1st Generation Dodge Cummins 89-93 Discussion of 12 Valve 5.9 Liter Dodge Cummins Diesels with Rotary Injection Pumps

Idle question!

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Old 07-11-2010, 09:29 PM
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Ok, when you have your air conditioner on, shouldnt the engine idle up some to compensate? If so,, why wouldnt it do this if its supposed to? If it isnt supposed to
then never mind, cuz mine dont idle up. It does idle back up when I switch it off though.
Any one know?
 
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Old 07-11-2010, 09:59 PM
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mine does not idle up either
 
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Old 07-12-2010, 12:13 AM
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mine dont do it either
the AC dont draw that much at idle anyway
 
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Old 07-12-2010, 12:37 AM
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it shouldnt go up on a mechanical engine. there is no computers controlling all the injection and everything to realize the draw and compensate. maybe on a newer computer controlled vehicle it will but not on a first gen
 
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Old 07-12-2010, 06:45 AM
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Ah, yeah thats true. Well maybe I need to set my idle up a tad. I dunno.
 
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Old 07-12-2010, 11:00 AM
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Originally Posted by tltruckparts
it shouldnt go up on a mechanical engine. there is no computers controlling all the injection and everything to realize the draw and compensate. maybe on a newer computer controlled vehicle it will but not on a first gen
x2. On my 98.5 the rpm is compensated for the load but not on my 93.

---AutoMerged DoublePost---

Originally Posted by Mudbug
Ah, yeah thats true. Well maybe I need to set my idle up a tad. I dunno.
Why? And besides, the idle set screw is an absoulte b%&*h to get to!
 

Last edited by KD93; 07-12-2010 at 11:00 AM. Reason: Automerged Doublepost
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Old 07-12-2010, 12:00 PM
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Originally Posted by KD93
x2. On my 98.5 the rpm is compensated for the load but not on my 93.

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Why? And besides, the idle set screw is an absoulte b%&*h to get to!
Well when its in drive or with the air conditioner on it drops down to 500 rpm and
doesnt seem that smooth to me, feels like it vibrates more at low rpm. The truck that is..
 
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Old 07-12-2010, 12:51 PM
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I can barely even tell the AC is running in mine.. it doesn't really load the motor at all
 
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Old 07-12-2010, 04:51 PM
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I think it will load it more if you are running R-134a instead of R-12 if its and R-12 system. IDK for sure but mine drops a lot with the A/C on too
 
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Old 07-12-2010, 04:55 PM
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seems highly unlikely to me that the type of freon or refrigerant used would change the "load" on the engine. my idle doesn't change whether A/C is on or off. and, mine was retrofitted with R-134a. at most, i might hear a slight increase in idle when the A/C is switched off. but, if it does increase, it may only be by 25RPM which isn't enough to see on the tach.
 


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