Author Topic: Question, what exactly does engine % load mean?  (Read 935 times)

Jimmy Garcia

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Question, what exactly does engine % load mean?
« on: January 25, 2022, 04:15:34 AM »
Good day,
I been doing some searching on the forum and google and am curious about the Aladdin reporting engine percent load.  I have only seen it maxed out at 49 percent.  No matter what my configuration towing or slick.  I do not think I have power issues as it seems to move along.  On flat ground it indicates prob 20 give or take.  When I climb a grade the most I see is 49.   Even with the transmission shifting.  Does this mean that the engine is only giving 49 percent power.  Does it mean that the engine has 51 percent to give?  I have an 06 Monterey with C9 cat.  Temps and systems seem to be holding within norms.  Thanks for the expertise.  Have a pleasant day.  Cheers. 
2006 Monterey
C9 400 HP

Eric Maclean

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Re: Question, what exactly does engine % load mean?
« Reply #1 on: January 25, 2022, 02:29:18 PM »
Jimmy
The percent load is a calculated figure that the engines ECM generates using the ECM inputs like throttle position sensor , manifold pressure sensor RPM, etc , this is actually a percentage of the engines maximum torque output rating and in some cases is used by the transmission control system to modify the shift pattern.

In most cases the percent load should be near 95 to 98 % at wide open throttle while climbing .
My 3126 will run 98% climbing and anywhere from 30;to 60% on flat or semi flat ground dependant on throttle input.

If you don't notice any lack of power I would question the validity of the percent load figure however the Aladin only shows what engine ECM communicates to it meaning that figure if incorrect is a function of the engine ECM.

This is a question that might better be addressed by Dave Atherton

Hope this helps
Eric
« Last Edit: January 25, 2022, 03:58:35 PM by Eric Maclean »
1997 Patriot Yorktown
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2009 Chevy HHR
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Steve Huber Co-Admin

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Re: Question, what exactly does engine % load mean?
« Reply #2 on: January 25, 2022, 02:53:14 PM »
Jimmy,
Climbing a grade with a 400 hp C9 you should be seeing over 49%. My guess is that the Alladin is the culprit based on your info as to engine performance.
Steve
Steve
2015-          07 Contessa Bayshore C9,  400 hp
2013-2015: 00 Marquis Tourmaline, C12, 425 hp
2005-2013: 01 Contessa Naples, 3126B, 330 hp

Scott Shearer

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Re: Question, what exactly does engine % load mean?
« Reply #3 on: January 25, 2022, 07:13:08 PM »
Jimmy,

The Percent Load on our Aladdin also pegs at 49%. At first, I thought that this might be a sign that the Aladdin system was failing, but I think it is actually a bug.

A couple years ago I started using the Silverleaf VMSpc system to report engine data and it appears to correctly report engine load, I see 100% load while the Aladdin system is pegged at 49%. In fact, the Aladdin reading is usually about ½ that of the VMSpc reading.

Don’t know for sure, but this bug may have been introduced in 2006 when Monaco started using J1939 protocol to report engine data. The Aladdin control module (VCM) only knows J1587 protocol and doesn’t understand J1939, so a protocol translator (J1939 Bridge) was incorporated into the system. On your coach, I believe that the J1939 Bridge is located in the front run box.

In 2007ish, Monaco started using the Medallion instrument cluster that reads native J1939.

-Scott
Scott & Susie Shearer
2006 Patriot Thunder
Lexington IV 40'
Cat C13
2015 JKU Hard Rock
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Jimmy Garcia

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Re: Question, what exactly does engine % load mean?
« Reply #4 on: January 26, 2022, 09:01:56 AM »
Thanks everyone.  You all are a great resource.  I dont seem to suffer for power.  On the flat the coach will get up over 65 if I am not paying attention.  On hills well I can pass semis.  I am guessing the bug theory may be likely.  The engine runs good.  Had full diagnostics and oil analysis everything checked good.  I just found it strange.  I think I will have to just double the value for now.  Thanks so much.
2006 Monterey
C9 400 HP

Jimmy Garcia

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Re: Question, what exactly does engine % load mean?
« Reply #5 on: January 26, 2022, 09:05:43 AM »
Jimmy,

The Percent Load on our Aladdin also pegs at 49%. At first, I thought that this might be a sign that the Aladdin system was failing, but I think it is actually a bug.

A couple years ago I started using the Silverleaf VMSpc system to report engine data and it appears to correctly report engine load, I see 100% load while the Aladdin system is pegged at 49%. In fact, the Aladdin reading is usually about ½ that of the VMSpc reading.

Don’t know for sure, but this bug may have been introduced in 2006 when Monaco started using J1939 protocol to report engine data. The Aladdin control module (VCM) only knows J1587 protocol and doesn’t understand J1939, so a protocol translator (J1939 Bridge) was incorporated into the system. On your coach, I believe that the J1939 Bridge is located in the front run box.

In 2007ish, Monaco started using the Medallion instrument cluster that reads native J1939.

-Scott

Good day Scott.
So is that Bridge a plug and play fix to have accurate engine data?  Thanks again.
2006 Monterey
C9 400 HP

Scott Shearer

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Re: Question, what exactly does engine % load mean?
« Reply #6 on: January 26, 2022, 04:37:45 PM »
Jimmy,

I don’t think replacing the Bridge module would fix the problem...and replacement Bridge could be hard to find, I’ve seen them on eBay and some of the salvage yard sites and they are rather expensive.

If there actually is a bug it’s likely in the Aladdin control module (VCM). It also could be that our coaches have the wrong version of the VCM.

Of the engine parameters that I’ve compared, all others match between the Aladdin and VMSpc.

-Scott
Scott & Susie Shearer
2006 Patriot Thunder
Lexington IV 40'
Cat C13
2015 JKU Hard Rock
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Jimmy Garcia

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Re: Question, what exactly does engine % load mean?
« Reply #7 on: January 27, 2022, 02:10:35 AM »
Jimmy,

I don’t think replacing the Bridge module would fix the problem...and replacement Bridge could be hard to find, I’ve seen them on eBay and some of the salvage yard sites and they are rather expensive.

If there actually is a bug it’s likely in the Aladdin control module (VCM). It also could be that our coaches have the wrong version of the VCM.

Of the engine parameters that I’ve compared, all others match between the Aladdin and VMSpc.

-Scott

Scott,
Thanks for that.  Looks like there be no updates to the code and will have to live with simple math.  Thanks again.
2006 Monterey
C9 400 HP

Dave Atherton

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Re: Question, what exactly does engine % load mean?
« Reply #8 on: January 27, 2022, 06:15:19 AM »
Gentlemen, aftermarket equipment problems. I’m not a fan of using aftermarket add on equipment,
location connection point within Caterpillar ET diagnostic engine test port of which I have expressed
My thoughts several times. If everything is working fine there is no problem reading deeper in above
post possible aftermarket code reader is giving out incorrect data. Yes we have experienced before
engine ECM failure for this reason and again the data port was not meant to be used for attachments>

Reading on and the percent of engine power is programmed into the engine ECM as Eric stated come
from several factors. One thing certain information is not available for these aftermarket attachments.
Several of the beaver member have had Caterpillar ET readout engine ECM data and printout. Looking
at the printout you will note several entries in percentage of which will answer the first question, in
most cases percent of load depending on which engine we are talking about will fall into area 34 to 46
Percent. Same time fuel milage will run between 6 and 9 mpg, the engine throttle position sensor is
set between 3 to 5 percent of which all motorhomes will be 3 percent,  the reason for setting of 3 percent is engine low idle at 700 rpms, high idle on throttle position sensor is 95 percent. This should
give you some idea correct values using OEM diagnostic equipment. Sometimes From a technician
stand point information that is incorrect can lead a person into a rabbit hole looking at what is correct.
The answer is the builder of the engine has the correct technical information. Dave Atherton Retired Cat
Mechanic
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