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Discussion Starter #1
So I recently purchased a 2000 F250 super duty 7.3 power stroke with 246k. I actually traded my 96 wrangler, 02 ram 2500 and a car hauling trailer for it. I now have one vehicle and it’s not running the way it should. So the first time this happened, the same day that we made the trade, I ran it through the car wash and all of a sudden about a quarter mile later it started losing power and falling on his face. Eventually got it back home and the only codes it was showing for a P 1000 and a P603. I turned it back to stock and it still wouldn’t run very well and had less and less power. Three days later I was waking up Monday morning to take it to a diesel mechanic and it acted as if it had never been symptomatic and it ran absolutely perfect. I took it anyway. The guy ran a few scans and told me I had a great truck so I left. Four days later on Thursday, I was driving to an appointment in the rain and about 10 miles into my drive it started doing The same exact thing. I drove at the rest of the way and then drove it the other 17 miles back home. It’s been three days now and I’ve been looking for anything I can, harnesses are tight, I pulled the PCM and IDM out of the fender wheel well and inspected for water, cleaned them and coded them with dielectric grease and still nothing. I took the cps out and inspected it, fine. I took it out again and it started throwing a code saying exhaust back pressure sensor low, I can’t remember the exact number. But it feels like there’s a miss, and when I get it up to about 40 mph and let off the Excelerator, all of a sudden the service engine light will come on momentarily and then go back off. It only does that when you can feel the back pressure from the exhaust deceleration. I don’t have another vehicle to drive and I’m literally lost as to what to do now. before we made the trade, the guy had new pigtails put on the harnesses at the Ford dealership. It also has doorman head gaskets, so I know that is not the problem as well. There are a lot of new things that have been replaced on this truck, it’s a long list, and I’m fairly certain it’s something electrical, but I just cannot seem to find it. I also have a leak in my roof that drips out of the overhead display, but I don’t see that being a problem unless someone else knows some thing I don’t. Please anyone, I need some help!
 

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The bottom left side of the windshield is known to leak. It can drip water down on the GEM and fuse panel. Usually causes other gremlins, but it fits with the rain. The other water induced illness is certain CPS models don’t play well with the wipers.


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Yeah, believe me, I have read a million forums and watched a bunch of YouTube videos trying to figure it out. I pulled everything apart and there seemed to be no water leaks anywhere. It seems to be throwing different codes at different times. I had a 1316 code which I’ve come to understand doesn’t really tell you much because it’s sort of generic. A P1000 code is typical when you Run any kind of new tune, as is the P603. It’s making me believe that there is something somewhere grounded out, but I have looked at all the areas that seem to be common for problems in the rain. When I say that I have unplugged everything I can find to check for water and reseal it with dielectric grease, I mean LOL. One thing that I did notice though and the only place I have not checked, there is apparently a water leak in my roof because I saw a couple drops of water come down from my overhead display. I’m getting ready to tackle that as we speak
 

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What RT said about the CPS and wipers. I had one that would die when the wipers were on, but run well when they weren't being used. The fix was to put chokes on the wiper motor wires. But I eventually got rid of that CPS as it was causing other issues as well.
I'd recommend you try a new Ford CPS. It's the grey one (F7TZ-12K073-B) that replaced the black one. They're relatively cheap and could be the fix for your problems.
 

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Discussion Starter #5
So it does have a brand new Ford Motorcraft CPS on it. It’s not the windshield wipers either, like I said, I’ve been through every forum and every video I can find on the Internet and I have stripped everything down on this truck and can’t seem to find the problem. It’s saying some thing about back pressure low sensoSo it does have a brand new Ford Motorcraft CPS on it. It’s not the windshield wipers either, like I said, I’ve been through every forum and every video I can find on the Internet and I have stripped everything down on this truck and can’t seem to find the problem. It’s saying some thing about back pressure Sensor low and when I let off the gas at about 45 the check engine light pops on and the truck feels like it’s missing an injector
 

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Check this thread out. I didn't have water that I could find, but when I opened up the fuse block it had water shorting across traces internally.

 

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I have had to track down a similar issue with a different vehicle.

When its back to running good then spray a small part of the vehicle with a hose. Only do a small section each day so the previous area has sufficient time to dry.

I would also track down that leak in the overhead. I have a truck that had a hole in the roof for a radio antenna and when the antenna was removed, a rubber grommet was installed. Maybe you have something similar?

Or maybe you have the cab running lights?
 
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