[Diy_efi] 94-95 5.0 Mustang and a hanging idle...

Wed Jun 14 04:01:11 UTC 2006

Keith,

My thoughts are now perhaps turned to the TPS sensor.  I remember that on my
Mclaren motor, i had to elongate the mounting holes on the sensor just
slightly because it kept flickering between 0v and .07v at 'zero' throttle,
which kept causing my idle to surge because of the throttle pump setting
(picture tapping the throttle constantly)

I'll help you with this when i see you next (read: tomorrow morning)  but i
figured i'd post the response for the group to see / learn from.

Another thought is that we should set the idle for the minimum value (700
rpm) with the set screw and observe for vaccum leaks pre-MAF and in the rest
of the hard lines on the car -- either with propane or ultrasonically.
either way, that would cause a surge because i'm pretty sure the way most
ECM's figure the 'bump' in idle speed is a certain number of 'steps' on the
IAC.   perhaps that may be the issue, a difference in diameter of the holes
in the IAC (overall volume of airflow)

On 6/13/06, Keith Varin <keithvarin at gmail.com> wrote:
>
> I am using the TwEECer R/T system to tune my car. I just picked one up
> from
> www.promustangperformance.com however i am still new to the unit and have
> not really gotten a grasp of what settings do what. As far as adjusting
> the
> idle... I've set the idle adjustment screw so that the car runs and to
> temporaily get around the hanging idle issue i have actually unplugged the
> IAC motor. I tried replacing it, however it made no difference. Im just
> wondering why this happened after I installed  throttle body, and why it
> only reacts the way it does when it id raining out...
>
> Keith
>
> On 6/13/06, Daniel Nicoson <A6intruder at myo-p.com> wrote:
> >
> > Keith,
> >
> > What have you done to adjust the idle with the new throttle
> > body?  Normally,
> > you would disconnect the ignition spout connector, disconnect the IAC
> and
> > then manually adjust the throttle plate one "screw-turn" off
> closed.  Then
> > adjust the idle bleed screw so the engine will idle without any computer
> > help (this would be with every load off, defroster to off, lights off
> > etc.)
> >
> > Once you get it to idle like this (fully warmed up), then turn off and
> > plug
> > all back in.  See if it is better then.
> >
> > If you were tuning the computer with a TwEECer or similar device then we
> > could do more but if you are not modifying computer settings, not much
> > else
> > you can do.
> >
> > HTH,
> >
> > Dan Nicoson
> >
> > -----Original Message-----
> > From: diy_efi-bounces at diy-efi.org [mailto:diy_efi-bounces at diy-efi.org]On
> > Behalf Of Keith Varin
> > Sent: Tuesday, June 13, 2006 10:08 PM
> > To: Diy_efi at diy-efi.org
> > Subject: [Diy_efi] 94-95 5.0 Mustang and a hanging idle...
> >
> > Hey everyone. First I would like to thank you all for viewing this
> thread.
> >
> > I have a 1994 Ford Mustang Cobra with the 5.0 GT-40 motor and a manual
> > transmission. It is still relativly stock however with a few small mods
> I
> > began to have a hanging idle. After installing a new TB and headers the
> > idle
> > would hang around 1800 rpms. my first thought was that i probably had a
> > leak
> > in the intake tract somewhere. So i disassembled the intake and resealed
> > everything with rtv and high-tack gasket sealer. The problem went away,
> so
> > I
> > figured I had fixed it.Low and behold, 3 days later it was raining out
> and
> > I
> > began my 17 mile trip to work. Halfway there I realized that my car was
> > still idling around 1800rpms, so the work I had done did not fix the
> > problem.
> >
> > I have since paid close attention to the conditions of the environment
> and
> > of my vehicle when the idle stays high, here is what I have figured out.
> >
> > When moving at any speed greater than 15mph with the vehicle in neutral
> or
> > with the clutch pressed, the car will idle at or around 1100 rpms, and
> > when
> > the vehicle comes to a stop it will idle at 800-900 (which is normal).
> > However, any time it is raining or very damn outside the car will idle
> at
> > 1800rpms at any speed 15mph or greater with the vehicle in neutral or
> with
> > the clutch pressed.
> >
> > If anyone has any input on why my car might be doing this or any ideas
> on
> > ways to fix this problem. please feel free to shout it out.
> >
> > Thanks
> > Keith
> > _______________________________________________
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-- 
Sincerely,
Lee M. Lemoine
KB1NQI  - Amateur Radio
http://www.turbochargedsoul.com/
'06 Subaru Legacy GT Limited - 250/250 AWD 5EAT
'93 Chevy Cavalier Z24 Convertible - 300/330 FWD 5MT (Mclaren Turbo!)