Good Morning,

I have a 2002 F250 SD V10 4x4, that just started to randomly misfire [does not matter if the vehicle is in motion or in park]. I scanned the OBDII and found pending code P0720 (Output Speed Sensor). The CEL, O/D light, nor the ABS light illuminate. The speedometer functions normally.

This occurred Saturday after we got 12-18" of snow. I cleaned out the driveway, took a short drive (~ miles) & parked the truck (no symptoms). Later we went to 2 stores and then on the way home, the misfire started. The next day the misfire continues.

I have been searching & come up with the same posts that say the issue is not the OSS. It's usually a bad COP or bad wiring @ the OSS. The symptoms are not the same as when I had a COP go bad (only misfired under load between 1500 & 2500 rpm).

Does anyone have any experience with this situation?

Personal issues: My truck does not fit in my garage, it's dark (and ususally below 30 F) before I can get to look at it in the evening. Also, we are supposed to get another foot of snow tomorrow night.

Thank you in advance!

 

The last time I had a rough running engine with a speed sensor failure, it was with our '01 Durango with 4.7L V8. I don't recall the code exactly but it turned out to be the engine speed sensor. I replaced the camshaft position sensor first thinking that was it and then the engine speed sensor on the side of the block. Might be something similar with the V10.

 

Mine seems to have a similar problem as yours, Snow, melting snow and salt everywhere . Today my truck was sitting still idling and it sounded like it had a big cam in it. It seemed to quit but tonight my wife drove it and said it was missing and running like crap. I cant get mine checked out until next week so will have to wait and see.

 

Jade and Kart,

If it doesn't turn out to be the code you got then you might try the below suggestion.

I'd recommend starting with making sure there is no moisture in the spark tunnels/holes. (It's a very common problem with V8 & V10s)

Remove the coils and boots one at a time checking for moisture in the plug tunnels. Normally if you look at the boots after removed from the plugs you can see moisture if it's present,,, but sometimes you can't. So a visual inspection of the tunnels/plug holes is important.
You can easly see into some of the tunnels (plug holes) but some are impossible to see into.

Recommend:
If you happen to have a compressor with a blower tip? Blow each tunnel out after boot is removed.

If you don't have a compressor I would recommend borrowing one or purchasing a cheapo. I'm sure you can figure out another way to get them cleaned/dried out but a compressor really is the easiest/best way.

NOTE:
When re-installing the boots add some dielectric grease to the boot tips and top seal portion. This helps to keep the moisture out.


Rick...

 

Thanks , I'll need to check that out once this crazy snow stops.

 

Sheesh,,,

Where's your sense of adventure? Get out there and take care of your Truck.

Even one moist plug/boot can cause the engine to run very rough. If it's just a very small amount of moisture it can cause intermittent roughness.

Rick...

 

I agree with Rick, I had an old nissan truck that would run like crap when it rained, turned out it was a cracked spark plug boot allowing water to get in.

 

When I pulled into the garage to change the sensors (OSS & VSS) it shut down 3 times, resulting in a full code P0720. I changed the sensors & the amount of mis-fire reduced. I'm wondering if I may have gotten a tank of bad gas? I did fill up before the last storm. I put some B-12 in the tank last night (it's a cleaner & drygas), so we'll see if that helps.

I looked at the intake area (I did not pull any COPs), and it appears dry. I'm going to try to run it tomorrow, if I have work (60 mile round trip) and I'll put Sunoco Ultra in it.

Last time I rotated the tires, the end of my air hose came apart (that was fun ) and I need to repair it.

Thanks for the advice.

 

COP # 4 crapped out.

Same one I replaced in 2006.

 

So you got it sorted out then? No more P0720 code and misfire?


Rick...

 

When I actually pick up the part & install it, the issue will go away.

Last night, the COP went completely dead....


Thanks for all the help!

Anybody know if the Duralast Ignition Coils have a Lifetime Warranty, like some of their other stuff?

 

I got a chance this past weekend to check out problem and I had 2 codes P0171 and p0174 Lean bank 1 &2 . After doing some research here on FTE I was amazed to be pointed in the right direction because these codes from what I found out could be alot of different things. Probably just lucky but one of the threads I located pointed me in the direction of a vacuum leak normaly caused by a defective elbow on the vacuum hose from the pcv valve to the underside of the throttle body, sure enough it was split wide open. Thanks to everyone here on FTE what a great site with great information from great members....

 

The other thing I would check is to make sure you have no vacuum leaks. You need to follow from the canister on and trace each vacuum hose and check each little joint fitting and each elbow fitting and the connection points those hoses end up at.

I see you got it solved, looks like my info was a little late but glad to see ya got it fixed, amazing how something so small could cause problems so big