1. Welcome to Tacoma World!

    You are currently viewing as a guest! To get full-access, you need to register for a FREE account.

    As a registered member, you’ll be able to:
    • Participate in all Tacoma discussion topics
    • Communicate privately with other Tacoma owners from around the world
    • Post your own photos in our Members Gallery
    • Access all special features of the site

Nearly impossible to start; idles rough; revs fine?

Discussion in '1st Gen. Tacomas (1995-2004)' started by deckeda, Oct 7, 2017.

  1. Oct 7, 2017 at 8:25 PM
    #1
    deckeda

    deckeda [OP] Well-Known Member

    Joined:
    Aug 18, 2015
    Member:
    #162133
    Messages:
    392
    Vehicle:
    '04 Double Cab PreRunner SR5
    Took forever to crank over today. Seemed like no spark, or only a couple cylinders firing. Eventually it started but idled roughly and a bit low on RPM. Throttle responds normally and revs just fine. I only moved it around in a parking lot and didn't attempt driving it down the road.

    No CEL, so where to begin?
     
  2. Oct 7, 2017 at 8:32 PM
    #2
    Steves104x4

    Steves104x4 Well-Known Member

    Joined:
    Apr 17, 2010
    Member:
    #35468
    Messages:
    17,260
    Gender:
    Male
    First Name:
    Steve
    Buffalo NY
    Vehicle:
    2010 RC 2.7 4x4
    BUCKLE UP! It makes it harder for Aliens to pull you out of your Truck.
    Coolant temp sensor, maybe
     
  3. Oct 7, 2017 at 9:41 PM
    #3
    deckeda

    deckeda [OP] Well-Known Member

    Joined:
    Aug 18, 2015
    Member:
    #162133
    Messages:
    392
    Vehicle:
    '04 Double Cab PreRunner SR5
    So if I can get it started, run until hot and see how it is?

    Or, once I learn where that is I suppose I could put an ohm meter on it?

    Wouldn't a bad temp sensor default to making it do the opposite? (Start fine cold but not ever tell the ECU engine hot?)
     
  4. Oct 7, 2017 at 11:39 PM
    #4
    Empty_Lord

    Empty_Lord Toyotaholic

    Joined:
    Mar 13, 2016
    Member:
    #181186
    Messages:
    28,298
    Gender:
    Male
    First Name:
    Dan
    Northwest Indiana/Chicagoland
    Vehicle:
    66 Mercedes, 93 mr2, 95,98,01,02 Tacomas, 05 Tundra + others
    Too many trucks and mods to list.. check builds
    If the ECT is reading too hot when cold its not going to richen the fuel mixture like normal. Best way to see is if you hook a scan tool up and look at your coolant temp.
    The gauge on the dash is a seperate sensor so dont rely on that.
     
    Dalandser likes this.
  5. Oct 8, 2017 at 7:37 AM
    #5
    deckeda

    deckeda [OP] Well-Known Member

    Joined:
    Aug 18, 2015
    Member:
    #162133
    Messages:
    392
    Vehicle:
    '04 Double Cab PreRunner SR5
    I don't have a scan tool. But if it's mostly likely to be a bad sensor and nothing ignition or fuel system related, I might as well just buy the sensor and get back on the road.
     
  6. Oct 8, 2017 at 8:36 AM
    #6
    deckeda

    deckeda [OP] Well-Known Member

    Joined:
    Aug 18, 2015
    Member:
    #162133
    Messages:
    392
    Vehicle:
    '04 Double Cab PreRunner SR5
    I'm also wondering, if due to the ECU being lied to by a bad sensor, why my air/fuel ratio is bad from the start (and at idle), but just off idle and at higher RPMs the ECU making bad decisions suddenly does not? See "Throttle responds normally and revs just fine" from my original post.

    It's got an IAC valve, right? I realize symptoms could be different from what I'm experiencing. High idle and such that aren't affecting me. If the rain lets up today I may try and run the engine until it warms up and/or drive it around to better assess all behavior. Again, there's no CEL.
     
  7. Oct 8, 2017 at 10:16 AM
    #7
    Steves104x4

    Steves104x4 Well-Known Member

    Joined:
    Apr 17, 2010
    Member:
    #35468
    Messages:
    17,260
    Gender:
    Male
    First Name:
    Steve
    Buffalo NY
    Vehicle:
    2010 RC 2.7 4x4
    BUCKLE UP! It makes it harder for Aliens to pull you out of your Truck.
    How many miles on the spark plugs?
     
  8. Oct 8, 2017 at 10:18 AM
    #8
    deckeda

    deckeda [OP] Well-Known Member

    Joined:
    Aug 18, 2015
    Member:
    #162133
    Messages:
    392
    Vehicle:
    '04 Double Cab PreRunner SR5
    No clue, why? Do bad plugs only make it run bad at idle or start?
     
  9. Oct 8, 2017 at 10:20 AM
    #9
    Steves104x4

    Steves104x4 Well-Known Member

    Joined:
    Apr 17, 2010
    Member:
    #35468
    Messages:
    17,260
    Gender:
    Male
    First Name:
    Steve
    Buffalo NY
    Vehicle:
    2010 RC 2.7 4x4
    BUCKLE UP! It makes it harder for Aliens to pull you out of your Truck.
    I’d start a plugs then look for vacuum leaks
     
  10. Oct 9, 2017 at 8:19 AM
    #10
    deckeda

    deckeda [OP] Well-Known Member

    Joined:
    Aug 18, 2015
    Member:
    #162133
    Messages:
    392
    Vehicle:
    '04 Double Cab PreRunner SR5
    This morning it immediately started up and ran fine, if not perfectly. The cold idle speed was low, around 500 but everything else worked as expected. After the engine was hot everything was still great and the idle, even better. Drove it around town, nailed the throttle, everything OK. Restarting was not a problem; always had plenty of power, no misfires.

    I'm ready to declare the IAC is at least dirty, if not its plunger actually having an intermittent problem engaging on some mornings.

    I'm out of town this week and will tear it down when I get back. My understanding is that there's about a gallon of antifreeze to purge, the throttle body to remove and so on.
     

Products Discussed in

To Top