RV Trip Planning Discussions

Go Back   iRV2 Forums > POWER TRAIN GARAGE FORUMS > Cummins Engines
Click Here to Login

Join iRV2 Today

Mission Statement: Supporting thoughtful exchange of knowledge, values and experience among RV enthusiasts.
Reply
 
Thread Tools Search this Thread Display Modes
 
Old 03-21-2019, 09:42 AM   #1
Senior Member
 
powerboatr's Avatar
 
Damon Owners Club
Freightliner Owners Club
Join Date: Mar 2006
Location: North East Texas
Posts: 4,174
Weird ISC idle change

Yes the rig had to be sitting at home for 12 months due to health.
So this past weekend we did our first shakedown trip and cleared the cobwebs.
so as we are hooking up the towed, the rv was idling as normal to finish warming up a bit.
as i was hooking up the engine idle started climbing up, not fast,,,just a slow roll up . So i went in and checked to ensure the fast idle was not set by the cruise control.
tapped the brake pedal and the engine went back to 699 to 720 rpm. so i waited and then it started the slow roll up, first to 799 and held, then it slow rolled up to 850, fluctuating to 890. then it did it again and rolled up to 920 ish, bouncing between 920 to 940.
i tapped the brake and it it fell to idle.
this repeated three more times.
so i shut her off and waited a few.
started it back up and within a few minutes it started doing it again.
so we started the trip and drove about 20 miles to get fuel. then another 60 to the park campground.
at the park..idled as normal, no fluctuation or jumps.
so i assume a temp sensor or something was seeing an out of spec input.
i never got any check engine lights or fault codes in the light bar.
any ideas.
__________________

__________________
USN Retired, Life time member of the DAV.
Enjoying the 2008 Damon Tuscany 4056, no your eyes are fine, there are really 6 slides
2016 Expedition or 2012 Edge toads

powerboatr is offline   Reply With Quote
Join the #1 RV Forum Today - It's Totally Free!

iRV2.com RV Community - Are you about to start a new improvement on your RV or need some help with some maintenance? Do you need advice on what products to buy? Or maybe you can give others some advice? No matter where you fit in you'll find that iRV2 is a great community to join. Best of all it's totally FREE!

You are currently viewing our boards as a guest so you have limited access to our community. Please take the time to register and you will gain a lot of great new features including; the ability to participate in discussions, network with other RV owners, see fewer ads, upload photographs, create an RV blog, send private messages and so much, much more!

Old 03-21-2019, 10:23 AM   #2
Senior Member
 
FL420's Avatar
 
Join Date: Jan 2018
Posts: 985
My ISC330 has recently started doing something similar. When I start it and let it air up the coach I do it at the normal slow idle. After a few minutes the RPMs slowly but steadily increase up to the 1200 rpm fast idle just as if I had used the cruise control switches but at a slower rate. I can slow it down to the normal idle using the cruise control switches.
Unfortunately I don't remember if the CC switch was on. I think I'll go check it out after the DW wakes up. She prefers me to bring her morning coffee instead of starting the Cummins.
__________________

__________________
2005 Monaco Knight 40PLQ; Cummins 8.3L ISC330, Pacbrake, Allison 3000, Roadmaster RR8R, ScanGauge D, 2004 Kawasaki Vulcan VN750(Geezer Glide) on a Versahaul carrier pulling a 2013 Kia Soul+; 2.0L, 6 speed Sport shifter(great car) on an American Car Dolly(great dolly.)
FL420 is online now   Reply With Quote
Old 03-21-2019, 12:04 PM   #3
Senior Member
 
powerboatr's Avatar
 
Damon Owners Club
Freightliner Owners Club
Join Date: Mar 2006
Location: North East Texas
Posts: 4,174
it has only done this once since 2009


first time it was cold wet and nasty out and i chocked it up as it was trying to warm up fast.


i figured it was a ghost from sitting so long
__________________
USN Retired, Life time member of the DAV.
Enjoying the 2008 Damon Tuscany 4056, no your eyes are fine, there are really 6 slides
2016 Expedition or 2012 Edge toads

powerboatr is offline   Reply With Quote
Old 03-21-2019, 02:21 PM   #4
Senior Member
 
onechaddude's Avatar
 
Join Date: Jul 2011
Posts: 1,746
Mine isn't an ISC but rather and ISB 5.9 of 2007 vintage in my motorhome. It does this as well and is considered normal. Many of the ISB engines in my Ram trucks over the years did the same.

I think what you're experiencing is normal, especially if its cool to cold outside.

Chad
onechaddude is offline   Reply With Quote
Old 03-21-2019, 02:36 PM   #5
Senior Member
 
Join Date: May 2017
Posts: 1,163
It is normal and does that if the battery charge is low.
__________________
J.H.
2013 & 2014 DLQ Anthem 2016A & 2017W Cornerstone
2019 Ram Laramie Longhorn
Rollin101 is offline   Reply With Quote
Old 03-21-2019, 02:44 PM   #6
Senior Member
 
powerboatr's Avatar
 
Damon Owners Club
Freightliner Owners Club
Join Date: Mar 2006
Location: North East Texas
Posts: 4,174
Quote:
Originally Posted by Rollin101 View Post
It is normal and does that if the battery charge is low.
my batteries were fully charged,

one of the things i looked at was voltage and it was rock steady at 13.8 ..indicating the intake grid heater was off and not cycling.
by the time i got ol girl out of the port garage she was warm.
it was just one of them things that makes you go look and see
i think


other than a auto leveller freaking out at the cg..it was a nothing got broken trip nothing like watching all the wheels come off the ground
__________________
USN Retired, Life time member of the DAV.
Enjoying the 2008 Damon Tuscany 4056, no your eyes are fine, there are really 6 slides
2016 Expedition or 2012 Edge toads

powerboatr is offline   Reply With Quote
Old 03-21-2019, 02:53 PM   #7
Senior Member
 
Join Date: May 2017
Posts: 1,163
Quote:
Originally Posted by powerboatr View Post
my batteries were fully charged,

one of the things i looked at was voltage and it was rock steady at 13.8 ..indicating the intake grid heater was off and not cycling.
by the time i got ol girl out of the port garage she was warm.
it was just one of them things that makes you go look and see
i think


other than a auto leveller freaking out at the cg..it was a nothing got broken trip nothing like watching all the wheels come off the ground
The 13.8 was probably your alternator output not actual battery voltage.
__________________
J.H.
2013 & 2014 DLQ Anthem 2016A & 2017W Cornerstone
2019 Ram Laramie Longhorn
Rollin101 is offline   Reply With Quote
Old 03-21-2019, 03:23 PM   #8
Senior Member
 
powerboatr's Avatar
 
Damon Owners Club
Freightliner Owners Club
Join Date: Mar 2006
Location: North East Texas
Posts: 4,174
Quote:
Originally Posted by Rollin101 View Post
The 13.8 was probably your alternator output not actual battery voltage.
yes, it mentioned it as it gave me indication the grid heater was not cycling, and that meant the engine was warm enough to not run up the idle to warm up.
just one of them things, that bugged me.
__________________
USN Retired, Life time member of the DAV.
Enjoying the 2008 Damon Tuscany 4056, no your eyes are fine, there are really 6 slides
2016 Expedition or 2012 Edge toads

powerboatr is offline   Reply With Quote
Old 03-21-2019, 03:26 PM   #9
Member
 
Join Date: Jun 2014
Location: Allentown, Pa
Posts: 41
2008 8.3 ISC. Mine does the same thing, will idle up to 1500 rpms, if I tap the throttle comes right back down. Probably some engine temp strategy.
thomasd923 is offline   Reply With Quote
Old 03-21-2019, 07:05 PM   #10
Senior Member
 
oscarvan's Avatar
 
Join Date: Feb 2017
Posts: 533
Quote:
Originally Posted by Rollin101 View Post
The 13.8 was probably your alternator output not actual battery voltage.
By definition.....
__________________
2017 Berkshire 38A
https://dragonship.blog/
oscarvan is offline   Reply With Quote
Old 03-21-2019, 08:27 PM   #11
Junior Member
 
Join Date: Nov 2017
Posts: 28
You guys didn't all indicate what model year, and thereby your SCR configuration, so this information may not apply. But on a 2018 ISL this "idle up" behavior to 1000 -1200 RPM is normal and directly related to the pollution/particulate control system. I cannot repeat accurately the details as explained to me by a Cummins mechanic, but basically the SCR system depending on several factors and sensor readings will call (via the ECM) for engine "idle up" to generate heat needed by the SCR system to either allow it to operate properly and/or prevent the system from being damaged or clogged.

This "idle up" generally happens on colder days after engine start up when SCR is otherwise not warm enough to operate as designed. On hot days or at highway speeds or when engine and SCR system is warm at idle after highway driving, the SCR system has all the heat it needs.

Understand that I have just told you more than I actually know.

Hope this helps,

DeetsMaggie
DeetsMaggie is offline   Reply With Quote
Old 03-22-2019, 06:54 AM   #12
Senior Member
 
spdracr39's Avatar


 
Monaco Owners Club
Join Date: Jul 2016
Location: Cabot, Arkansas
Posts: 1,413
Quote:
Originally Posted by DeetsMaggie View Post
You guys didn't all indicate what model year, and thereby your SCR configuration, so this information may not apply. But on a 2018 ISL this "idle up" behavior to 1000 -1200 RPM is normal and directly related to the pollution/particulate control system. I cannot repeat accurately the details as explained to me by a Cummins mechanic, but basically the SCR system depending on several factors and sensor readings will call (via the ECM) for engine "idle up" to generate heat needed by the SCR system to either allow it to operate properly and/or prevent the system from being damaged or clogged.

This "idle up" generally happens on colder days after engine start up when SCR is otherwise not warm enough to operate as designed. On hot days or at highway speeds or when engine and SCR system is warm at idle after highway driving, the SCR system has all the heat it needs.

Understand that I have just told you more than I actually know.

Hope this helps,

DeetsMaggie
I think you probably nailed it.
__________________
2004 Beaver Monterey Laguna/2015 Chevy Equinox
2014 Chaparral 327RLKS 5'er (FOR SALE)
2017 GMC 2500HD SLE 6.0L Z71 4x4 Standard Bed
https://wordpress.com/posts/enjoying-life.net
spdracr39 is online now   Reply With Quote
Old 03-22-2019, 08:59 AM   #13
Senior Member
 
FL420's Avatar
 
Join Date: Jan 2018
Posts: 985
Quote:
Originally Posted by spdracr39 View Post
I think you probably nailed it.
Maybe if the coach has SCR, DEF and DPF. The OP's coach, and my coach, have none of that. In my case that was a major purchasing decision.
__________________
2005 Monaco Knight 40PLQ; Cummins 8.3L ISC330, Pacbrake, Allison 3000, Roadmaster RR8R, ScanGauge D, 2004 Kawasaki Vulcan VN750(Geezer Glide) on a Versahaul carrier pulling a 2013 Kia Soul+; 2.0L, 6 speed Sport shifter(great car) on an American Car Dolly(great dolly.)
FL420 is online now   Reply With Quote
Old 03-22-2019, 03:33 PM   #14
Senior Member
 
powerboatr's Avatar
 
Damon Owners Club
Freightliner Owners Club
Join Date: Mar 2006
Location: North East Texas
Posts: 4,174
well thats easy, bus in in my signature but,

its a 2008 ISC, with only the DPF after treatment.


a note that on weds morning getting ready to leave cg, it was 45F and starting to warm up, with low humidity.
engine started normally and idled for at least 10 minutes while jacks were brought up and we hooked up the edge.
engine idled 100% normal. no idle up or mis steps, just steady idle.
on the day we left home and this even happened it was about 50F and with low humidity.


so if ecm was looking to warm up the DPF , i would think it would do it on both start ups.

i only brought it up as it was OUT of normal operation for my ISC over the last ten years. never thought it would become a russia incident.


and i am 100% sure the engine batteries were at least 95% charge state as the rv is 100% hooked up to power and the bird works perfectly, and the intial startup after sitting since sept, when it ran at high idle for an extended period during the a/c recharge. it fired up almost as soon as it spun over.
__________________

__________________
USN Retired, Life time member of the DAV.
Enjoying the 2008 Damon Tuscany 4056, no your eyes are fine, there are really 6 slides
2016 Expedition or 2012 Edge toads

powerboatr is offline   Reply With Quote
Reply



Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
To idle or not to idle jmoffat Caterpillar Engine Forum 36 05-11-2014 10:54 PM
No oil pressure at idle 350 ISC Jeff753 Cummins Engines 27 09-05-2013 03:18 PM
What is max turbo boost supposed to be..& min. oil pressure at idle, ISC 350 Cummins StansCustoms Alpine Coach Owner's Forum 10 12-02-2011 01:06 PM
94-Cummins 8.3 ISC Idle Adjustment 94-Newmar Cummins Engines 7 02-01-2010 08:17 PM
ISC idle speed ecp3031 Cummins Engines 10 03-04-2008 03:10 PM

» Featured Campgrounds

Reviews provided by


Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -6. The time now is 08:06 PM.


Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2019, vBulletin Solutions, Inc.