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Erratic engine revs with AC on?

Discussion in 'Technical Chat' started by trdferguson, Aug 15, 2009.

  1. Aug 15, 2009 at 11:20 AM
    #1
    trdferguson

    trdferguson [OP] Active Member

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    Hey you'll. I just picked up my first taco EVER! Its also my first truck ever; I'm lovin' it. So here is the deal: The truck idles just fine and drives just fine when the AC isn't on. But when I turn it on, I notice at idle and while I'm driving that the engine will rev up about 500 RPM for a few seconds, then go back down. And this happens the entire time the AC is on, as soon as I turn it off, the erratic revving stops. Whats the deal? And my AC stays cold, it doesn't fluctuate in temp, its not like the condensor keeps cutting on then off...I have a 2k8 Tacoma V6 TRD Sport DC/SB 30k miles

    If this is a double post my B, I did a search and couldn't find anything relating to the topic. Thanks in advance
     
  2. Aug 15, 2009 at 11:59 AM
    #2
    chris4x4

    chris4x4 With sufficient thrust, pigs fly just fine. Moderator

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    FlimFlubberJAM
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    The RPM's shouldnt fluctuate that much. Maybe a couple hundred RPM, but I think 500 rpm may be much.
     
  3. Aug 15, 2009 at 12:10 PM
    #3
    vtragweed

    vtragweed Beef Slut

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    afe pro-dry s filter, LCE headers, painted black steelies,color matched grill surround, URD short shifter, UWS black tool box
    that sounds a lil extreme, i would have that sucka checked out
     
  4. Aug 16, 2009 at 6:32 AM
    #4
    Janster

    Janster Old & Forgetful

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    According to my scangauge.... without A/C on... Just sitting at a light or sitting in a drive-thru, my truck fluctuates between 500-670ish RPM's. It'll rev up to 670ish for about 30 seconds. Drop down to 500ish for 30 seconds. It'll keep doing that while I'm sitting there.

    Without the exhaust, I couldn't hear it and it was a non-issue (out of sight out of mind). And with the scangauge, I can actually see the numbers.

    I'm pretty sure it's normal and just the way these trucks are. This could also be another reason for the Automatic lurch also.
     
  5. Aug 16, 2009 at 7:04 AM
    #5
    98tacoma27

    98tacoma27 is gooder 'en chicken Moderator

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    Very interesting. I wonder if its an energy saving feature.
     
  6. Aug 17, 2009 at 4:26 PM
    #6
    trdferguson

    trdferguson [OP] Active Member

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    Hmm after looking at it closer it is more like 250 RPMs it jumps up for about 20 seconds or so, then it drops. But its not just at idle, its while driving too; is that normal too? Thanks again
     
  7. Aug 17, 2009 at 4:27 PM
    #7
    chris4x4

    chris4x4 With sufficient thrust, pigs fly just fine. Moderator

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    Sounds normal to me. Mine seems to vary a couple hundred RPM when the AC is on...
     
  8. Aug 18, 2009 at 8:44 AM
    #8
    trdferguson

    trdferguson [OP] Active Member

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    Sweet. Thanks for the help
     
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