So I did the AC ripple test and got a reading of .079 volts on the AC side of my meter. I found that was within the spec of less than .1 volts, but got a surprise when my battery voltage before I started the Ex was only 12.09 volts. I fired it up and it read a perfect 14.65 volts. I decided to clean up the wiring at the battery and replace the battery connectors. I removed the old wiring from the off road lights I removed a year ago. I took it for a drive for about 30 min and got no codes and it ran perfectly. I hope my issue was just something in the stupid old wiring.
2001 Excursion V10 4x4 Auto 151,000 miles 285/75/16 BFG AT's, stock rims
2nd trans cooler and spin on filter, converted to electric fan (increased MPG by 1.1mpg towing) Trans temp gauge, Volt gauge, and Vacuum gauge mounted in 3 gauge driver pillar pod, Custom Safari Rack, Full size spare on the rack, Mag light at driver door, LED interior lights.
1978 Bronco 460, NP435, BW1345, Dana 44HD/ Dana 60, 40's "project"
First, I would like to thank everyone for the postings on this issues. It has help me out more than you know, thank you. I have a 2002 excursion v10 and it has 168,000 miles on it. So i thought i would change the plugs and not the coils yet, change them and then 3 days later i put some gas in my truck and it started. The stalling out in gear, rough idle, no power 0-45 mph and then the check engine light came on. I thought that i had bad gas, drove it out and put more gas in from a different station no change. Went to the shop and the mechanic says it putting out a 700, 720 code for the trans. But he said that he does a lot of work on ford trucks ( it was a truck and rv shop) and that they are bad for putting out the wrong codes. So we went for a test drive with the scanner and under load driving, it was telling us that the coils were mis firing and which ones.And he said that it could still be the trans too, but not likely. So i took it to the dealer, and they saw the same codes and told me it was the oss sensor and wanted $410 to fix. So i hoped on the internet to read about it and found this site, and told the service guy at the dealer could it be bad coils and he said NO. The codes would say if it is the coils, "he said". He said that the oss is the reason that the truck is running that way, because it is bad and telling the computor to starve the truck for fuel to save the motor. Do i listen to someone just trying to make money or people who are having the same issues and fixed it. So i bought new coils and put them on, and the problem went away. I was told not to get the cheap ones, because they do not last long and they only had a 90 day warranty. The one`s i got cost $57 with a lifetime warranty. You guys save me a lot of headaches, Thanks
AdditionalMy 2000 X 6.8L 190K starts and runs smooth, but stalls and gives CEL when put in D or R. My searches indicates OSS. Will cleaning it help? What size is the bolt holding it to top of tail shaft? I don't have a OBDII and don't want to have it towed yet
Last edited by Limoguy; 07-07-2013 at 02:24 PM.
Reason: Additional info
OK, so how did you determine it is the OSS? When the truck isn't moving the OSS isn't reading anything. You CANNOT set a code for the OSS with the truck standing still.
The ONLY way to know what's wrong is to get the codes read. If you don't want to read the codes I can make you a list of parts. You buy them and install them. Just let me know when it stops doing that and you can call it fixed. I expect you'll run into the problem part in the first or second thousand dollars.
__________________ Mark Former Ford Automatic Transmission Engineer 1988 - 2007
“The good thing about science is that it's true whether or not you believe in it.” ― Neil deGrasse Tyson
I will have to confirm also the failed cops will trip the P700 and P702 code for the OSS.
I replaced all 10 coils and plugs shortly after putting in the banks tube headers as things were not running right.
I order the oem ford cops, and bought plugs from the local ford dealer.
This was during the summer so I was riding my bicycle to work and did not put a lot of miles on the truck. 3 months (about 2000 miles) and the codes started to come back up. I ended up taking it in to the dealer as I had misplaced me AE scanner. They found 2 bad cops. Sent in my order details to the place I bought them online, and had 2 new cops fedex in 2 days under warranty, no questions.
Went on vacation, about 3000 miles return trip and was running nice and strong. 1 month after, ended up sputtering out the same codes. Took it to dealer and they found 1 more coil out. Very frustrating as they only have about 9000 miles and are oem ford cops. Get the replacement sent in again fedex on their coin, replaced said cop and still running good.
Moral of story, it is more than probably the cop shorting out and causing all sorts of miss codes, unless you look for misfires you will be only replacing unnecessary parts with the OSS sensor on the tranny.
2002 Excursion, 4x4, V-10, XLT, RS9000 shocks, true trac diff, 08 alum diff cover, interior light delete, 08 power fold/xtend mirrors, KM2 tires, 5 Star tuned, front cryo powerslots with hawk pads, XRF ball joints. 50" front mounted LED bar, 10" reverse light LED bar. Banks stainless long tube headers and exhaust kit., front seat heaters.
2011 Expedition, Ltd Max, 4x4. 30" LED light bar, flip key fob, 9 passenger, more to come.
Well after months of this intermittent issue, I finally found the problem and it's something that I called the dealer and they said that was the first they have seen. So, bought it with 145000 miles on it and it had this prob already. Being new to me and reading this site, I wanted to do new coils, batt, plugs and all the fluids which all are done. So first month would get the OSS code on and off weekly.so I would go under hood check everything out. Then for the past 3 weeks no codes running fine. Sunday I wash X open hood dust engine and visual inspection, everything good. Take off next morning back to same BS code. Today, open hood, look around and it dawned on me, I have a short in my hood light wire. I caught it by as I closed the hood I saw at last second that the hood wiring was bending in between the hood and body instead of going in engine bay. At first I thought it couldn't be it because the light goes out before you close the hood so the power would not be going to the light but the hood light switch is a mercury gravity switch at the base of light so those wires always have power. Man, glad it's over and hope this one can help someone out as well. Thanks all for your great knowledge
Randomly changing parts is a very expensive way to try and fix this. Some diagnosis would be a good thing.
Start with electrically checking the wiring harness. This involves a meter. If no problem is found you'll need an oscilloscope for the next step.
With the oscilloscope look at the waveform in the alternator output. If an alternator diode has failed the output will have an AC component on top of the DC output. If this is getting a bit technical, it may be worthwhile to pay someone that has the right equipment and knowledge to do this for you. A very good independent shop would be my first choice. Some Ford dealers can do this, too. All of them should be able to, but only some can.
I realize this is old thread but I never reported back (and never thanked Mark). Thanks Mark, electrically checked Bad grounds was the problem. Fixed and no issues now for months.
I found an old Ford tSB about the ground issues. With a code read you can see the vss thinks the vehicle is going about 30 mph even though you are stopped or going slow. It actually caused the trans to go into second gear I think and it then reported the trans code (I think but I am certainly no expert).
There was a Ford ground harness I couldn't track down, so I just drilled and tapped a new ground bolt and grounded them all. This was a v10 motor home chassis. Zero problems since.
My bad ground was a painted negative battery terminal clamp that Wal-Mart installed when they replaced my battery. The - post to chassis wire was making contact with a painted portion of the clamp and not passing enough current. I replaced it with an unpainted lead terminal clamp and it cured the PO720.
I was blowing a lot of coils before the battery replacement. I attribute that to the horrible condition of the stock clamps. They has deteriorated to almost nothing due to corrosion.
2001 2WD X V-10, 3.73 (now 4.30) LSD
Michelin M/S 2, Load Range E
Roadmaster Active Suspension
185,000 miles, rebuilt transmission at 95,000
Prodigy, Draw-Tite Dual Cam
Jayco 308 FBS
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