Truck Shaking/High Idle
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From: Western, Pa
Truck Shaking/High Idle
I notice/feel my truck "shaking" when the high idle kicks in or when I press the go pedal and the RPM's get up to 1k. This is when truck is in park. It has never done this before. It's doing it when cold and warmed up. It seems to be running fine, "low/normal" idle is smooth and engine is quiet. The shaking feels similar to driving it with a flat spot in the tires, but doing at idle. Any ideas?
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From: Antioch, Ca
I don't have the high-idle enabled on mine, but I do know if it's really cold outside *California standards of real cold = 20 degrees* it will kick up the idle a bit higher than the normal high idle on a semi-cold morning and runs more rough. I've heard it doesn't fuel 2 of the cylinders to act as resistance causing the engine to warm faster? Someone should be able to confirm that.
I do know it sounds like a train just pulling out of station...CHUG...CHUG...CHUG
I do know it sounds like a train just pulling out of station...CHUG...CHUG...CHUG
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From: Ila georgia
I don't think the shaking or chuging is normal.Some slight roughness in cold can occur for a few seconds on cold start but truck does not have a program to shut down any cyls on a cold start.It may make you feel better to think it does but it dosen't.
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From: Antioch, Ca
The way it works is this: If coolant is below 140, and air intake is below 40 degrees F, then the idle speed ramps up to 1200. after the ramp, if the air intake is 32 degrees or below, and the coolant temp is still below 140 then three cylinders shut down. there are more details listed in a TSB. Don't quote me on the absolute numbers; I'm going from memory here.
I had this done when I first got my truck, so it was free. When it goes to 3-cylinder, it is something else!
I have wondered about moving that sensor from under the battery to someplace else to avoid the sun heating the fender and then the sensor. cause alot of the time it can be 5 or 6 degrees but really sunny here and it wont high idle. yeah my neighbors hate the 3 cyl thing
except one guy across the street who loves it came over one morning at 6:00 when I started it said he had heard it 3 days ago and had to come see what it was I apologized for the noise but he said no worries, he is an implement parts dealer and used to build and tune pulling tractor engines so he is pretty cool but everyone else really hates it.
except one guy across the street who loves it came over one morning at 6:00 when I started it said he had heard it 3 days ago and had to come see what it was I apologized for the noise but he said no worries, he is an implement parts dealer and used to build and tune pulling tractor engines so he is pretty cool but everyone else really hates it.
The 3 cylinder feature is a sub-feature of the high idle routine. You do not have to enable the 3 cylinder feature when you activate the high idle feature. Actually, my local Cummins dealer recommended getting the high idle feature enabled to ward off SVS, but recommended against enabling the 3 cylinder feature when I talked to them about it. He told me that is a Dodge thing and not a Cummins feature.
Symptom/Condition:
Extended idle operation, especially in cold weather, can lead to stuck valves and bent push-tubes due to insufficient cylinder heat. This allows varnishes/oils to condense on the exhaust valve stems, leading to stuck valves, and damaged valve train components. A new software feature, enabled or disabled through the DRB III (See instructions under Repair Procedure), reduces the chance of valve sticking and improves cab heat warm-up time.
Once enabled, idle speed will slowly ramp up from 800 rpm to 1200 rpm when all of the following conditions are met:
1. Intake Manifold Temperature less than 0°C (32°F) and,
2. Coolant Temp is less than 60°C (140°F) and,
3. The Transmission is in Neutral or Park and,
4. The Service Brake pedal is not depressed and,
5. Throttle = 0% and,
6. Vehicle Speed = 0 mph
Additionally, if Intake Manifold Temperature (IMT) is less than -9°C (15°F), and all of the parameters above are met, three of the cylinders will be shut off upon reaching 1200 rpm, creating a slight change in engine sound which is normal. This allows the engine to create increased heat in the cooling system, allowing more rapid engine warm up and cab heating.
Both features will automatically disable when one of the following occurs:
1. The Automatic Transmission is placed in gear (forward or reverse) or,
2. The Service Brake pedal is depressed or,
3. Throttle position is greater than 0% or,
4. Vehicle Speed is greater than 0 mph or,
5. Coolant Temperature is greater than 79°C (175°F).
Extended idle operation, especially in cold weather, can lead to stuck valves and bent push-tubes due to insufficient cylinder heat. This allows varnishes/oils to condense on the exhaust valve stems, leading to stuck valves, and damaged valve train components. A new software feature, enabled or disabled through the DRB III (See instructions under Repair Procedure), reduces the chance of valve sticking and improves cab heat warm-up time.
Once enabled, idle speed will slowly ramp up from 800 rpm to 1200 rpm when all of the following conditions are met:
1. Intake Manifold Temperature less than 0°C (32°F) and,
2. Coolant Temp is less than 60°C (140°F) and,
3. The Transmission is in Neutral or Park and,
4. The Service Brake pedal is not depressed and,
5. Throttle = 0% and,
6. Vehicle Speed = 0 mph
Additionally, if Intake Manifold Temperature (IMT) is less than -9°C (15°F), and all of the parameters above are met, three of the cylinders will be shut off upon reaching 1200 rpm, creating a slight change in engine sound which is normal. This allows the engine to create increased heat in the cooling system, allowing more rapid engine warm up and cab heating.
Both features will automatically disable when one of the following occurs:
1. The Automatic Transmission is placed in gear (forward or reverse) or,
2. The Service Brake pedal is depressed or,
3. Throttle position is greater than 0% or,
4. Vehicle Speed is greater than 0 mph or,
5. Coolant Temperature is greater than 79°C (175°F).
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From: Ila georgia
What year model is this refering to? The automatic high idle on 3rd generations is not but 1000 rpm.Not 1200. I have read that the 3 cyl warmup is a 2nd generation thing but not a 3rd generation(03 up) Ok I just did a quick search on 3cyl.1200 rpm high idle. It was a 2nd generation 24 valve thing.It was NOT used or carried over to the 3 rd gen.trucks.My quick search was on TDR and I found almost the very same wording as posted above but ONLY for 98.5 to 2002 24valve trucks with a notation that was not used on 3rd generation trucks. I assume that it must be LOUD when it does a 1200 rpm 3 cyl.deal as one poster comments about how it scared his neighbor whom came over concerned at all the noise that early in the morning etc.
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From: Ila georgia
This has been brought up a few times in the past.It was only 2nd gens.I guess lots of 3rds run kinda rough cold but by no means like three cylinders are dead.Mine was a little rough on cold start until the crank sensor mod and its smooth at any temp on cold start.
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From: Western, Pa
I don't know, maybe it's normal, but I don't remember feeling this shaking. It doesn't feel or sound like any of the cylinders shut down. It's almost as if a crank balancer or something is off causing the engine to shake. Thanks for the replies guys, maybe I'll run it up to the dealer and let them have a look
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From: Ila georgia
Its not normal if it last more then 10/15 seconds.Mine did it some when new.The Rokktech crank sensor(advances timing about 2 degrees) is the only change I made that ought to affect this made a differance.Mine is smooth running on cold start other then the 1000 rpm idle fluxuating with the grid heaters cycling.
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Mine scared the heck out of me!!!!
I added a Smarty programmer to mine this past spring and evidentally that thing enables the high idle and the 3 cylinder idle. I was up deer hunting last week and I went out and started the truck and went back in the cabin to let the truck warm up. In a few minutes I realized that the trucks idle had raised a bit, then I remembered that there was some idle reprogramming associated with the smarty.
Well tonight, I backed it out of the shed to get the tractor out that was in front of it and let it run. It was a bit colder tonight and obviously the 3 cylinder idle conditions were met because it went clatter a heck of a lot louder than usual. My first reaction was to run over in a panic to shut it off because my first reaction was that it had lost oil pressure or something. But, I remembered the 3 cyl idle mentioned on this site and decided to let it play out. I let it warm up and it went back to normal on its one once warmed up. My 3 year old son (future motor head) looked up at me and said "daddy, I think something is wrong with your cummins "turtle" dieso". Funny kid...
Well tonight, I backed it out of the shed to get the tractor out that was in front of it and let it run. It was a bit colder tonight and obviously the 3 cylinder idle conditions were met because it went clatter a heck of a lot louder than usual. My first reaction was to run over in a panic to shut it off because my first reaction was that it had lost oil pressure or something. But, I remembered the 3 cyl idle mentioned on this site and decided to let it play out. I let it warm up and it went back to normal on its one once warmed up. My 3 year old son (future motor head) looked up at me and said "daddy, I think something is wrong with your cummins "turtle" dieso". Funny kid...
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My 3 year old son (future motor head) looked up at me and said "daddy, I think something is wrong with your cummins "turtle" dieso". Funny kid...
The odd time mine will chug slightly for a few seconds on a real cold start ... like -30. Anymore than that I'd say is not normal nope.
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From: Atlanta, IL
I have noticed a slightly rough idle when in high idle mode. Comes and goes. Had it yesterday sitting at the bank. Engine temp was at about 180 though and I had been driving for the past hour.
Other than that truck runs like a raped ape. So I'm not sure what to think of the rough idle.
Other than that truck runs like a raped ape. So I'm not sure what to think of the rough idle.
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