Help Needed Guess what? Replacing the CPS didn't help!

Friis

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Hi all.

I'll be referring to this old thread: http://www.superdutydiesel.com/forums/99-7-3l-powerstroke-engine-drivetrain/18143-momentary-power-loss-what-my-truck-telling-me.html

Years back, I wrote:
"Over the past 500 miles or so I've had a strange experience with my stock Y2K F-250 4 times. When driving 40-50 mph and letting go of the throttle the "emission system" light comes on and power is gone. The engine is in idle as the truck is decelerating and there is no response whatsoever from the throttle. After about 5 seconds the light disappears and power is back. On two occasions the trans shifted violently from 1st to 2nd and back to 1st and 2nd again and repeated this 4 or 5 times. After that everything was completely normal. On the last two occasions the were no hard shiftings.
After the first time I thought it to be some kind of glitch in the computer system and thought nothing more of it, but now I think my truck is trying to tell me something... Every dipstick checks out fine. No burnt smell or low oil. And the ride is completely normal between theese strange events.

Please help. Thanks."

I was told the CPS was probably bad and ordered a new one. Well I finally replaced the CPS, after living with this strange problem for more than two years. It was annoying but not so much that I bothered to act on it. But recently it got slightly worse, so I made the change. And guess what... It didn't work!! I still have the problem and it is completely random. Some trips of more than 50 miles won't see the problem, and at other times i happens 3 times during the first mile...!

So now I'm back to square one... Any ideas will be greatly appreciated!!
 

JLDickmon

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Hi all.

I'll be referring to this old thread: http://www.superdutydiesel.com/forums/99-7-3l-powerstroke-engine-drivetrain/18143-momentary-power-loss-what-my-truck-telling-me.html

Years back, I wrote:
"Over the past 500 miles or so I've had a strange experience with my stock Y2K F-250 4 times. When driving 40-50 mph and letting go of the throttle the "emission system" light comes on and power is gone. The engine is in idle as the truck is decelerating and there is no response whatsoever from the throttle. After about 5 seconds the light disappears and power is back. On two occasions the trans shifted violently from 1st to 2nd and back to 1st and 2nd again and repeated this 4 or 5 times. After that everything was completely normal. On the last two occasions the were no hard shiftings.
After the first time I thought it to be some kind of glitch in the computer system and thought nothing more of it, but now I think my truck is trying to tell me something... Every dipstick checks out fine. No burnt smell or low oil. And the ride is completely normal between theese strange events.

Please help. Thanks."

I was told the CPS was probably bad and ordered a new one. Well I finally replaced the CPS, after living with this strange problem for more than two years. It was annoying but not so much that I bothered to act on it. But recently it got slightly worse, so I made the change. And guess what... It didn't work!! I still have the problem and it is completely random. Some trips of more than 50 miles won't see the problem, and at other times i happens 3 times during the first mile...!

So now I'm back to square one... Any ideas will be greatly appreciated!!

anybody handy have a scan tool with data logging capability?
 

DaveBen

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I don't have any take on tuners. I don't run one, so it is up to you. Others here do run them and will surely add something to this.

Dave :)
 

dpantazis

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the tuner may not data log like you want to.

have you checked the valve cover electrical harness connections?

does your truck have a chip on it? are you SURE? go through the PCM de-install and reinstall per the wiki.

how are your batteries?
 

dpantazis

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TikiWiki : Selectable/flip chip install

since you got the truck used, it might be worthwhile to double check to make sure that there is no chip on the PCM. or if there was, that the installer removed it properly and reinstalled the wiring harnesses correctly. its a long shot but will take all but 15 minutes and a beer or two to check.

i would also check the valve cover harnesses. it does not explain all the symptoms you describe, but you never know.

there was a part fix for the clips to keep them from coming apart. the roadside fix was grinding down the edge and wedging a quarter in the connector to jam it tight. i am sure that you can improvise and find a kroner or two that will work the same.the coin thickness is about 1.67 mm in the middle and 1.75 at the rim. here is a descent write up:

50 cent mod - Ford Truck Enthusiasts Forums

proper Ford part #2C3Z-14A163-AB. List for about $15?
 

BJS

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Just so I'm not making expensive recommendations that aren't the real answer, just a few clarifications on what it's doing.

1)We do not have "emissions system" lights on US trucks so I'm hoping and guessing that this is roughly equivalent to our Check Engine light unless they were required to install additional emissions equipment to meet your local emissions standards as US standard trucks have no computer controlled or monitored emissions equipment.
2) When the truck acts up does the engine die and need to be restarted? or just kick to idle?

If it is kicking to idle and/or giving less fuel than "normal" for throttle position then I would suspect the electronic pedal assembly. They are a couple hundred dollar part and fail somewhat regularly. An errant reading from the throttle position sensor and idle validation switch (one piece on SD trucks) will trigger a computer fault.

When a CPS fails the engine will go dead requiring you to turn the key to restart the engine.
 

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