Just bought the EX on Friday. During the trip home, I had the engine die on me a few times, within a very small time frame. The previous owner did not drive the EX that much so I figured there might be some cob webs. A CEL came on and AutoZones scanner gave me P0720.

What do?

 

This code points to the OSS or Output Shaft Speed Sensor.

This sensor is located on the tail of the transmission and from the sound of things, need to be changed.

 

Well, I did some searching and the speed sensor can sometimes be a precurser for other problems. I'm taking the EX in for the A/C on Monday. I think I'll have them scan with a better scanner and see if there is anything else going on. If that is the only thing wrong I'll probably get the part from Rockauto and change it myself.

 

Searching some more shows that a bad COP or coil pack could be the culprit. How do I test these things?

 

Since I just bought this thing I am thinking about just getting all new COPs and plugs. Maybe I'll do this and replace the OSS at the same time. Hopefully this will take care of things.

 

What year is your Excursion?

If you're ever in the Sioux Falls area let me know. I have Auto Enginuity on my laptop and you are more than welcome to stop buy and we'll run a scan as well as some engine diagnostics. I'm not as familiar with the V10 as the 7.3L but will be happy to help out.

 

Is AE a common thing for even smaller shops to have? Thanks for the invite. We only travel that way once a year enroute to ND. Maybe later this summer we can have a meet-up.

 

AutoEnginuity is a great diagnostic tool that many on this forum and others have. It will allow you to see trouble codes, run diagnostic checks, datalog engine performance and adjust the speedometer for different tire sizes. It ussually pays for itself in the short term.

Here is a link for more info:

Riffraff Diesel: AutoEnginuity Total Ford Enhanced Bundle

 

Well I kinda stopped caring about this problem because the CEL went out. I attributed it to the fact that the person I bought it from wasn't driving it and it just sit for a while.

Today I was in the carwash and the EX died on me three times. Then the CEL came back on. Can the Output Shaft Speed Sensor cause the EX to die? This wasn't addressed in previous posts.

 

I am not sure if others have had the same problem that I had, but mine was one with the bad COP causing the problem. I was actually able to reproduce it by swapping the old COP back onto the same cylinder. The COP's are very easy to swap out. If I were or have to do it all over again I think that I will by 2 brand new MC COP's and swap them out two at a time to narrow it down. Keep the 2 brand new ones as the "standard" by moving them to the next two spark plugs each time till I find the problem COP's. Once I new which two then I may try to narrow it to which one. If you are not as cheap as me then you could do 5 "standards" at a time, but that would take away a lot of the fun. LOL.

There is a plug on the fender well on the drivers side that goes down to the transmission. You can unplug it and verify that the VSS and OSS are not the problem. My mechanic unplugged it and monitored the engine at idle in gear. The software he was using (my have been AE) reported that he was going 123 mph just sitting there. It was actually jumping around at the time. He said anywhere from something like 35 mph up to the 123 mph for a high. At that point he told me it was either a grounding issue or a bad electronic component. I went through all the grounds and cleaned them up. Then I went through checking for AC voltage ripple. No problem there. That was when I went back to the COP's.... and BINGO!

Hope that helps.

 

I would have it looked into with ae or a shops scan tool to better narrow down what it could be. Of course 260,000 miles it could more than likely be a cop or 2 I have a few good cop's if you want them Just pm me I have a few more things if You want and oh of course free to a fellow ex owner!

 

Well, I put all new COPs and spark plugs in today. Only had a 15 minute test drive, but it seemed better already. No sputtering in the low RPM range, and it hasn't died yet.