Rough Idle on Startup

[AWeaver]

Hey guys, I just bought an 07 with the 5. 9 in it. It has right at 78,000 miles on it and is bone stock. When I first start it in the morning it seems to have a rough idle. Once it warms up it purrs like a kitten. It only does it when its cold though. Its not real bad or anything but it is noticeable... to me anyway. It wasnt bad enough for me to notice when I test drove it so its obviously not too bad, but after having it a few weeks this is what I have observed. Am I just paranoid or should I have something to worry about?



BTW I just changed the oil/filter and the fuel filter yesterday. Also the previous owner did install a 2 micron HUGE fuel filter/water separator on the frame rail between the stock filter and the tank. He said he got some bad fuel and had to replace two injectors b/c of it. He said the others checked out fine. Should I have the others checked??? Thanks in advance and the truck in my sig is for sale if anyone is interested. I can send pics... shes a great truck but I dont need two!! Thanks in advance, Aaron.

 

[steved]

Most likely a weak/failing injector solenoid...

 

[AWeaver]

Does that mean im going to have to replace the whole injector? (sorry if thats a dumb question but im new to the common rail) and how do I find out if that is the culprit for sure? My truck still has a warranty but I am very leary of our dodge stealership here in Granbury, TX.

 

[TCDiesel]

No. . But their is No part # for the solenoid, and it needs to remove by someone with the injector holding tool and clocked correctly.

 

[steved]

It takes special equipment to find it... if it were me, I would probably buy a new set of injectors (complete set) and start over again. You know a couple were already replaced, and bad fuel doesn't selectively affect injectors... been there, done that.

 

[AWeaver]

thanks steved! I've been thinking that in the back of my mind and just needed to hear it from someone else. If he had a whole tank of bad fuel he most likely ran the whole thing through the engine thus affecting every injector in it. I guess only two were bad enough to warrant replacing at the time. Do either of you guys have a suggestion on a best bang for your buck set of injectors? Cant really afford f1's which is what I would like. I plan on having guages installed first and probably a smarty for electronics. Thanks again.

 

[JJPage]

Aaron, my 03 runs rather rough when I start it when cold also, always has since new. Once it warms up it smooths right out, hate to see you spend all that money on a set of injectors when possibly not needed.



Valvoline makes a very good injector cleaner, I believe a quart treats up to 250 gallons of diesel. Try adding some of this product to your fuel, and run it, once it is mixed well with the fuel, the "at rest" time on the injectors(when not running), this product will loosen carbon/debris if any is present.



I have a couple of M11 Cummins motors on gensets, that quite often run at partial load. They were starting to run fairly rough, put a load bank on them to clean them up and started using the Valvoline, they are performing great.



If you are really concerned, you could take it to Cummins and have them do a cylinder contribution test, however at this point, I wouldn't borrow trouble.

 

[AWeaver]

Point taken. I did actually buy some lucas at oreileys two days ago and put about a third of the bottle in a full tank of fuel (the quart sized bottle not the gallon size). I will let you know the results. I will try the valvoline also.



My dad also told me the same thing about his 04 and his 07. He said both of his previous trucks did the same and he owned both since new. His 07 was the 6. 7 and not the 5. 9 btw. I guess maybe im just paranoid since the guy I bought the truck from told me that about the injectors. Its getting great fuel mileage though... about 19 mpg mixed highway and town driving. Ill let it ride for a while and see if it gets any worse. I dont have the $$$ for a set of injectors right now anyway. Thanks to everyone for their input!

 

[Blakers]

My truck goes into spells where it will idle rough for a while - almost like it's stumbling a little, though not a dead miss. Drive it down the road a mile and it's ok. I've done injector cleaner, changed filters, etc. without much change. And it's only intermittent and not temperature related.

I go from gas well to gas well all day, so my truck idles a lot, and doesn't get a good workout often. That may have something to do with it. Or it could be always be something in my Van Aaken box failing??

Blake

 

[AWeaver]

Blakers... just re-read your post researching my problem. It hasnt gotten any better or worse. I guess its just a symptom of the common rail. Just curious... I am in the oil/gas industry and was wondering if you see any excalibur water trucks diriving around up there. Im from texas and used to work for them. I am actually looking into getting in to a pumper position for quicksilver resources. I assume thats probably what you are doing. I came from wireline. PM me if you would like to chat. Ive got questions about both. Aaron.

 

[Wingate]

It wouldnt surpise me if its just the cold engine fueling causing the engine to run a little different.

Many modern diesels have a "cold engine" stragedy that alters fuel duration and timing in an effort to help warm the engine up quicker..... In some engines/years they even selectively misfire some cylinders to put more load on others, thus generating more heat.

I would pull an oil sample to check for fuel and if there are no other symptoms (CEL's, crankcase full of fuel, excessive smoke. etc. . ) , I'd wait on the results.

More than likely, IF you take it to a shop for troubleshooting, they are gonna convince you that you need new injectors..... whether you really need them or not...

 

[AWeaver]

you could be right... ive noticed when its cold enough outside for the intake heater to come on it does NOT idle rough. It only does it when the intake heater does NOT come on before you start the engine. definitely weird. I dont know if you read the above threads but my truck has had some injectors replaced due to bad fuel as well. Ill keep an eye on it. Thanks for the input!

 

[Jordi]

mine was doing the same thing for the past six months, started getting worse last couple of weeks, no codes, no smoke, ran perfect when warm. Replaced Fuel Control Actuator on weekend ($119 on ebay) completely fixed it. Hope that helps.

 

[Blakers]

Where is the Fuel Control Actuator located on the engine? Thanks.

mine was doing the same thing for the past six months, started getting worse last couple of weeks, no codes, no smoke, ran perfect when warm. Replaced Fuel Control Actuator on weekend ($119 on ebay) completely fixed it. Hope that helps.

 

[Jordi]

on the back of the cp3 (injector pump) driver side of engine, one electrical connection, 3 t25 bolts, cummins part#4932457, make sure to torque bolts 30 inch pounds once around then 62 inch pounds again within 2 minutes as per factory manual. Jordi

always try the cheap sh%t first, too many alarmists on these sites

 

[AWeaver]

good advice... look in your genos catalogs. They sell the FCA for $115. Part #4932457. might be worth a shot. genosgarage.com baby ! Ill start there and post my results...

 

[HerbW]

You can buy injector solenoids on Ebay now and change out yourself rather quickly. Even new BOSCH ones! Look up some of my posting on injector solenoids. I can find the bad one and change in about 20 minutes. You can to if you have the right stuff with you. I carry a new solenoid with me in case I go to limp mode again. I would help another TDR or Dodge buddy if FORD! (Found On Road Dead!). A repair for less than $100!

 

[Mathes308]

Mine runs a tad rough off and on, think I'm also just paranoid.
Get the HPCR jitters!

 

[HerbW]

Does the FCA just unbolt and the new one go in easy?

 

[JBallou]

Yes. Just make sure that you are using the proper torx bit. I think T-27.