'03 with extremely rough high idle

[Cattletrkr]

Talkin' about dad's '03 CTD w/ auto, not the truck in my sig.

When it's cold enough for the automatic high idle to engage, the high idle is extremely rough. It sounds/feels like someone is playing with the go-pedal. I would classify it as a "chug". That exactly what it does. Chug, Chug, Chug, Chug, Chug, Chug, Chug, Chug, Chug, until someone deactivates the high idle. Even the regular idle is a little choppy at times.

FCA was replaced a year or so ago (problem has been around for a while) and it maybe helped a little, hard to tell.

It does smoke a little when the engine is cold. Smells like unburned fuel.

It's been to the dealer and they just gave a good old fashioned shoulder shrug.

 

[rbattelle]

Sorry, Cattle, I'm at a loss on this one. Check fuel filter (possibly plugged due to cold temperatures and #2 fuel)?

Any performance enhancements on his truck?

Ryan

 

[dunderkofler]

Is it cold enough to be doing the three cylinder idle?

 

[Cattletrkr]

He has a LED indicator for the fuel pres. Filter was replaced recently. This has been an ongoing problem with many filter changes spread throughout.

He has a Banks 6 gun on now. Truck came with it. We took that out last winter and put in an EZ, which is now out. Problem exists regardless of which chip is in or without any of them.

How cold does it have to be for 3 cyl to kick in? I haven't heard of the trucks doing that other than with a Smarty.

 

[GRoutzahn]

Sorry I don't have anything to suggest but, I have an 03 SO Auto w/ a Banks and this winter it has begun to do the exact same thing you're talking about. During high idle it runs rough, only smokes a little bit, and smells like fuel. No smoke otherwise.

 

[Cattletrkr]

I'm not a big banks fan, but just so we don't start blaming the Banks... When this started this winter the Banks was completely unhooked. as was the EZ. We hooked the Banks back up to do a little mileage testing.

 

[dunderkofler]

I think 3 cyl kicks in at 15F. No experience with it myself because it never gets that cold here.

 

[WKruger]

Try kicking the idle up w/ the cruse control. If it doesn't chug, then it's doing the 3 cyl. high idle.

 

[rbattelle]

3rd gen trucks always run on 6 cylinders - they never kick down to 3. Only 2nd gen trucks do that.

Maybe rail pressure relief valve?

Ryan

 

[Cattletrkr]

3rd gen trucks always run on 6 cylinders - they never kick down to 3. Only 2nd gen trucks do that.

Kinda what I thought.

Maybe rail pressure relief valve?

That would cause a problem at idle?

 

[rbattelle]

That would cause a problem at idle?

Yeah, probably not at low pressure. I have a tendency to blame the relief valve when performance boxes have been used.



Ryan