Rough Idle Problem!

[ACerf]

I have a 03' 5. 9 that came from California (that sucks). The engine idles rough in Neutral and Park. I have had two dealers look at the problem, the last one decided after extensive testing that the fuel pump mounted FCA was bad. I had to agree, but after driving it a few miles I stopped and let it idle. In park it was still running rough. What was funny, it wasn't idling as rough in neutral?? The other thing I noticed is that when you apply the brake it reduces the roughness. This is driving me crazy, and I think the mechanic is running out of ideas.

What I am looking for is some input of possiblities. The mechanic told me that there is a second FCA near the rear of the engine on the same side has the pump mounted one. Is this true??

Thank for any help I can get!

 

[daytripper63]

Get rid of the Edge EZ and I bet the rough idle goes away...



I had mine stacked with a TST and when I removed the Edge the rough idle went away, my guess is the injectors dont like increased fuel pressure.

 

[ACerf]

Get rid of the Edge EZ and I bet the rough idle goes away...



I had mine stacked with a TST and when I removed the Edge the rough idle went away, my guess is the injectors dont like increased fuel pressure.

I wish that was that easy. I have not been using the Edge EZ for the last week the dealer has been trying to find the problem. It doesn't seem to matter if the Edge is hooked up or not. That was the first think I thought of too. I have been running the Edge for almost as long as I have owned the truck for 90,000 miles. I would think if the Edge were the problem it would have started causing problem a long time ago. Also I am running the edge at the lowest setting.

I have heard that the Edge stacked, like you did will cause problems.

Thanks for the help

 

[RDyson]

There is only one FCA and it is mounted on the CP3 injection pump. If your mechanic is telling you that there is another one, I'd find another mechanic.



I had a similar problem with mine, and changed the FCA and it took care of it. You can get a new FCA from Cummins for about $100. They are alot more expensive at the dealer.



Can you read your rail pressure with the x-monitor? What pressure are you running at idle and normal cruising? If it is low, it could be an injector problem.



Randy

 

[SierraRam]

I had a 03 SO and the FCA was the problem, change it any it will run like new.

 

[Missouri Mule]

There is a FCA on the back of the CP3 (injector pump) and it can cause rough idling. Never read of one being on the fuel pump.

I have read that cracked injector housings can cause problems. Seems to me rough idle was one.

 

[ACerf]

There is only one FCA and it is mounted on the CP3 injection pump. If your mechanic is telling you that there is another one, I'd find another mechanic.



I had a similar problem with mine, and changed the FCA and it took care of it. You can get a new FCA from Cummins for about $100. They are alot more expensive at the dealer.



Can you read your rail pressure with the x-monitor? What pressure are you running at idle and normal cruising? If it is low, it could be an injector problem.



Randy

The truck is still under warranty, and as I said previously the FCA did not correct the problem. The mechanic that has been working on it is one of the best in the area, and he said there was a second FCA. Who am I to argue with a certified Cummins mechanic! When I go back in this week I will have him point it out to me. The Injectors and pump are working okay. ECM is upto date with software changes. The FCA replacement is a TSB, or TC as they call them now. To answer your question; no I can not read rail pressure with my x-monitor.

I stand corrected; you are correct the FCA is on the injector pump not the fuel pump. I just wrote this wrong.

 

[AllianceDiesel]

there is only one fca on the cp3 trust me I'm dodge/cummins cert. there must not be very many mechanics in your area, lol. Whats a TC? Its called a Technical Service Bulletin (TSB)

 

[SierraRam]

There is a CR pressure relief valve but not two FCA's. If you replaced the FCA and it did not fix the problem you are more that likely looking at injector issues. Have you crtified mechanic test them, suprised he can't figure out the problem?

 

[JHardwick]

It's an injector problem ... ... ..... F1 cured mine.

 

[RDyson]

The truck is still under warranty, and as I said previously the FCA did not correct the problem. The mechanic that has been working on it is one of the best in the area, and he said there was a second FCA. Who am I to argue with a certified Cummins mechanic! When I go back in this week I will have him point it out to me. The Injectors and pump are working okay. ECM is upto date with software changes. The FCA replacement is a TSB, or TC as they call them now. To answer your question; no I can not read rail pressure with my x-monitor.

I stand corrected; you are correct the FCA is on the injector pump not the fuel pump. I just wrote this wrong.

Sorry, I didn't catch that you had already changed the FCA. And on your certified mechanic, when he can't find the other FCA, that may tell you something.

I'd not heard that the FCA replacement was a TSB. But it's covered under the 5yr/100k warranty. Your mechanic should be able to read the rail pressure on his scanner. That should help with a diagnosis.

I was starting to have lower rail pressure and a longer crank time on mine. I have since replaced the injectors with some F1's and now it's running great.



Hope you get it figured out soon.



Randy

 

[AllianceDiesel]

there is a tsb 14-004-05 for surging at idle and they are saying to replace the efc which I never heard of the must mean the FCA.



Your mechanic needs to run an injector kill test when the truck is idleing rough to see which injector when cut out causes the rough idle to lessen. are he needs to drive it and when he can hear injector knock under load usually around 1700rpms cut the injectors out and see which one stops the knocking. He should know how to do this if he is diesel cert. I knew how to do that a week after I started and I wasn't even cert. then.

 

[ACerf]

there is only one fca on the cp3 trust me I'm dodge/cummins cert. there must not be very many mechanics in your area, lol. Whats a TC? Its called a Technical Service Bulletin (TSB)

The new term for TSB is now TC. I was told this is a recent change by Cummins. If you are a certified mechanic you would know about STAR for technical help. I believe that the term TC came from them. I will be going to the dealer Tuesday morining I will ask him about the other FCA.

 

[ACerf]

He has already done all of the checks on the injectors and injector pump. No problems, no codes. He put a load on the injectors and did the cut out of each one. All checked out okay.

 

[AllianceDiesel]

its a tsb and will always be a tsb, it has nothing to do with cummins, every automaker that I know of calls them a tsb. and yes I know what star online is, and I have probably spent more time talking to the star center than 90% of techs because thats the only way you could get parts was to review your findings with the cummins group at star center.



you find the evidence that calls it a tc and I will take back my statement, If I knew how to post a screen shot I could show you right on chryslers website where it says service bullitens/recalls.

 

[ACerf]

its a tsb and will always be a tsb, it has nothing to do with cummins, every automaker that I know of calls them a tsb. and yes I know what star online is, and I have probably spent more time talking to the star center than 90% of techs because thats the only way you could get parts was to review your findings with the cummins group at star center.



you find the evidence that calls it a tc and I will take back my statement, If I knew how to post a screen shot I could show you right on chryslers website where it says service bullitens/recalls.

Don't get your dander up! I am only telling you what the tech told me.



All right here is the puzzle; Since the FCA was changed the truck idle is okay in Neutral. However, if it is Park it starts to idle rough, but not as bad as it did before changing the FCA. If you apply the brake pedal when it starts to idle rough in Park, it smooths out for the most part. Why?

 

[daytripper63]

Here's one for you... I bought a Smarty and am currently only running level 2 ( cause it smokes like a frt train any higher) but it smoothed out my idle better than its ever been, so last night I returned the smarty back to stock and the semi rough idle is back.

 

[JHardwick]

My vote still goes on injectors.

 

[RDyson]

Applying the brake may put a little load on the engine through the hydroboost system. This will add a little more fuel which may smooth the engine.



When you are in neutral, do you have your foot on the brake to keep it from rolling? May explain the smoother idle in neutral.



I agree with JHardwick--injectors.



Randy

 

[wcjp]

Locally, there was a truck that required a second new FCA. The first new FCA was bad out of the box. I might have missed it, was the filter changed and lift pump checked for pressure and flow?