Intermittent Idle Variation

[wgood]

My 03 has 181,000K miles and it is a great truck. We have been full-time RVers for most of the last 6 years pulling a 37' fifth wheel. Last year we bought a house in SouthWest Texas so we have begun to settle down somewhat. However we still plan to travel with our fifth wheel several months of the year.



Over the last few thousand miles I have noticed that the engine idles inconsistently at times. After the engine is well warmed up, I may pull up to a stoplight, and it may begin to idle at around 1100 instead of 750. If I engage the clutch enough to move the truck slightly and then stop again it will likely drop back to 750 or 800. Then, maybe at the next light it will be OK - OR maybe not. It happens maybe 30 percent of the time.



I'm thinking I may need a Fuel Control Actuator. Any other ideas? How much trouble is it to hange the FCA?



Thanks for your help.



Bill

 

[Wingate]

If its a CR engine, if all the other normal maintenance is good ( filters) you might try the FCA. I have heard that if an FCA is acting up, you can run a quart of 2 cycle engine oil in the fuel tank, if it quits acting up, then its most likely the FCA.

I have heard and read this many times, but have never actually done it myself on a CR Cummins... But, it won't hurt anything to try and 2 stroke oil is a great lubricant for the CR fuel system.

The FCA is easy to change, a couple of torx screws and a wire connector.

 

[SierraRam]

I would replace the FCA first, easy to DIY. My 03 started idling funny, had some injector knock and stumbling. Changed the FCA and solved the problem.

 

[hitchjnj]

I havehad the same problem with my '03, after awhile every once in a while it would shoot up to 2800RPM. Changed the FCA and it was good for two weeks and then started again. Changed the ECM next and it was good for three weeks and now is doing the same thing. The fuel system has been diagnosed with no problems. I guess all thats left is the APPS. Any thoughts?



'03 3500 DRW SLT 184000 miles

 

[cerberusiam]

That is a known glitch with the early manual trucks. Its the ECU trying to anticipate clutch engagement and it loses its mind is the best description. There was a flash for it that had limited success.



Might be worth trying as is the FCA. It does weird stuff when it gets sticky.

 

[wgood]

Thanks to everyone for your responses. I guess I'll get an FCA from Genos and see if it helps.



Bill