Rough idle

[boomchadda]

When im cruisin on the highway 60mph or higher for a while and then get off and come to a stop and let it idle the trucks idle will be rough? dont know why? never in city with stop and go traffic only when on highway when the engine is revving for a while??? I read somewhere that this could be because i have done a couple of FCA mods. Is this true? Any ideas?

 

[rbattelle]

I read somewhere that this could be because i have done a couple of FCA mods. Is this true?

That's where I'd point the finger. Return the system to stock and see if the problem goes away.



Ryan

 

[p-Bar]

Seems a bad FCA will cause idle issues as Ryan says. Someone said to buy it from cummins it's a lot cheaper.

 

[231jasonS]

I have the same exact symptom. My FCA is stock and my truck has done it from day 1.

 

[rbattelle]

Maybe we should first define "rough". These engines don't idle like a gasser - they shake quite a bit more.

Ryan

 

[231jasonS]

Well mine has a strange stumble at idle. It feels like a cly or two are dropped for a few seconds then recovers. It will do this for 10-15 seconds and only after an extended cruise, not stop and go traffic.

 

[boomchadda]

LOL trust me I know what my trucks normal idle is.

 

[JCockerill]

my 06 has a once and a while rough idle, it feels the same. only dose it once in a while. strange, feels like a miss too. i have to figure out the conditions it dose it in. usually cold i belive.

 

[steved]

Well mine has a strange stumble at idle. It feels like a cly or two are dropped for a few seconds then recovers. It will do this for 10-15 seconds and only after an extended cruise, not stop and go traffic.

Most likely FCA... classic symptoms. If you watch the tach, it will cycle up and down a few times until it levels off, it will slowly get worse.



Mine did it as well... replacing the FCA cured it, but after about 50k its back again.

 

[steved]

A rough idle (like its missing) is different from a cycling RPM at idle...

A rough idle can be caused by poor fuel or injectors... the cycling RPM is typically the FCA.

 

[JCockerill]

what is FCA?

 

[steved]

what is FCA?

Fuel Control Actuator... controls the fuel pressure to the rail...

 

[HullD]

Any new news on this?

My 03 calif. does this all the time.

It seems worse on hotter days.

 

[ACerf]

I am having basically the same problem. Changed the FCA and it didn't correct the problem! A year ago I had the transfer pump replaced under waranty. It started to idle rough in neutral and park. I took to a good cummins mechanic, and he thought it was the FCA also, changed it and it is still doing it. After doing testing he has concluded that the transfer pump is bad again. Cummins/Dodge told him that I had to much carbon buildup in the engine from excessive idle time. I am running some Centane Booster to see if that might help clear up the problem, I doubt it will correct it completely. He told me that the in-tank transfer pump kits have not been very good. He has ordered a pump separate from a kit. We will see if this corrects the problem.



By the way, there is a TSB about a rough idle caused by a bad FCA. Check it out at your local dealer.

 

[JCockerill]

has this been a problem in the newer models such as the 06?

 

[231jasonS]

It is in mine, except its only after a long cruise (like on freeway) not just after stop and go traffic. And it only lasts for about 15-30 seconds then it clears up.