So I thought it was water in the fuel....drained my water seperator, replaced the fuel filter (and air filter just in case), no change. Been through 3 tanks like this. Then I thought it may be worse, so I put in a bottle of Lucas, still nothing...plugged up OBD, no engine codes, nothing looks out of the ordinary.

Sometimes its fine, but most times it sputters & shakes.

Not sure if it is related, but I noticed that sometimes the lights will get brighter/dimmer as the truck sits and idles.

What are the other possible issues?

Thanks!!

Josh
2003 3500 Diesel

 

That brightening / dimming is the grid heater cycling on an off. The CTD doesn't have glow plugs, it uses the grid heater that is under the intake horn to pre-heat the air going to the cylinders. It's perfectly normal.

As for the shaking.... how long have you had the truck and how many miles are on it?

 

I bought the truck in 2004 with 11k miles on it. It now has 110k.

Thanks!

 

Are you noticing an white smoke? Other than a little puff from the exhaust when you start it up when it's cold.

How does it feel, power wise?

3 things that might be causing an erratic idle like that.

1 - You have a clogged / stuck injector.
2 - The FCA (fuel control actuator) on the CP3 is stuck / sticking.
3 - The crank damper is shot.

Numbers 1 & 2 you'd need to bring it into the dealer and have them hook the DRBIII to it and do an injector isolation test (shut down each injector individually) and a cylinder contribution test. Usually costs approx $65, depending on the labor rates in your area.

Number 3 is something you can check. Go under the truck and looke where the harmonic damper is on the crank pulley. There is a rubber isolator ring between the hub and the weighted damper. If there are cracks or missing chunks of rubber from the damper, it's shot. Also, there are 2 alignment marks on the damper. One on the hub and one on the damper. If those marks are more than 1/16" out of alignment, the damper is shot.

Those would be the first 3 things I'd look at.

 

I have a 2000 Dodge Intrepid that did the same thing. At a red light the car would idle and shake about every 2 seconds. After checking almost everything that could cause the problem i found the solution. I had a bad ignition coil. i replaced it and the car runs better than b4 with no shakes .

 

Unfortunately, that has nothing to do with a diesel.