Analytics Made Easy - Statcounter
Idle speed increase. - Engine/Ancilliaries - TLF - Totally Lotus Jump to content


Idle speed increase.


Recommended Posts



I've spend ages tracking down vacuum leaks on my 1989 SE Turbo project.  It will idle reasonably well with a little bit of popping, but the revs kick up to about 2000.  Blipping the throttle brings it down to about 1200 - 1300, but after a few seconds the revs jump up again.  Obviously something is tripping in.  I have a code 26 that I still haven't managed to clear, but have blanked off the hose from the charcoal canister, so there is not air in leak from there. I'm not sure anything else code 26 related would affect the idle.


I have 'pressure tested' the inlet as the manual recommends with soapy water to find any more leaks and I think I have got them all.  Any ideas?


Many thanks



Link to comment
Share on other sites

  • Replies 2
  • Created
  • Last Reply

Top Posters In This Topic

Popular Days

Top Posters In This Topic

Do you still have the throttle jack connected physically, and to the solenoid (electrically and vacumm)?


It could be several things.

The Code 26 could be relatedm could be the rpm relay or the throttle jack.


The EMH manual has a section for troubleshooting a high idle.


Throttle sticking shaft or binding linkage. This will cause a high TPS voltage (open throttle indication) and the  ECM will
ECM will not control idle. TPS voltage should be about 0.45 to 0.70 volt with the throttle closed.
IAC valve will not move if voltage is below 9 volts or greater than 17.8 volts.
Also check battery cables and ground straps for poor contact. Erratic voltage will cause the IAC valve to change its position,
resulting in poor idle quality.
Those are just some.
Can you log freescan data and send it to me?
If you record freescan data, do it this way.

start with a cold engine.
connect the laptop and get freescan running.
turn on the ignition but don't start the car.
start logging the .csv in freescan
start the engine
don't touch the throttle at any time!
let the car idle until it is warm, up to 82C coolant temp.
allow IAC counts in freescan data page to stabilize.
Take it for a drive try to replicate issue, get full boost and 100% throttle if possible, use all 5 gear, don't lug engine.

save data.


Vulcan Grey 89SE


Link to comment
Share on other sites





2 Freescan logs attached.  The first is up to the point where freescan froze and the second is from when I restarted freescan (for some reason my PC can't cope with start up too well)


I let it run up to temp without touching the throttle and it ran reasonably well but fast.  It was gradually slowing down but after a few minutes kicked up from 1600 to >2000 (on rev counter).  Once up to temp I blipped the throttle a couple of times which brought the revs down for a few seconds then it kicked back up again.


TPS, IAC and O2 sensor all new.


No throttle jack (it must have been removed before I got it) Vac hoses looped out and solenoid still in place.


Unfortunately I can't take it for a run as I have no brakes at the moment (Its a project car)


Man thanks for you help




freescan10 octv1.csv


Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

  • Create New...

Important Information

We use cookies to enhance your browsing experience, serve personalized ads or content, and analyze our traffic. By clicking " I Accept ", you consent to our use of cookies. We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.