Guys, I have an 03 7.3 auto, the other day after a small, shallow water crossing, about hub depth. The truck started to idle up and down of it's own accord whilst in netural. It would go down to about 500rpm (nearly stalling) and then up to about 1100. If you floored the throttle it would hesitate and then rev up, if you held it above about 1500 it had good throttle response, but could not get it to drive. I lifted the hood and sprayed WD40 every where and waited about 5 min to let things dry out, all the while the truck was running up and down of it's own accord. I managed to get running and over the next ten min it went back to running smooth. However over the last week or so it has been doing similar, but not so severe, like when you put the A/C on in a small car, how the revs drop and then rise.
I have Microchips tuner installed and have tried to check for any codes but none come up, would the tuner pick up a CPS problem, do these problems sound like that could be the cause. The truck has about 70000m on it.

 

I'm new to the PSD but had a CPS going bad and it would stall out and refire while driving down the road or just stall at a red light. When this happened I got no codes with my reader. Don't know if this helps but stay tuned someone smarter than I will chime in.

 

Mick, you might have a different problem. I first noticed my CPS problem in the rain, but some of your problems are unfamiliar. Mine went on for a couple of months. At first, I'd be underway and the engine would give a quick "seize" out of the blue.....scared hell out of me the first couple of times. The "check engine" light would SOMETIMES come on after it happened (if the "seize" was violent enough). It then got into the habit of shutting off a few times while at idle at a stop light (with vehicle still in drive) or while making a fairly hard slow/stop and turn (like into a parking lot somewhere).....At the very end (just before I changed the CPS...and NOW it runs perfectly...for the past 15000 miles), it shut off, and when I restarted the engine, it would stutter and start on the way from 5mph to 40mph and had to feather my way back to highway speed. Keep in mind, using the A/C, etc. NEVER had any effect on the engine....and nor did pulling a heavy load, etc.......I never had problems with the engine just revving up and down while underway........

Steve

 

I think it's the CPS. Replacing it and no resolution just provides him with a spare if it doesn't fix it and rules the CPS out.

Steve: Never retreat, call it an attack in another direction.

Also, do you know why plan B always sucks? Because if it was worth a damn it would have been plan A.

 

Someone else is obviously familiar with "Murphy's Rules of Combat"...(haha).....And your quote sounds suspiciously like Chesty Puller (bow your heads)......

But yes, go ahead and change the CPS and if it works, great problem solved....if not, you've got a $105.00 spare.......

 

Sound Like The Iac Sensor Is Faulty And Reading The Actuation Pressure For The Heui Pump Or Your Pump Is Starting To Cavitate Change Oil And Try If Problem Persists Need To Read Logged Codes In The Ecm ..

 

Listen to herman2001.
There's been a lot of stalling, driveablility problems that have been solved by a simple oil change with the PSD.
The water crossing can be purely coincidental.