1999 V10 Superduty 4wd with 200K (lots could be wrong I guess). Headed out today, and the truck started losing power. Ran OK with throttle barely cracked, but try to accelerate, and it would shift down correctly, but start slowing down. OD light started flashing, but would go off on restart, and it only happened twice. I suspect it was an issue with not being able to shift properly due to the loss of power. The CEL finally came on, but I haven't had it checked yet. I found lots of problems I've had either didn't show a code, or caused a code on an unrelated item. At any rate, I can floor it in neutral, and it will rev up to about 4K, and start dropping. It is missing some too, but not enough to warrant the loss of power. Only thing different is I recently just recharged my K & N. I did a "quick clean" of the MAF on the road, but no change. Funny thing, the longer you drive, the worse it gets, eventually to the point of about 30mph is as fast as you can go. It would slow down so much it would kick off the cruise control. You can stop, shut it off, fire it back up, and it is much better, although not right. Seems to be idling fine. Just thought I'd run it by you guys (most of whom I consider experts). Finding a mechanic these days that can diagnose something rather than shotgunning parts at it is very difficult. Last time I tried this forum, after going to Ford, and with no error codes, I was introduced to the IAC valve, which solved my problem. Any ideas where to start would be appreciated. I'll try to get a code tomorrow. Sorry for the long post, just wanted to be as detailed as possible.

P.S. I do have on O2 sensor not working, but it has been that way for a while, and been running fine( I know, I need to get it fixed).

Again, thanks for the help in the past, and any thoughts now will be appreciated immensly!!

 

a bad o2 will cause loss of power and make it run rough. get that fixed and report back.

 

I had the same thing with my v10 it turned out to be a couple coil packs.

 

Ok, got up this morning to go get the codes pulled, and the CEL was off. Got the codes pulled, and unfortunately it didn't point to any specific sensors(that's what you guys are for...).

1131:
Lack of bank 1 02 transitions-Lean

ECM detected bank 1 O2 at it's lean limit (which I don't know if it means the sensor was trying to lean out a rich mixture, or that it was detecting a lean mixture at it's limit)

1151:
Lack of O2 switches-Bank 2 sensor 1 (whichever that is)

ECM could not adjust fuel trim because of a rich or lean condition.

They could not tell me which O2 sensor wasn't working from the codes, so I didn't not get one at this time. The only way I knew one wasn't working was from a previous issue about a month ago, and one of the sensors was at 0 while the engine was running, but the other was constantly adjusting. Unfortunately I don't remember what bank or position it was.

 

Update:

Being able to drive it, and not just read a description of the problem, I always felt it was starving for fuel, or had a CAT problem. With that in mind, while having the codes pulled, I got a fuel filter. With the fuel deliver not being monitered, I guess if it was low, it would cause otherwise good sensors to return error codes for something they couldn't overcome. At any rate, the filter was beyond nasty. Looked like coffee coming out of the inlet side. Seems to have cured the problem, but won't know for sure till I hook up the boat. Yes, I still need to replace the O2 sensor. I can't wait either, considering how much fun I had talking my truck into giving up it's old fuel filter.

Thanks for the help. I consider this forum, and other's like it, priceless. Full of very knowledgable people.

Thanks again, and I may be back if this doesn't cure it. Whether it does or not, it definitely needed a new one.

 

At 200k, replace both upstream O2 sensors. OEM Motorcraft sensors are $55 each at rockauto.com. If you keep running bad sensors, you WILL screw up the cats. They cost a lot more than O2 sensors. If your fuel filter was that nasty, I'd throw some Techron or BG44K in the fuel.

 

Same here i hav e same exact problem. . please any help!!!!!!

 

Can you get the codes read and post them?

 

You have the same year truck with the same engine?

 

I dint have the codes yet but i can get them today . i was driving down the highway and i can feel the truck starting to jerk slightly while pressing accelrator. It will then not go over 40 , 60 mph. Will keep slowing down so much i tried turning it off and starting it up again . tht helps out for a couple mins . it will run good for 1 or 2 minutes and willd do the s ame thing over and over again.

 

Sounds like your cats are plugged.

I would check your exhaust back pressure.

 

I was following these forums looking for a fix for my 99 f250 superduty v10. I had similar power loss. I had gotten low on fuel and it started sputtering and missing. It wouldn't pull out on a steep street and had to back down into another street. I could get up to speed on the level, but couldn't romp down on the pedal for any power whatsoever. I checked out all the codes on google, but found no fix. I found egr sensor port broken, but it didn't fix the problem. I changed the fuel filter with no improvement. Coils and plugs were fine. I decided to check the fuses in the power distribution box under the hood on the driver's side. (It is printed right on the box.) I found a yellow 20 amp mini fuse in the #7 spot (numbered in the lid) blown. I identified it on the net as generator. Changed that fuse and it fixed the issue. It may not be your problem, but it can't hurt to check. I only wish I had checked them first.

 

12 years later, I doubt the thread starter still has the truck. If he does, I would bet that it's fixed.

 

I just got a F-450 with a V10 Triton in it. The trucks been sitting for a couple years. Changed all fluids, filters, and plugs. Starts right up and runs good idle. I would drive it and for 15 minutes has good power. After it warms up, and I go to step on throttle, it sputters. However, I can get up the RPM to the moon while idling if I press gas pedal slowly…any thoughts? New MAP sensor and new throttle position sensor.

 

What year?