Ruff Idle

[MCervinka]

I have a new ' 05 CTD and feel like the idle gets ruff. You can see the mirrors rattle at idle. It also sound like the rpms are high, around 800 @ idle. In some ways it sound like it might be missing. This happens off and on and seems to be happening more often. This will happen in the morning, hottest part of the day afternoon, or evening.



Can anyone give me a clue on what this could be?



2005 4x4 quadcab 6 speed no mods. 2700 miles.

 

[CLAYTON]

Is there any white smoke from your exhaust?

 

[MCervinka]

No smoke at all.

 

[JCleary]

I've had that problem with a bad load of fuel. Perhaps try changing your fuel filter and fill up at a high-volume well known brand station. It may solve your problem.

 

[MCervinka]

We have a few places to pick from. What stations do you think offer the best diesel. Side note; I just seen our prices went up now @ $3. 15 gal northern California. Unreal. I think they are trying to slow down the sales of diesels.



Shell

Mobil

Arco

Chevron

 

[JCleary]

We have a few places to pick from. What stations do you think offer the best diesel. Side note; I just seen our prices went up now @ $3. 15 gal northern California. Unreal. I think they are trying to slow down the sales of diesels.



Shell

Mobil

Arco

Chevron

In my experience (20k miles or so):



I've found that very few Arco stations carry diesel. I wouldn't buy it there anyway. A chemical engineer was telling me about how they keep costs down, I wouldn't use their gas or diesel.



I've filled up twice at Shell stations. Neither time was I happy. I had the symptoms you describe.



Couldn't tell you about Mobil.



I fuel at Chevron pretty much exclusively now, but I've had a bad tank from them, too.



The best thing I think would be to pick a station you know sells a good quantity of diesel. Preferably a station with newer tanks. Perhaps you will cure your problem.



I'm going to install a 3 micron FASS filter system. Hopefully that will cut down on my truck's finicky taste.

 

[rbattelle]

Bear in mind the diesel will vibrate and rattle A LOT more at idle than any gas engine. Sometimes mine will rattle the rear view slightly at idle, and I can always feel the engine vibrating through my seat at idle. I consider it very normal. You say it "sounds like" it's running at 800 RPM... what does the tach say?



-Ryan

 

[DPKetchum]

Let it idle and put your hand at the tailpipe. Is it missing? You can feel even a very minor miss at the tailpipe.

 

[MCervinka]

The tach is at 800 when at idle. I will try to see if its missing at the tail pipe.

 

[rbattelle]

The tach is at 800 when at idle.

Yup, that's too high. Idle speed should be listed on the engine data plat as 750 RPM. Mine is generally 745-755. If it's holding 800 RPM at vehicle speed 0 and transmission in neutral, something may be wrong.



-Ryan

 

[DPKetchum]

750/800 the factory tach may be off a little or not that easy to read that low. I'd just see if any slight miss at tail pipe. Had a few 2 nd generation 24 valve that had VERY slight miss at tailpipe and almost impossable to feel a roughness in idle but owneres of the trucks were aware. Turned out faulty injector. Really difficult to get down to which one. If you killed a cyl. it was totaly dead. The SLIGHT miss wasn't that kind of issue.

 

[JStieger]

Let it idle and put your hand at the tailpipe. Is it missing? You can feel even a very minor miss at the tailpipe.

This is a dumb question, but how does one detect a minor miss? Is it uneven flow or a break up in exhaust flow? Different sounds?

 

[MCervinka]

Whats your view?

I think I have found a trend. There are times when the truck will be real smooth. My idea of smooth is when accelerating from idle(800) to about 2000 RPM the truck will pull without effort. You could say the way the truck should run.



Then when the truck has a ruff idle its the opposite. When accelerating from idle to 2000 rpm the truck seems to feel bogged down. The rhythm of the engine sounds different. It sounds louder and nervous. I still hear the turbo working but also here a rattle as if there isn't enough fuel - I think (the rattle will happen past 2200 rpms all the time). It feels like I have lost power. Will not pull the same. It seems to happen at the hottest part of the day so far. The engine is not running hot. The temp is right in the middle of gauge.



Now I took my truck to the dealer and ask to have a master tech do a ride along. I let him drive and the way he was revving the motor past 2600 rpms he told me that it was running fine. He told me that the motor make most of its power around 2600 rpm.



My first question would be:



Is 2600 rpm, over revving the engine being that red line is 3000 and what rpms should I shift at when shifting throw the gears. I'm shifting @ 2000 now.



My next question is with these symptoms what do you think this could be?

 

[DPKetchum]

Yes a minor or major miss is uneven air flow from tailpipe. 2600 rpm won't hurt a Cummins. It can run at or near redline with a load for HUNDEREDS of hours. Lots of folkes would do well to cover the tach up with tape and just drive. Shift it where it feels like it needs to be shifted. I rarly ever look at a tach. If it didn't have one you'd just drive and shift. Shift points vary wildy do to load,terrian etc. If it was a automatic you would not even ask that question.

 

[MCervinka]

What do you think about the other symptoms?

 

[DPKetchum]

Not sure but the quiet idle is also dependent on temp etc. First check to see if it really is a miss. No service soon light I presume? Subtle problems are really difficult. The broke/obvious are easy as a rule.

 

[MCervinka]

So This Is What The Dodge Dealer Told Me

I took my truck to the third dealer and at last they found out what the problem was. Two injectors that were not working properly. They called me and told me that the truck has consumed 25 gal of diesel at idle and thats what made these injectors stick. They also told me that because of my driving habits dodge would not replace my injectors, they will only clean them. I told them that I broke in my truck the way cummins recommends and haven't had the truck at idle for more than five minutes tops. They told me that they have to follow guide lines and if thats what the computer told them thats all they can do for me. I bought this truck with 62 miles on it and feel that this was a problem before I bought this truck and now its falling in my lap. I had this truck for close to a month now and have been trying to fix this problem for the last few weeks.



Not only do I have a injector problem I feel there is something wrong with the transmition also. It has a knocking noise and when you press in the clutch the knock will go away. The pedal feels wrong also like there might be air in the line.



Has anyone been through anything like this before?



Since the injectors were not working properly could that hurt my engine?



If they clean the injectors will they work like they should?



Any help or advice would be appreciated.

 

[DPKetchum]

My own opnion is the idle thing is B/S. Have no idea if cleaning them will fix them. If the idle deal is such a problem why is it these trucks do not come from the factory with the high idle feature TURNED on (with notations on the visor about idle time)and the other year model/six speed 3 generation trucks its not available or a update to give them a high idle feature.

 

[rbattelle]

My own opnion is the idle thing is B/S. Have no idea if cleaning them will fix them. If the idle deal is such a problem why is it these trucks do not come from the factory with the high idle feature TURNED on (with notations on the visor about idle time)and the other year model/six speed 3 generation trucks its not available or a update to give them a high idle feature.

I'll go one step further and say I think it's downright illegal to deny warranty coverage for something that is not specifically addressed in the owners manual. Where I come from, we call that "requirements creep" or "imaginary requirements". Apparently, there's some amount of idle time that is "too much" and the customer has NO WAY of knowing how much is too much.



How can anyone be responsible for failing to meet a requirement they didn't know was there?



Ask the dealer to show you the DC specification that indicates maximum idle time for the engine. If he can't, then ask him to call his boss and get him to tell you. Keep moving up the chain until you get someone to quote the maximum idle time specification for you. Then ask where that's documented in the owners manual. Ask to speak with STAR if you need to.



Oh how I wish a DRB-III wasn't $6000.



-Ryan

 

[DPKetchum]

They'll never let you speak to Star or even if you had their phone THEY would not discuss it with you. In fact Star will only speak to certain dealership employees,techs that are approved,a few service writers etc. I did know their phone number and store number were I worked. I was a approved person etc. When I left my rolodex got GONE in 60 seconds. I can't for the life of me remember their number. I could have posted it! That would have really stirred "them"up. I agree totaly with rbattelle. I think that the electronic injector technology and fuel technology is not up to snuff. Same as EARLY EFI in the mid 70s. I went through the same identical problems almost ver batum back then on gas engines. Quality of the FUEL was the biggest issue.