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03-09-2022, 07:56 PM
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#1
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Junior Member
Join Date: Sep 2019
Posts: 2
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Acceleration
I have a allegro bus Cummins ISL 400 slow getting off up to bought 20mph then it just takes off runs fine on out accelerates ok until it stops then on take off same thing slow getting off
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03-10-2022, 05:37 AM
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#2
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Senior Member
Winnebago Owners Club
Join Date: Apr 2014
Location: Florida Keys
Posts: 933
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We have a 360 HP cummins. It has 1075 ftlb of torque. We run run around 35000 lbs GCVW.
Technically it "accelerates" because it does go from zero to 60 MPH but it a very gentle affair.
The only real feel of acceleration is in 1st gear for about 1 second after the turbos have spun up and before it shifts to 2nd.
__________________
2013 Winnebago Journey 36M DP. Full time since 2015. 1987 FJ60 Flat Towed,  FAILING 2000W of GRAPE Solar, 800AH LifeBlue LiFePO4 batteries (excellent), SMI Toad Brakes.
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03-10-2022, 08:13 AM
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#3
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Senior Member
Join Date: Oct 2002
Location: Madison, MS
Posts: 10,527
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Quote:
Originally Posted by Roy james
I have a allegro bus Cummins ISL 400 slow getting off up to bought 20mph then it just takes off runs fine on out accelerates ok until it stops then on take off same thing slow getting off
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Can you verify IF the tranny is downshifting all the way to 1st gear when you stop? If not, that may be the cause. You probably have an Allison 3000 tranny with 6 speeds, including the 2 "overdrives".
The only other thing I can think of is that the brakes are not fully releasing quickly. I believe the coach "should" at least start moving immediately after lifting off of the brake pedal, without touching the throttle pedal.
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03-10-2022, 03:40 PM
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#4
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Senior Member
Join Date: Aug 2001
Location: North America somewhere
Posts: 30,982
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Cummins and Allison derate the engine torque from a dead start to prevent transmission damage, then release that derate when the computers are satisfied it is safe to do so. Read your owner's manuals closely.
__________________
2000 Winnebago Ultimate Freedom USQ40JD , ISC 8.3 Cummins 350, Spartan MM Chassis. USA IN 1SG 11B5MX,Infantry retired;Good Sam Life member,FMCA. " My fellow Americans, ask not what your country can do for you, ask what you can do for your country. John F. Kennedy
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03-10-2022, 04:23 PM
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#5
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Senior Member
Join Date: Jul 2014
Posts: 35,446
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They also debate to prevent smoke at take off. Remember the black smoke all diesels used to belch.
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03-11-2022, 04:46 PM
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#6
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"Formerly Diplomat Don"
Newmar Owners Club
Join Date: Apr 2005
Location: Moorpark, Ca.
Posts: 24,125
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Just remember.....diesel motorhomes don't accelerate, they gain momentum! You're also running a turbo which takes time to build power.
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Don & Mary
2019 Newmar Dutch Star 4018 (Freightliner)
2019 Ford Raptor
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03-11-2022, 05:09 PM
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#7
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Community Moderator
Monaco Owners Club
Join Date: Jul 2016
Location: Central, Arkansas
Posts: 11,294
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Sounds pretty normal to me also.
__________________
2004 Beaver Monterey Laguna IV
Cummins ISC 350HP Allison 3000 6 speed
2020 Chevy Equinox Premier 2.0t 9 speed AWD
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03-11-2022, 07:20 PM
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#8
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Senior Member
Gulf Streamers Club Ford Super Duty Owner
Join Date: Aug 2015
Location: Memphis, TN
Posts: 4,347
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MY first thought is that it is NOT going into first gear, starting off in 2nd or higher?
__________________
(TerryH.) 2000-GS Conquest Limited 6266 Class-C 99-E450SD V10 
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03-12-2022, 07:44 AM
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#9
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Senior Member
Join Date: Feb 2015
Location: Huntingtown, MD
Posts: 834
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Are you throwing any codes? Turbo pressure OK? I had a similar problem, throwing codes, low turbo pressure resulting in very slow starts. I knew I had a problem because I have owned the RV for many years. I replaced the EGR valve and problem solved.
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Earl & Sharon, 2008 Fleetwood Expedition, ISB 6.7
1995 Jeep YJ/2013 Chevy Sonic
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03-12-2022, 07:48 AM
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#10
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Senior Member
Join Date: Oct 2014
Posts: 7,882
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Quote:
Originally Posted by THenne1713
MY first thought is that it is NOT going into first gear, starting off in 2nd or higher?
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Really easy to verify.
Put transmission in D, then down arrow to 1st gear. Does it accelerate the same as in D???
__________________
Brett Wolfe
Ex: 2003 Alpine 38FDDS. Ex: 1997 Safari Sahara. Ex: 1993 Foretravel U240
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03-12-2022, 07:58 AM
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#11
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Senior Member
Winnebago Owners Club Workhorse Chassis Owner
Join Date: May 2016
Location: Kamloops, BC, 60 miles from the Center of the Universe according to the Rinpoche, of the SF monks.
Posts: 7,397
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Quote:
Originally Posted by Ray,IN
Cummins and Allison derate the engine torque from a dead start to prevent transmission damage, then release that derate when the computers are satisfied it is safe to do so. Read your owner's manuals closely.
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0 
__________________
Happy Glamping, Norman & Elna. 2008 Winnebago Adventurer 38J, W24, dozens of small thirsty ponies. Retired after 40 years wrenching on trucks! 2010 Ford Ranger toad with bicycles or KLR 650 in the back. Easy to spot an RVer, they always walk around with a screwdriver or wrench in one hand! 
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03-12-2022, 09:36 AM
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#12
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Senior Member/RVM #90
Monaco Owners Club
Join Date: Nov 2002
Location: Columbus, MS
Posts: 54,794
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Quote:
Originally Posted by Dutch Star Don
Just remember.....diesel motorhomes don't accelerate, they gain momentum! You're also running a turbo which takes time to build power.
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YUP!  
__________________
Joe & Annette
Sometimes I sits and thinks, sometimes I just sits.....
2002 Monaco Windsor 40PBT, 2013 Honda CRV AWD
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