Ok guys, here is my problem in detail. I have an 04 F250 4x4 king ranch with a 6.8 V10.

When I first bought this truck it had a problem of stalling out at stops. You could sometimes hold the brake and gas and push your way through it but it would sputter for a second and try to die and then it was fine once you got going. The OD light would flash, check engine light would come on and it would throw a P0720 code for the OSS. I did some researching and I pulled the sensor in the pumpkin before that because I read that could cause the same problem, so I cleaned it and put it back but it didn't solve the issue. Then found that an K&N air filter can often times clog the MAF and cause the issue so I pulled my air filter and sure enough it was a K&N, I swapped it with a normal filter and sprayed some MAF cleaner and its been running like a top for months... until now.

It started again, gradually at first. It would die when I started to back the truck at a very low speed to load my 4 wheeler. I fired it up and it was good again for a couple more weeks, then I went to hook to a horse trailer and I was having to back up a hill to get to it, and it just kept dying, OD light would flash, check engine light came on. I was in a bind so I just tried wiping off the MAF with a rag, that didn't help, my girlfriend was using the truck and said it kept dying whenever she stopped. I got it home and cleaned the MAF with cleaner really well but the problem persisted. I went ahead and changed my oil, spark plugs(gaped at .052-.054), replaced the IAC(which looked like it had been installed once before so I am guessing someone tried it and when it didn't fix the problem they returned it) and changed the fuel filter. I drove it around and it ran fine, drove it to work and it ran fine, my girlfriend took it for about 15 minutes to run an errand for me and it was fine until she got back in the parking lot and liked to never got it parked again it stalled so much.

So I went back to the drawing board and read that it is rarely the OSS that is the problem but that often times the issue is a bad coil pack. I don't have a scanner nor do I know how the heck to use one. I plan on going out of town at the end of the week and the truck has 194k miles on it so rather then take it to a shop and try to find out which COP was bad I just decided to replace all of them(I know, I know, you should never just start replacing parts). I only had time to replace 5 of them, I took the truck out and again it dove fine for an hour, went through traffic OK. It sat for an hour and when I left it started to die again, I could drop it in neutral and it would fire back up and as long as I gave it just a hair of throttle it stayed running fine, take my foot off the fuel and in a minute it would die again. After I drove for a bit it was fine again. Now I know the problem may yet be in the remaining 5 COP that I must change tonight but in case it is not I wanted to know if anyone had any input on this.

I've read the problem can come from a bad ground, so I took every ground point that I could find under the hood and I cleaned the connectors and took the paint off at the connection site just for good measure. The problem persists.

I've read that sometimes a diode can go out on the alternator and cause this problem, I did use my amp meter and I'm checking out at 13 volts while running. I'm not the best with meters so I'm not sure how else to check the diode?

I've also read that taking it to a dealership is hit or miss for them diagnosing the problem, sometimes they find the issue, sometimes they just change the OSS. The only mechanic I trust closed his shop and is now service manager of the Dodge dealership. I'm thinking since this seems to be a common problem that maybe ford might have more knowledge of it then dodge but I trust the dodge dealership more because of who is over it. Either way I know it will sit in a dealership for awhile before it ever gets looked at and if they have to chase any electrical problems then that starts racking up $$ fast.

So what kind of input can you guys give me on this, what am I missing? I've thought about replacing the MAF since cleaning it the first time solved the problem. When it did this the first time I still had my 01 F250(it never gave me problems like this) and so I took the MAF off of it and swapped them and sure enough it fixed my problem so I switched them back after I cleaned the MAF and like I said it's been running fine until recently. I'd rather not throw money at this by replacing parts and hoping for the best. I've also read about tracing the harness that runs from the sensor on the pumpkin to the OSS and on. That harness runs through all kinds of stuff so I'm dreading that but it will also be a next step. I haven't pulled the OSS because its in a very awkward position on my truck.

I may be jumping the gun but I figured I would start the ball rolling by asking now in case changing the other 5 COP doesn't do the trick, and considering the success rate I have had so far I don't have high hopes...

I will keep you guys posted. Thank you in advance

 

P0720 is the output shaft speed sensor on the rear on top of the transmission not the one on top one rear diff. Most likely though with the rough running it's not the sensor. Your voltage sounds a bit low if it's just 13 it should be between 13.5-14.2 running especially if your checking at the battery with a meter. I think and don't quote me on this but if the rectifier is bad when you check the voltage you check for a/c voltage instead of d/c and if you have any a/c then it's bad. Mines done something similar a few times never stalled just ran a bit rough and and thrown the p0720 won't do it long enough for me to find the issue though. Keep us updated if you get it solved I think your on the right track that it's a bad coil unfortunately replacing them all is a pricey solution but if you don't have a scanner that reads mode 6 data or ids or the like then you can just buy one or two coils and move it till you find the bad one good news is it shouldn't take 10 minutes to do the other 5.

 

Is there any update on this, I have a 2003 f250 v10 that is doing the same exact things a close mechanic of mine was telling me it is a sensor on the transmission and the only way to get to it is pull the trans. Any help would be greatly appreciated.

 

There is no sensor in the transmission that requires the transmission to be removed to replace the sensor. I recommend finding a mechanic that knows what he's doing. That one either doesn't know, or is looking to pad the bill.

 

 

Bad coil packs will not cause a flashing OD light.

 

 

I just wanted to echo Mike's problem and solution. I have a 2002 F250 with a 5.4 L motor. I was experiencing similar problems with the P0720 code and the overdrive light flashing, and the truck would intermitantly die at an idle. Unfortunately I spent $1,500 trying to get it diagnosed at the Ford dealer before finding this post. Like he mentioned the Ford dealer was going down all the wrong paths trying to diagnose and fix this problem. They replaced the speed sensor twice as well as the PCM. Next they wanted to tear into the transmission and that's when I decided to look into it myself. After reading this post I purchased some Motorcraft coils online and installed them myself and the problem was immediately corrected. After talking with the Ford mechanic, as well as another mechanic, neither of them could figure out why the coil would have been causing that code to come on. But it does. If you have similar problems, don't hesitate trying to replace the coils as a fix.

 

Sorry to revive an old dead thread, but since we are closing in on Halloween, maybe appropriate? I am currently experiencing this issue (2003 F250SD V10) and wondering if anyone has any new experience or expertise with this problem? I'll start with the coil replacement as I feel a slight miss. I can tell you this stalling out is no fun when trying to retrieve my boat from the boat ramp. Mechanic couldn't find any reason for 0720 code.

 

My bad Heintzee, I have a bad habit of intending to update on what the fix was and then getting busy and forgetting. It's been so long ago I don't even remember 100%. I'm fairly certain replacing the coil packs solved my problem though.

If I remember right, you can test the coils to see which one misfired but, once you have one going bad I'd just replace them all . I'm out of town but if replacing the coils doesn't fix the issue let me know an I'll try to go through my service book an see what other parts I changed back then. I'm driving the truck still so I fixed that issue at least lol

 

Thanks for the quick response, I figure I'll start there, this problem has been so frustrating to what has been an otherwise problem free truck for me 16 years. I'll keep you advised.

 

My truck was doing this. It would occasionally die at stoplights and throw the Trans and check engine lights. It would up being the alternator. It produced enough juice at speed, but when you'd sit at a light idling the output would drop. May or may not be your problem, but a couple of minutes with a multimeter is a hell of a lot cheaper that just flinging parts at it. Also worth noting - Autozone tested my alternator and said it was fine. It was not. I ended up replacing it even though they disagreed. That solved the problem, but I bought their piece of **** duralast alternator. 2 years later, same problem. If you do find out it's the alternator spend the money on a decent one.

 

Thank you '01V10, I will check the alternator first. Fortunately I have another truck to drive currently as I need to find the time to work on the 250.

 

Fwiw mine was throwing the output shaft speed sensor code too. Which apparently could be anything from a coil to blinker fluid.

 

My 07 F250 was also stalling at idle for about 9 months, tried a few things to correct it, but nothing worked. Then the alternator lost its will to live. (Of course it waits until the temp is below zero first). I never did get a battery warning light. My first sign of trouble was my radio telling me it was shutting down due to low voltage. If you ever see that warning, you have about 5 miles before everything dies.

Replacing the alternator aslo fixed the stalling issue.

Low voltage or power with alernator noise will do strange things to computer controlled vehicles.