ChargerLighting

I have an '05 Ram 3500 w/the 5.9, auto. It just started getting cold around here & my truck is doing the same high choppy idle it did last winter.
I let the heaters cycle (didn't have it plugged in) & it does it even if its' plugged in or not.

It has just under 130,000 miles on it, only under hood mod is a CAI. Exhaust is straight 5". Fuel filter is new (might have 250 miles on it).

Other than this, it runs & drives fine...no check engine lights. It did the same thing all last winter just after I bought it. & once I touch the gas pedal, it goes back to a normal idle....then it'll start the choppier idle againa few minutes later. Video is below.
I just don't know why its' doing it?? Its' kind of annoying. If its' doing it while I'm in the truck, it shakes it so much I can watch my antenna swing back & forth...

https://www.youtube.com/watch?v=zTYU...ature=youtu.be

steelblitzkrieg

Sounds like 3 cylinder warm up.

My 2006 does when it's cold enough.

Every body I've asked at Dodge has stated they did away with 3-cylinder warm up when they either introduced high-idle or the 3rd gen.

I don't believe them...

Chug-Chug-Chug

BarryG

Agree with Steel. While I don't have a 3rd gen and have no idea if/when they did away with it it sure sounds like the 3cyl idle. Must be chilly up there as it is was here this morning -5deg. Seems to me on my 2nd gen it doesn't kick in unless it is 0deg but maybe it is higher than that. I know first time mine kicked in I thought what the heck is this going to blow. On my 2nd gen it starts with regular idle, then if cold enough after 30 seconds it ramps up to the high idle then if still cold enough it switches over to the 3 cyl high idle.

ChargerLighting

I checked my overhead & my thermometer was reading 32 degrees just before I took the video. I can drive it for over an hour & park it for a few minutes, & it'll still start doing this when its' cold out.

Just before this vid, I had parked it & it was idling normally, then idled a bit higher, then it sounded like it went to 3 cyl like you described.

StealthDiesel

The choppy idle in your video is harsh.

32F/0C is not cold, so that's not the issue. I've never had my truck do that in much colder weather.
I'm quite sure the 3rd Gen CR engines do not have the 3 cylinder cold idle feature, only the VP44 engines.

Do you have a programmer installed on your truck or some type of interceptor aftermarket module?

Is the CEL on when the truck gets the choppy idle?

I'm tending to think you have injector issue but not sure. I would keep a close eye on the engine oil level to make sure it's not going up.

BarryG

Well that certainly doesn't sound right. Assuming it is the 3cyl idle I think it is the IAT (intake air temp) sensor that the ecm gets its temp from for that operation, perhaps it could be bad. You might be able to do a search on here and see if someone has posted some ohm/temp values for it then you could test it and see if it is the sensor.

47Dodge

YUP! My 2005 does the lumpy idle or a nice smooth idle if I use the cruise idle up feature. Lots will tell you they don't do it but they do!




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ChargerLighting

It has the same choppy idle in 32 degrees as it did when the air temp was about -15 last year. No programmer on the truck; never have had one on it. Check Engine light has never come on. Just had the oil change done when the fuel filter got changed.
I had it at the dealer I usually go to last year while it was doing the choppy idle, & they scanned it then & said nothing was wrong.

steelblitzkrieg

Don't trust the O/H on temp readings, it may be correct many times, but I've had mine read 73 degrees all day when it was 95+, I've also experienced the opposite, reading well warmer than it was.

I'm sticking with being normal as I posted earlier.

Maybe it's a feature that gets enabled when you have the dealer activate High-Idle, don't know...but if you search around for 3-cylinder idle videos you'll find they all sound similar to your video.

steelblitzkrieg

Well, now I've been looking around the last hour or so and every where I see, 3-cylinder warm-up is not on the CR's.

But I did read some interesting things that would create a lopey high idle.

ECM changes timing, ECM changes injection event duration.

Both make sense and both would still make it normal, now maybe some ECM's got the file and others didn't, but there is enough inquiries out there involving new trucks that it leads me to continue believing that it is an intended event.

marder

Mine does it. 3 cyl high idle. Better then no high idle. I enjoy not sticking something on the pedal like I have to do with my 12 valve. What is this cruise control idle you speak of?

ChargerLighting

I tried the cruise / high idle just to try it; won't work....cruise comes on, but, won't set. But I have an automatic & I don't think it will set unless you're going at least a certain speed

StealthDiesel

The manual cruise control high idle is another discussion.
A search on this forum will bring up tons of information on that.
It has to be enabled with an aftermarket programmer or by the Chrysler dealer. A manual trans will require a ground jumper to be added to the ECM.

I still don't believe that the CR Cummins has a 3 cylinder cold high idle option and my truck has never idled that roughly even in much colder temperatures.

Like I said earlier, keep an eye on your engine oil level and start planning to pull your injectors to have them tested, especially if you don't have additional fuel filtration.

marder

If this isnt 3 cyl high idle why does it stop after achieving a target temp? Seems to me if it was some kind of failure it would do it constantly.

47Dodge

Mine will cycle . If the truck runs itself up to high idle 1000rpms it will do the lumpy idle. If I turn on the cruise and bump up the idle on my own to 1000rpms it does not do the lumpy idle. In cold weather idling it will cycle itself and bring up the rpms and lump a long for a few minutes and then idle back down to normal idle.




47