Results 1 to 3 of 3

Thread: Ye old 1JZ idle hunting and other short stories

  1. #1
    Forum Member 1st year Apprentice
    Join Date
    Jun 2008
    Location
    Gold Coast, Qld
    Posts
    10

    Angry Ye old 1JZ idle hunting and other short stories

    Hi all, so it appears that my 1JZ has decided to be a temperamental bitch.

    History is this:
    JZX90 factory manual half cut into MX83 12 years ago, running factory ECU, AFC NEO, FCD, stock everything else. Car was written off 6 years ago (thanks little bro) while I was living overseas and sat for nearly 5 years before I moved back and put it back on the road after a re-shell.

    Replaced all the caps in the ECU about 7 years ago, CTS around the same time, coil packs too. Haven't replaced the O2, TPS, MAP sensor, or ISCV.

    It's been back on the road for a month, and I'm having a weird issue with the idle now and then. I can start the car up and it will idle perfectly, then the next time I start it the thing will rev up to 2k for a bit then start hunting between 1k and 2.5k. This seems to happen daily to me. I start it in the morning and it will idle high while it's cold, then come down to around 700, drive it to work and park it. Get in at lunch time and start then it starts it's bullshit idle hunt, drive to where I need to go, shut it down, start it 5 minutes later and it's fine.

    For about a week it didn't do it, then the other day it decided to start doing it again. Pulled off the ISCV and cleaned it (found a vac leak which I fixed in the process), reset the ECU and did a re-learn. This was fun as it didn't want to idle over 400 during the first 50Kms or so. After this it's also decided that some days it doesn't want to start until after I tried cranking it 4 or 5 times (that's 4 or 5 times turning the key off and back to start).

    I checked the output of the O2 sensor, it's fine and fluctuating between .2 and .7/8 at idle. I'm going to check the TPS is calibrated correctly, but I'm starting to think that this may be the cause of my woes as the only thing that stops it fluctuating (when it's playing up) is when I unplug the TPS. This causes the idle to shoot up to about 2.5K and not come down.

    When I'm driving it while it's playing up, the throttle response is weird. I'll dab the throttle and it will lurch forward (bringing the revs up substantially), and when I back off there is about a half to 1 second delay before it actually decides to decel.

    I'd love to be able to rip out the factory ECU and go standalone but I can't afford that at the moment. I'm also going to pull the ECU out again and check it over to see if there is any corrosion on the board or if any of the replacement caps have decided to start dying. I pulled out my spare ECU (JZZ30) to try last night, but it looks like it's had a bath and is corroded inside.

    Any thoughts?

  2. #2
    Junior Member Backyard Mechanic
    Join Date
    Jan 2010
    Location
    Western Australia
    Posts
    242

    Default Re: Ye old 1JZ idle hunting and other short stories

    You can ignore the O2 sensor as its not a factor at idle (only used during part throttle, off boost cruise by stock ECU)
    Sounds like either the TPS isn't giving a consistent IDL signal or the re-capped ECU may have another dodgy capacitor or have damage to one of the tracks on the PCB...I'd start with TPS as its easier, check adjustment, IDL signal etc fist, then have a close look at the ECU...

  3. #3
    Forum Member 1st year Apprentice
    Join Date
    Jun 2008
    Location
    Gold Coast, Qld
    Posts
    10

    Default Re: Ye old 1JZ idle hunting and other short stories

    Yeah ended up checking the caps last night, the main one that sits on the B+ power rail had dropped the arse out of it.

    Changed it and it seems better so far but will know more over the coming days etc.

Similar Threads

  1. Help! 1G-FE VVTI idle issue, keeps hunting
    By headake in forum Tech and Conversions
    Replies: 3
    Last Post: 23-04-2014, 01:58 PM
  2. AE95 hunting for idle
    By PrettyCoolWagon in forum Tech and Conversions
    Replies: 6
    Last Post: 21-02-2011, 05:25 PM
  3. Hunting at idle.
    By boshy in forum Tech and Conversions
    Replies: 3
    Last Post: 09-06-2009, 05:19 PM
  4. 4AGE 16V - Idle Hunting
    By Tom4AGE in forum Tech and Conversions
    Replies: 26
    Last Post: 11-07-2008, 06:30 AM

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •