Engine lope on fast idle

[retirednak]

I just changed fuel filter and the old filter looked great for being a year old... . and only 3K miles,no water in the housing or visable goodies. Took the truck to Anchorage 55 mile trip,with no troubles and everything seemed normal. Got to town early and sat to read the newspaper,after a few minutes the truck kicked up on high idle. Nothing unusual,the truck did this bout 3 times cycling back and forth and then on high idle I thought the truck started to lope a little bit. First reaction was to touch the brake and bring the engine back down. I turned it off and looked for a fuel leak around the housing and didn't see or smell a leak. Started back up,after a few minutes, back up on fast idle and it started the slight lope again. Its a very slight lope and I've never experienced this before. When I got back to my area,I left the truck running while I went inside for business and listened to my truck cycle back and forth and never heard the lope again. I did drive the truck hard and at high rate of speed to get the RPM's up on the way back, thinking I'll either break it or break loose the crud causing the problem. The only thing I've done different lately is added Wally world 2 stroke oil along with my usual dose of Power service. to this tank of fuel. Engine seems a tad smoother and quieter. Starts normal,no unusual smoke. WTF? 99600 miles on the clock and nothing has been touched except for whats in my sig.



Sorry bout being so long winded.

Thanks in advance-Casey

 

[mwilson]

Had mine out last Saturday, it was 10-12 degrees with the wind blowing hard. Everytime time that the truck kicked itself up to 1000 rpm it would lope the same way as yours. It will get quite bad at times. I then remembered that it did the same thing last winter on cold days. I have put it to nature of the beast and kick it up to 1100 with the cruise if I happen to be in the truck. At 1100 it is as smooth as silk. Putting my new engine brake next month and should keep it warm at idle on a cold day.

 

[retirednak]

I've never run into this issue,even at -40 degrees or colder up North. I always use my MOPAR winter front and let the truck warm up if needed.



I don't think I can increase my idle speed using my cruz,believe my trucks a tad too old for that.

 

[mwilson]

Good Morning,

I was half asleep when I posted last night and will give you a little more detail regarding my loping Cummins***

It did not do it until I added the Edge w/Attitude the second year I had it. I don't know if that is related to the symptom or not. It will only do it if you have driven the truck enough for it to reach operating temperature, then stop and let it idle. Then it takes about 15 minutes on high idle until it begins to lope. The first time it did it I checked frigin' everything, full panic!!

Can't find anything wrong and now am used to it. It has to happen to me once a winter so as to remind me to set it to 1100 before I go off and leave it running.

I don't let it idle like that as a rule, usualy start it, let it warm up a bit and drive it 65 miles but had to take the dog with me Saturday and didn't want to freeze my little friend out in a parking lot. :{

I see that you show an Edge product in your signature, maybe unhooking it for a day would prove if it is involved or not. I suspect it might be the reason. I would unhook mine as a test for you but I hate to unplug plastic connectors in these temps and would have to garage it for a day. Maybe your truck has a warm place to sleep so that you could easily unhook it temporarily??

 

[retirednak]

You know,that does make since. I was running my Mileage Max trying for better mileage. It gives a much better off the line throttle response and does boost performance... ..... some. I might get 1/2 mpg difference. But it also makes my turbo,chatter if your in traffic with lots of on & off throttle action. It also screws my cruise control up because of the overly sensitive throttle. So I just swapped back to my EZ Edge and I'm on the highest setting. I'm able to use CC and I can really tell the difference on the low end.

I'm still unhappy with my very poor fuel mileage since day one.

After talking with regcabguy,he suggested a Smarty. I may go ahead and upgrade and see if I can enjoy the added increase and not cause any weird things to crop up.

 

[cerberusiam]

The lope on the auto high idle seems to be a normal thing on a lot of trucks, not all but more than a few.



From what I have seem of scope graphs it has something to do with the ECU splitting the main even to aid warmup. Several have reported when they loaded Smarty it quit and never did it again.



Mine has never done it at all Smarty\no Smarty so it evidently takes a certain se tof circumstances to hear it.

 

[retirednak]

Thank you for the info

 

[Svend]

Mine has done it since day one. With or without the xzt. Seems to be a 325/600 anomaly.

 

[mini14]

the other day its 15 degrees out start truck instant high idle no lope, drive to sev elev, leave it runnen, come out to high idle with heavy lopeing, truck moving from side to side... . most other times it lopes from the first cold start. other then that it runs perfect. It does have a constant haze out the exhaust at night in headlights. during the day i dont c a thing.

 

[hearingyourlies]

mini14 you described my truck to a T. And i've never had any kind of power adder since day 1. Currently 89k miles.

 

[Wingate]

If I manually put mine at 1100 rpm, it doesn't do it. If its extremely cold outside and ramps itself up to about 1000 RPM, it will surge also. While i'm not completely certain, I believe it to be a selective cylinder cutout thats causing a slight hunt in the sound of the engine.

By selectively killing cylinders, you are INCREASING the load on the other cylinders, thereby causing them to generate more heat.

Maybe one of the Cummins/Dodge techs can chime in and correct/clarify this???. .

 

[steved]

My lope was caused by failing injectors...



I also had a sensitive cruise, also caused by failing injectors...



Good luck.

 

[LCartier]

mine went away with new injectors. never loped from day one in high idle, it just started one day and got progressivley worse. so bad was the lope it was like a gasser racing cam, truck was shaking. new injectors, lope is gone even at high idle!

 

[Wingate]

the surge that I hear on my truck isn't even enough for it to register on the tach... but you can hear it. I watched the tach for a minute the other day and it doesn't move.

It better not be injectors... truck only has 30k on it... hahaha. .

 

[JamesStevens]

Mine lopes pretty bad when it goes to 1000rpm on its own. If I kick it up to 1100rpm or higher it is smooth as silk. The 2nd gen guys will say its just there VP-44 motors that cut out 3 cylinders, but I was sure I read somewhere ours will to. U would think it would be even easier to implement with our electronic motors.

 

[JBlakeman]

I'm still on original injectors with close to 134,000 and it has loped, surged, etc. when high idling. The colder the air temperature and if the engine is cold, the more noticeable and pronounced it get's (enough to clearly move the tach between 950 - 1100 RPM). I've had every TSB, flash done to the truck and all components checked. Smarty or not it has never really made a difference.

 

[MChrist]

Wingate, I believe the 3 cylinder cold idle setting is only on the Second Gen motors, not the HPCR motors we have. For the record, mine doesn't lope at high idle or anywhere else but only has 51,000 miles

 

[RaymondSmith]

Mine has the "lope" too if it idles up by itself. Set the high idle with the cruise button and perfectly smooth. Weird but I'm not going to worry too much about it based on others having the same situation.



Ray

 

[Wingate]

Wingate, I believe the 3 cylinder cold idle setting is only on the Second Gen motors, not the HPCR motors we have. For the record, mine doesn't lope at high idle or anywhere else but only has 51,000 miles

hhmm... mine will do it if its cold enough for it to initiate the auto throttle up, but like I stated before, if I put it on 1100 (PTO mode) it doesn't do it. My truck only has 30,000 on it. Maybe the software for the cold-mode throttle up makes timing and/or pressure adjustments to help build heat??

The Cat engines have both, a cold cylinder cutout, and a cold fuel timing and pressure adjustment. I would think the Cummins would have something similar.

 

[AWise]

At auto high idle (1000) or manual at 1100 mine does the same thing. If I bump it up to 1200 or higher it goes away. Still runs great!