Excessive Idle Time can Cause Poor Engine Performance

I-RV · 04-29-2015, 02:05 PM

"Excessive idle time can cause poor engine performance". This statement is out of the Cummins manual. See the attachment. When running my engine periodically when being stored, I knew to keep the rpm's over 1000; but this is tiresome to the foot.

There is a built-in feature for setting faster idle speeds; probably half of you know and the other like me awhile ago, didn't.

With engine running, in neutral, parking brake set; put the cruise control to ON. Tap the cruise engage button once and the idle goes up to around 1,100 and stays there. Tap it again, and it goes higher. Tap the Resume button and it goes down,

This is a great most over-looked feature. In cold weather, it can be used to warm the engine up a lot quicker. I always start at normal idle first for a few minutes, to get everything oiled-up.

Campin Cajun · 04-29-2015, 05:28 PM

I use this feature a lot. When warming the coach and also if I sit a redlight for a long time or if I am stuck in traffic.

JTN8 · 04-29-2015, 05:44 PM

Quote:

Originally Posted by Campin Cajun

I use this feature a lot. When warming the coach and also if I sit a redlight for a long time or if I am stuck in traffic.

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Phil57 · 04-29-2015, 05:53 PM

I also use it if stuck in traffic. I also had to use it because of terrible planning on our part. That is the only reason I can explain being in below freezing temperatures when your house has wheels. I miss my nice warm Florida weather.

Hallen01 · 05-07-2015, 04:12 PM

Quote:

Originally Posted by I-RV

...There is a built-in feature for setting faster idle speeds; probably half of you know and the other like me awhile ago, didn't.

Hank - I tried it and it worked as advertised. I don't think this was covered during the Camp Freightliner I attended - thanks!

nastygts · 05-09-2015, 07:40 PM

Ive learned over the years that the 6.7 in the Ram trucks do auto idle up when idling for extended period to kick off the "regen" process.

I noticed today that my MH went into high idle about 5 minutes after starting it. ( checking everything over for first trip of the year next week) Sure enough one of the DEF fluid lights turned off and shortly after the engine idled back down.

May or may not be a good thing for you guys that are stationary for extended periods. Not everyone has the access to a long stretch of road to get the regen started and completed.

dan-nickie · 05-09-2015, 08:43 PM

BUT, I have never been able to find a Cummins document that states exactly what 'excessive idle' means.

Is it 10 minutes, and hour, 5 hours, 12 hours?

Phil57 · 05-09-2015, 09:39 PM

Me nether Dan. I just run mine long enough to get the air up do a last minute walk around and take it slow before I get to highway speeds. As far as I know my engine has never gone into regen.

I-RV · 05-10-2015, 07:49 AM

Yes, the term Excessive is nebulous. However, the technique of how to increase idle rpm with the cruise control might be valuable for those that did not know about it. The increased idle may be invaluable for warming the engine in brutal cold weather and when doing the periodic engine runs when in storage or setting for some time.

dan-nickie · 05-10-2015, 08:40 AM

Hank, I was just responding to the thread title about 'excessive idle'.
I still wish I knew what cummins considers 'excessive' since it is mentioned so often.

I use the idle up most of the time soon after starting a cold engine also if for no other reason than to maybe get the air bags up quicker.

Since I read about it on here before I bought my MH I assumed most people knew about it.
You are probably right that many do now know,

Campin Cajun · 05-10-2015, 08:22 PM

It was soooo easy before DEF and all the new regs put on diesel engine manufacturers. Crank her up and let it idle for days.

I've heard and read 5 minutes is long for idle time. This is not written in stone tho.

scootingranny · 05-10-2015, 08:36 PM

Does this apply to the Cummins diesel in a pick up too? Just got our truck Saturday so we didn't know this.

Campin Cajun · 05-11-2015, 09:09 AM

scoot, I would think it applies to all diesel engines having to run DEF.

dan-nickie · 05-11-2015, 01:57 PM

Quote:

Originally Posted by Campin Cajun

It was soooo easy before DEF and all the new regs put on diesel engine manufacturers. Crank her up and let it idle for days.

I've heard and read 5 minutes is long for idle time. This is not written in stone tho.

5 Minutes sure does seem short after watching big trucks idle all night long.
I had read a couple of opinions, but nothing from Cummins that I can take to the bank.

TGR · 05-11-2015, 02:36 PM

Wet stacking is a problem with diesel engines and isn't limited to the Cummins engine or just because of DEF requirements. "Wet stacking" happens when a diesel engine is run too long with no load and operates below its optimum temperature. Unburned fuel can foul the fuel injectors, valves, turbochargers and more.

To overcome this problem during long idle periods, the engine must run at a fast idle, especially in cold weather, to keep the engine temperature up.

Campin Cajun · 05-11-2015, 02:37 PM

I agree Dan, but it is almost impossible to find something stating how long slow idle time is. It's frustrating.

I go with the 5 minute rule on my coach. I'm probably way early on it but I rather be safe than sorry.

dan-nickie · 05-11-2015, 03:42 PM

Quote:

Originally Posted by Campin Cajun

I agree Dan, but it is almost impossible to find something stating how long slow idle time is. It's frustrating.

I go with the 5 minute rule on my coach. I'm probably way early on it but I rather be safe than sorry.

I know waht you mean. I probably way overcompensate and try to ilde as little as possible. I know someday I'm going to fee like a fool when Cummins comes out some day and says 'excessive idle' is over 2 hours.

Witch Doctor · 05-11-2015, 04:07 PM

I hope you guy's don't do that at a CG. My truck doesn't use DEF, My manual says no warm up period is necessary. I can understand warming up your coaches til air tanks are full. Then just pull out and go slow. I have seen people at 6:00 AM start there MH and let them run for 1/2 hour before they pull out. I'm sure they do not mean that. I know all FR members are considerate to there neighbors, but also I understand that they have to start to pump that DEF. But not a half hour as I have had done to us more then once. Maybe someone should find out what they recommend being nobody on this thread seems to know. As much money you guy's paid for them beautiful units, I would be making a call. Just a suggestion. And I know this is a MH thread, but I'm the one who has to listen to it. But I still do not want you to damage your power system......And I do not mean to offend anyone.

Campin Cajun · 05-11-2015, 04:33 PM

You seem upset gljurczyk???

Witch Doctor · 05-11-2015, 05:13 PM

Quote:

Originally Posted by Campin Cajun

You seem upset gljurczyk???

I'm not upset at all just making a comment. I guess you took the statement wrong. I thought I made that clear. But I guess I didn't. Maybe you should reread the comment. But I would make sure what they mean by Idling and what is safe not to damage your engine. Sorry if you took it the wrong way.....

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