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3rz-fe high idle/surge/hard start

Discussion in '1st Gen. Tacomas (1995-2004)' started by Kwik213, May 12, 2025.

  1. May 12, 2025 at 7:11 PM
    #1
    Kwik213

    Kwik213 [OP] New Member

    Joined:
    May 12, 2025
    Member:
    #471083
    Messages:
    1
    Gender:
    Male
    Vehicle:
    2002 Tacoma black 2.7l 4x4 5 speed
    2.5 front lift 2.0 rear lift
    IMG_6137.jpg IMG_6166.jpg Hey all, I recently replaced my old and tired 3rz-fe for a lower mileage one. but I’m having trouble since with a high idle (2000 rpms) an idle surge (1500-2000) and a really hard cold start have to hold foot to the floor sounds like a lawn tractor when it does start and keep it floored till it works through the misfires and stuff and comes to a smooth idle at 1500 rpm and slowly rises stopping at 2000 rpm. Once up to temp starts fine but same problem after about 4-5 hours of sitting I had a code for engine coolant temp sensor and I remember reading forums about it before causing similar issues well wouldn’t you know I never plugged it in lol plugged in cleared codes (left battery unhooked for 5 mins with headlights on) code didn’t persist but the issue did

    I’ve been told by a friend the vacuum for the front differential could’ve gotten unhooked when the old motor was removed and new one was installed but as far as I can tell every vacuum line is on and connected. The new motor also was known running with no CELS in the parts truck I pulled it out of.

    so my question stands how can this engine run perfect last weekend and like this the following weekend? With no CEL’s Makes no sense to me.

    truck info:
    2002 sr5 Tacoma xtra cab with ac
    3rz-Fe 2.7L engine
    5 speed manual
    4 wheel drive (floor/jshift)
     
  2. May 12, 2025 at 8:27 PM
    #2
    Glamisman

    Glamisman Well-Known Member

    Joined:
    Oct 22, 2016
    Member:
    #200436
    Messages:
    4,896
    Gender:
    Male
    First thing is check your grounds, there is one off the back of the head to the firewall, one off the battery to the D/S inner fender well and a gang ground on the motor for all of the PCM/EFI connections. With your scan tool verify your engine coolant temp (ECT) and see if it is accurate. If the motor is cold and it is 75* outside your ECT should be very close to that, a reading -40* means you have a bad/open ECT. Check your other sensor readings too. After she is warmed up check to see if she has gone into closed loop mode.

    Major jobs like this means that every connector has been unpluged and repluged, pins push out, wires get broken, things get hooked up wrong.
     

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