I took my 2002 Excursion to the LM dealer the other day. It has the 7.3 PSD. I've had a problem with it lurching at speed mainly around town (1500-2000 RPM). Doesn't so it all the time. I told the dealer that it could be the CPS, but it is not throwing a code and of course when they took it out it didn't show the lurching symptoms. He said that he cannot change the CPS unless it is throwing the code or symptom. It has 70000 miles on it and warranty expired in June. I have them checking some leaks with a dye so I want to get all the warranty work done on one ticket.

Quastion is how often will the CPS throw a code and has anyone had a dealer replace one under warranty without a code?

 

No the CPS doesn't always set a code. Unless the dealer can retrieve a code or duplicate the symptoms, they probably won't replace it either (unless you pay for it).

My suggestion is this: get on Ebay and buy a CPS for $50. Keep it in the glove box of your truck along with a socket wrench, 10 mm socket, and extension. That way when it does fail, you can be back up and running in minutes.

 

I just happen to be borroing a Preadator programer, and when my CPS when out my enginge check light came on and when I read the codes it did throw a code. can't remember what the #'s were, but I cleared the code and luckily made it to my friends shop that was much warmer than outside (10 deg).
this is my first CPS issue so will it thow a code every time, not sure. Just my .02

 

P0340, P0341, and P0344 are the CPS codes

On a Cali Truck it will throw a code if the error occurs once in a sigle drive cycle, on Federal trucks the error must occur 3 times in a single drive cycle to set a code.

So if you have an intermittant CPS and it only errors twice before you key off then no code will be set.

Additionall if it is not setting a code the dealer or anyone with a capable scan tool can monitor the CPS Error State and tell if it is going bad even without a code.

 

Just to let you know, I talked to the tech that worked on my Excursion. He owns a 7.3 and knows it inside and out. We took it out several times and got it to stumble/miss once. He told me that it is not the CPS, but recommended keeping one in the glove box, which I will do. He had it hooked up to the computer and nothing showed up.

He said that with the new low sulfur fuel, it lacks the lubricity of the old fuel. He thinks the injectors are sticking and suggested putting an additive in the fuel which will boost Cetane and lubricity. I will let you know what happens......

 

Man I wish this wivestale would DIE.
ULSD is required to meet the same lubricity standard as LSD, the old stuff.

How can he be so sure it's not the CPS? As has been stated it will NOT throw a code unless the problem occurs 3 times in a row.

What I suggest is taking the CPS he told you to put in the glovebox, and installing it. If it doesn't fix it, put the one you removed in the glovebox and look elsewhere. I have a feeling though, that it will fix it.

Also, your tech should have checked fuel pressure, among other diagnostic test, instead of just blaming it on the new fuel.