do I wanted to get some input from y'all. Basically what happens is the idle goes up while in gear and when I put it in neutral, idle goes back down to normal. In addition I noticed (yesterday) somewhat of a lope or stumble at idle while in gear. No stalling and no effect to fuel mileage.
Since I'm away and away from my tools I'm somewhat limited. Certainly once I get the code I'll know more.
View 5 Replies
What is the speed you have to be driving before the airbag will pop off in the event of a frontal collision? just wondering.
View 5 Replies
2001 ford excursion 7.3l diesel.
So I tried to go to work today but the truck said no. it started out fine then out of no where it felt as if someone slammed on the back brakes engine still revved up like normal just didn't want to go. speed dropped to 20mph then i heard a clunk. after that it was fine until it hit 20 mph again. it did the same thing again.
So I got mad at it thinking the trans went out gave it the beans and it shifts into all gears but did not feel like it had power. i did pull over and check the fluid looked a little orange. when got back in the truck i did notice the od off light blinking?? drove the truck home was shifting fine but hear this awesome sounded like a hand grenade rattling around underneath. when i got home notice fluid coming from the bell housing(out of the bottom).
View 14 Replies
Ok I have had this noise going on for about 1 week before transmission went out. I just built the trans and its still there.
I had a mishap years back with front end hub bearings so I replaced with New Timken Bearings. Well that wasn't it but at least I know where I
stand with those. It starts making a noise when slowing down about 3-5 seconds before coming to a stop. I thought maybe the carrier bearing in
driveshaft?
Pinion bearing in rear diff? I need to service the parking brakes on rear so I may pull it down and go through it.
View 6 Replies
I am having trouble with my 1999 F350 Ford Powerstroke, Looses power but the motor never quits and also starts up fine, will set and run and warm up on the coldest morningIdles fine, It will hold back sometimes and not increase speed. I can take it out today and it may be fine and tomorrow can't run 2 miles. I was thinking CPS but after reading information I am not sure. What may be causing this issue. I just put a High Pressure oil pump on it could this have anything to do with it. Was not having a problem before the pump was changed. The pickup has 190,000 on it actual miles.
View 7 Replies
I have recently picked up an older F350 2WD 7.3 DRW Lariat. the price was right higher miles but hey it is a 7.3, overall in very good shape.
So the issue at hand is the truck runs great most of the time and puttering around at city speeds you would never know there is any issue;
Get the truck out on the highway set the cruse at 70 to 72 and if you hit a rise in the road or other reason to slightly accelerate the truck chugs and bucks. For lack of a better description it goes chug chug chug, if you accelerate harder to downshift it goes away or if you back off the throttle it goes away. This happens with cruse on or off, a steady foot on the pedal will cause this as well.
I have also noticed that when you let off the throttle the sound the truck makes de-fueling is just very different and "off" sounding . Not sure how to describe it but it sounds funky ... clearly not right when compared to other 7.3 or my 6.0 truck.
What I have done, :
1. Had the truck scanned with an AE and a snap-on scanner both show no codes ran injector tests no contribution errors, not even in # 8.
2. Changed fuel filter
3. Changed Oil and Filters ( tried both full synthetic Rotella and Dino oil looking for a difference )
4. Cleaned out the fuel filter housing just in case.
5. Confirmed injector O-Rings are not leaking
This feels like a fuel issue, my next thought was start looking at fuel pressure under load at speed to see if there was a drop when this is happening ?
Is there a way to test fuel pumps in this truck ? Maybe a clogged pick-up screen ? Where do I start looking next ? I have reasonable mechanical skills but don't know this motor very well, this doesn't seem like a CPS issue..
View 7 Replies
I recently (1month ago) rebuilt my entire front end. The only things that were not replaced are track bar, steering box, front driveshaft, and sway bar bushings. I'm having the same issues that I had before the rebuild. It just feels like the front is is on basketballs. Hopping and vibrating at any speed or rpm. On a smooth road or on the highway it feels like I'm hitting bumps that aren't there.
View 14 Replies
I have a 1999 F250 4-wheel drive with a 6-speed tranny. The tranny is several old but has only around 100k on a rebuild. Three times recently it has stuck in 6th gear (overdrive) and I had to get really rough with the stick to get to come out. Afterwards the stick felt "thick" for a while and eventually everything seems to go back to normal. Not for sure but it may have started after pulling a heavy load, around 16k, which is not unusual for the truck. Other than the times it stuck and shortly after, the tranny seems perfect.
View 5 Replies
I just noticed today while driving to lunch today that at lower speed and tons I can here an intermittent hissing sound. But as I speed up and build boost it goes away. Not sure what could be causing this sound. it sounds like it could be some sort of pressure leak or exhaust leak I have no clue...
View 12 Replies
The noise is somewhere between a tin rattle and a bearing grinding heard most when braking but constant under say 10 mph. We have not been able to pinpoint where exactly it is coming from but I believe it is front drivers side.(but really could be anywhere) it is not dependent on rpm, nor gear or clutch engagement, Nor hubs engaged or disengaged.
The drives side front hub, rear hubs' bearings(races and seals) have been replaced. I have the passenger side front hub to do as well, just haven't gotten to it yet and it doesn't seem bad. we are all stumped on what it is. It seems to relate to the rotating assembly though as it seems to change with speed. it almost seems like tire rub, but there is no scaring or marks of any sort anywhere for it.
Vehicle is a e99 f250 short bed ext cab. open diff if it makes any difference. My next thought after the hub is pinion bearing? Could it be something to do with abs? say the truck is 4 wheel abs but the fronts are disconnected (trying to figure out if it is 4wabs as it appears to have connectors, but the original hubs did not have the hole for the sensors. no abs light comes on, but that could be a bad bulb too)
What we have found is hubs locked or unlocked, 4wd engaged or disengaged, and happens at right around 16 mph, braking, accelerating, clutch in or out, in gear or in neutral. All 4 corners have new bearings. We have found 2 things, 1 is the track bar bushings are shot (don't think this is the source of the noise but could be wrong and i will be replacing those..once I have money in again.. 2 the passenger side leaf spring when wacked with your hand makes a different sound than the drivers side.( could be a matter of different loads, but figured worth noting)
There are 2 noises, the first is the noise we hear, the second is one that i found when doing the noise reduction (loud meaty tires you cant hear the noise in the audio without reduction) I think that that was one of the hubs, or maybe the brakes, I am unsure, but it happens at different locations in the video.
Audio : [URL] ....
View 11 Replies
Ok just needing info, am I about to have any major issues as my truck is making a loud rhythmic squeaking noise when I move at any speed that is lower then what the speedometer will register (5mph or less) should I be concerned about the noise? It only occurred when I'm at very slow parking lot speeds....
View 8 Replies
I went to check out a '03 7.3 SD the other day. It didn't seem to have a lot of surge when I accelerated to freeway speeds. Kind of lazy feeling. Didn't smoke out the back though. It did have a front end clunking sound going over the parking lot speed bumps. I opened the oil fill cap while it was idling and it blew a plume of vapor/oil about 9' high like a steam engine puffing. Held my hand over it and got a oil wet palm after just a few seconds. I'm hesitant to drop any $$ on it.
View 6 Replies
