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Thread: Troubleshooting: Running hot > hanging throttle + wanting to stall

  1. #1
    Join Date
    May 2018
    Location
    Albany, NY
    Posts
    347

    Default Troubleshooting: Running hot > hanging throttle + wanting to stall

    I'll appreciate any help I can get on the matter but this is more of a way to me to drop things down in one place and keep the thought flow going. Maybe see if anybody else has similar issues

    This left me temporarily stranded and having to push the car uphill at night on the highway, so I hope nobody will have to go through the same thing as me in the future.

    I have trapped air problems in the over flow like others do

    see
    http://www.usa7s.net/vb/showthread.p...tank-do-I-have

    This could potentially lead to a head gasket, which is something on the pending list.


    Problem:

    Car runs fine. Car idles for a while/gets stuck in traffic and starts to run hotter. From dead middle at 80 to creeping into 100 degrees or so.

    At the same time throttle starts to hang a lot more and as of yesterday even started bouncing off the rev limiter with no further input. "run away revving" if you will.

    While the running hot is an issue of its own, rev hang/acceleration is more of a problem.

    Comments
    • Pedal is coming back without an issue
    • I've added extra springs to my ITBs to help the return
    • I've adjusted the feed of the throttle cable to give it max slack possible
    • The throttle problem seems to only happen once it starts to run hot and doesn't happen throughout the entire "running hot" period. Seems to happen and then go away/diminish as I continue on my trip
    • TWM ITB's have never been serviced officially but have been taken apart and inspected during last event of working on the motor
    • Sudden throttle snapping back has had varied success in the hanging throttle event. Sometimes it works, sometimes it doesn't
    • As the car is having the running hot event, it occasionally wants to slowly sputter and stall at idle. Giving it mild throttle helps


    Things that have been measured/tested
    • ITB's flow has been tested. 3 are pretty matching at "7" at idle on the meter. One at "9"
    • Compression test was good
    • Leak down test was good
    • Exhaust gasses contamination in coolant was a pass
    • Disconnected the IAC hose to see if that causes a run away situation. My revs went to 3500 and stayed there. No run away event


    Things to look at still
    • Inspect the butterflies carefully
    • Consider TPS being an issue
    • Would eliminating running hot solve my problem? > Do water pump/head gasket


    Questions with no answers
    • Why is running hot causing the throttle issue > which parts could the heat be effecting
    • Why is running hot causing the car wanting to stall/fail to maintain idle?
    • Why does the issue seem to diminish/go away with time even if running hot
    • What caused the recent run away/bouncing off the rev limiter event?
    • What is causing the revs to hang/even accelerate without an input from the throttle?
    2001 Caterham Superlight R

  2. #2
    Join Date
    May 2018
    Location
    Albany, NY
    Posts
    347

    Default

    Since everybody likes pictures

    This problem was part of chain of problems that left me stranded yesterday.

    Car was running hot at idle at rest area

    Revs were starting to be a little hangy but I thought it would be fine

    Get on the highway just to have a run away rev situation with revs bouncing off rev limiter

    Pull over and shut the car off.

    Go to restart the car just to have immedeate full loss of electrical power. Taking out the hazards, at night. Convenient.

    Had to push the car back uphill to rest area to troubleshoot as I didn't feel safe on highway without hazards at night.

    Sign was very appropriate




    Sent from my Pixel 3a XL using Tapatalk
    2001 Caterham Superlight R

  3. #3
    Join Date
    Jan 2020
    Posts
    147

    Default

    Oh man, sorry, not fun.

    This doesn't explain all of the symptoms, especially the racing idle, but have you considered that perhaps you are suffering vapor lock?
    Last edited by Pokey; 07-29-2020 at 09:04 PM.
    Greg

  4. #4
    Join Date
    Jun 2013
    Location
    N. California
    Posts
    112

    Default

    My vote is a loose butterfly or misaligned linkage. Please don't drive it until it's sorted! A 7 stuck at WOT is not a good place to be.

    Edit/Addition:
    Is your throttle cable near a heat source (exhaust)? I've seen the plastic inner lining of some cables get soft and grab the inner cable leading to a "gummy" feel.
    Last edited by ashyers; 07-30-2020 at 08:43 AM.

  5. #5
    Join Date
    Feb 2009
    Location
    NYC
    Posts
    5,016

    Default

    Sorry to see this one Vlad. Bit a weird bunch of symptoms. Throttle linkage or throttle bodies would be revs situation. Did your alternator stop working and you had been on battery all the time - hence the electrical meltdown?
    Mike
    2010 Caterham CSR with Cosworth 2.3 Duratec
    2018 Caterham 420R with 2L Duratec 210hp at Donington UK
    1975 BMW CSL Group 4 (restoration finished - track set up time)
    1977 Holden Torana "A9X" (awaiting restoration)
    1985 Holden Commodore SS Group A (suspension restoration)
    1985 Holden Commodore Group A (suspension set up)
    1982 Ferrari 400i (radiator replacement)
    1965 Ford Mustang Fastback "Holman Moody"
    1992 Ford Escort RS Cosworth WRC (dyno time)
    1990 Range Rover 2 door Classic
    and another project car coming....

  6. #6
    Join Date
    May 2018
    Location
    Albany, NY
    Posts
    347

    Default

    Quote Originally Posted by Croc View Post
    Sorry to see this one Vlad. Bit a weird bunch of symptoms. Throttle linkage or throttle bodies would be revs situation. Did your alternator stop working and you had been on battery all the time - hence the electrical meltdown?
    Electrical meltdown was due to battery losing ground.

    Disconnecting and reconnecting the terminals got me power back and allowed me to troubleshoot further that day.

    I'm thinking of disconnecting cable entirely at the bodies next time I catch the issue at home or elsewhere convenient to help partition out cable entirely.
    2001 Caterham Superlight R

  7. #7
    Join Date
    Feb 2012
    Location
    Roswell GA
    Posts
    1,004

    Default

    Does the ECU store run data?
    Life happens while you're making other plans
    1995 Caterham Crossflow RHD
    1990 Miata
    2007 GMC Sierra WT
    2013 Mini (Her's)
    2014 Outback
    JOHN DEERE D130

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