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09-29-2018, 07:06 PM
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#1
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Senior Member
Holiday Rambler Owners Club
Join Date: Aug 2016
Location: Bonney Lake, WA
Posts: 165
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Wandering Turbo Boost Pressure
2009 HR Scepter with Cummins 425 ISL power plant
Usually, under normal driving conditions, my boost pressure max's out at 30-32 PSI when I've got the accelerator floored and climbing a hill. Today, we did some higher elevation driving from Salt Lake City to Torrey, Utah where a couple of passes were on the order of 8,500' MSL.
I noticed that the boost pressure under max power conditions was wandering between 30-24-22-28-30 PSI at random. I did not notice any other instability in RPMs, etc. Could it just be an indication issue? Loose hose? A hole in a hose? Turbo going bad?
Hard to tell if climbing performance was affected as it was our first time towing with a dolly and minivan. Should I expect a mushy climb at altitude?
I do have a ScanGaugeD and will try to find a page that gives any turbo info. Meanwhile, any thoughts?
__________________
Barry and Della from Bonney Lake, WA
2009 HR Scepter 42KFQ
Toad is a modified 2005 Chrysler Town and Country
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09-29-2018, 07:22 PM
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#2
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Senior Member
Fleetwood Owners Club Freightliner Owners Club Spartan Chassis
Join Date: Nov 2009
Location: FORT WORTH, TEXAS
Posts: 2,752
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That sounds about right. Electronic engines are constantly changing.
Bill
__________________
2008 Newmar Mountain Aire
450 HP Cummins ISM 4000MH Allison Trans.
Towing a 2014 Honda CRV with a Blue Ox tow bar.
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09-29-2018, 09:40 PM
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#3
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Senior Member
Monaco Owners Club
Join Date: May 2015
Location: Where I happen to land
Posts: 2,529
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Quote:
Originally Posted by WILDEBILL308
That sounds about right. Electronic engines are constantly changing.
Bill
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I agree. Mine, though a Cat, just had a turbo fail. 40 psi under load and no power.
Prior I saw the boost fluctuate widely. Depending upon the load, grade, etc.
__________________
John and Debi
2008 Beaver Contessa, 2005 Jeep Grand Cherokee,
28 years retired Fire Captain Tales of the Muttley Crew
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09-29-2018, 09:51 PM
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#4
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Senior Member
Country Coach Owners Club Solo Rvers Club iRV2 No Limits Club
Join Date: May 2011
Location: Vancouver, WA
Posts: 37,725
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On some engines like my ISX the EGR closes at about 7,500 feet which might affect boost pressure.
__________________
2009 45' Magna 630 w/Cummins ISX 650 HP/1950 Lbs Ft, HWH Active Air
Charter Good Sam Lifetime Member, FMCA,
RV'ing since 1957, NRA Benefactor Life, towing '21 Jeep JLU Rubicon Ecodiesel
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09-29-2018, 11:56 PM
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#5
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Senior Member
Monaco Owners Club
Join Date: May 2015
Location: Where I happen to land
Posts: 2,529
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Quote:
Originally Posted by Captjake1
I agree. Mine, though a Cat, just had a turbo fail. 40 psi under load and no power.
Prior I saw the boost fluctuate widely. Depending upon the load, grade, etc.
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I should clarify. I saw no issues with the fluctuation in pressures. Only when it went excessive on the boost pressure.
__________________
John and Debi
2008 Beaver Contessa, 2005 Jeep Grand Cherokee,
28 years retired Fire Captain Tales of the Muttley Crew
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09-30-2018, 02:21 AM
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#6
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Senior Member
Join Date: Jul 2014
Posts: 35,442
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Change the fuel filters, if not done recently.
Low fuel supply, low boost pressures.
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09-30-2018, 04:18 AM
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#7
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Senior Member
Monaco Owners Club
Join Date: Aug 2017
Location: Orlando, Florida
Posts: 5,819
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Quote:
Originally Posted by Captjake1
I agree. Mine, though a Cat, just had a turbo fail. 40 psi under load and no power.
Prior I saw the boost fluctuate widely. Depending upon the load, grade, etc.
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40 psi is normal boost for some CAT engines (like my 2005 C13).
Can you provide more detail? What failed in the Turbo? Bearing/seal?
Are you saying you were getting 40 psi boost AND the turbo had also failed at that time?
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09-30-2018, 04:25 AM
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#8
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Senior Member
Newmar Owners Club
Join Date: Oct 2009
Posts: 10,310
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Quote:
Originally Posted by Barryc737
2009 HR Scepter with Cummins 425 ISL power plant
Usually, under normal driving conditions, my boost pressure max's out at 30-32 PSI when I've got the accelerator floored and climbing a hill. Today, we did some higher elevation driving from Salt Lake City to Torrey, Utah where a couple of passes were on the order of 8,500' MSL.
I noticed that the boost pressure under max power conditions was wandering between 30-24-22-28-30 PSI at random. I did not notice any other instability in RPMs, etc. Could it just be an indication issue? Loose hose? A hole in a hose? Turbo going bad?
Hard to tell if climbing performance was affected as it was our first time towing with a dolly and minivan. Should I expect a mushy climb at altitude?
I do have a ScanGaugeD and will try to find a page that gives any turbo info. Meanwhile, any thoughts?
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You can set your Scan Gauge D for boost, and it will come right off the ECM, and more stable reading than a dash gauge. Did this just start to happen?, if so I would check all the connection's on the air filter system and to the charge air cooler. Even the Charge Air Cooler might have a small leak......
__________________
2012 Essex 4544 2011 Jeep JK, M&G Braking, 2014 MTI 27' Hog Hauler, Wireless brake control, 2006 Ultra & 1989 Springer, 2003 Harley-Davidson
FLHR Road King Anniversary
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09-30-2018, 09:16 AM
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#9
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Senior Member
Monaco Owners Club
Join Date: May 2015
Location: Where I happen to land
Posts: 2,529
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Quote:
Originally Posted by CountryB
40 psi is normal boost for some CAT engines (like my 2005 C13).
Can you provide more detail? What failed in the Turbo? Bearing/seal?
Are you saying you were getting 40 psi boost AND the turbo had also failed at that time?
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Highest on mine is 29 normally. Noticed loss of power and the boost wrapped right up to 40. It is a variable vane turbo. Scanning with computer showed that the vane were not moving. Only common (I am told) with the vvt turbo.
__________________
John and Debi
2008 Beaver Contessa, 2005 Jeep Grand Cherokee,
28 years retired Fire Captain Tales of the Muttley Crew
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09-30-2018, 10:50 AM
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#10
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Senior Member
Monaco Owners Club
Join Date: Aug 2007
Location: Gardnerville, Nevada
Posts: 1,336
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Quote:
Originally Posted by Captjake1
Highest on mine is 29 normally. Noticed loss of power and the boost wrapped right up to 40. It is a variable vane turbo. Scanning with computer showed that the vane were not moving. Only common (I am told) with the vvt turbo.
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That's a bummer.
__________________
Ken, Chris and Maverick (Golden Retriever)
2009 Beaver Contessa
1984 LS1 CJ7 & 2017 Yamaha YXZ SS SE
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10-01-2018, 10:31 AM
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#11
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Senior Member
Monaco Owners Club
Join Date: Jan 2016
Location: Fresno, CA
Posts: 131
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I too am having boost pressure issues so very interested in this discussion.
This post on an older coach and therefore turbo, may be of interest:
http://www.irv2.com/forums/f123/low-...isl-93510.html
When monitoring this, is your PacBrake/exhaust break on? (turn off temporarily, to take it out of the scenario)
Not sure if you have an EGR, but this could be affecting steadystate conditions.
Are you in Economy mode while this is happening?
__________________
Rich and Lyn
2006 Monaco Camelot 40 PDQ, 2014 Outback
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10-01-2018, 01:45 PM
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#12
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Senior Member
Texas Boomers Club Holiday Rambler Owners Club
Join Date: Jun 2002
Location: What? Like right now? ;-)
Posts: 1,302
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Quote:
Originally Posted by Captjake1
Highest on mine is 29 normally. Noticed loss of power and the boost wrapped right up to 40. It is a variable vane turbo. Scanning with computer showed that the vane were not moving. Only common (I am told) with the vvt turbo.
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The fix for carbon and soot buildup on ISB-6.7 VVT cummins is to drill a hole in the housing and fog with solvent. Not sure if its done while running or not. But it doesnt sound real good to me. G/L..
I like my wastegated old school turbo ;-)
__________________
2003 Scepter 40PDBB - Roadmaster RR8S - Cummins ISC350 - purch aug16
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10-01-2018, 01:57 PM
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#13
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Senior Member
Newmar Owners Club
Join Date: Oct 2009
Posts: 10,310
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Quote:
Originally Posted by jimmy braden
The fix for carbon and soot buildup on ISB-6.7 VVT cummins is to drill a hole in the housing and fog with solvent. Not sure if its done while running or not. But it doesnt sound real good to me. G/L..
I like my wastegated old school turbo ;-)
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What do ya do with the hole then?
Solvents have a high flash point ......does not sound like a good idea ......
__________________
2012 Essex 4544 2011 Jeep JK, M&G Braking, 2014 MTI 27' Hog Hauler, Wireless brake control, 2006 Ultra & 1989 Springer, 2003 Harley-Davidson
FLHR Road King Anniversary
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10-01-2018, 01:59 PM
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#14
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Senior Member
Texas Boomers Club Holiday Rambler Owners Club
Join Date: Jun 2002
Location: What? Like right now? ;-)
Posts: 1,302
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Plugged with a brass pipe fitting I think
__________________
2003 Scepter 40PDBB - Roadmaster RR8S - Cummins ISC350 - purch aug16
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