TBI

[Bruce Plecan]

-----Original Message-----
From: Martin Powlette <marquise at candw.lc>
To: diy_efi at efi332.eng.ohio-state.edu <diy_efi at efi332.eng.ohio-state.edu>
Date: Monday, August 24, 1998 8:25 PM
Subject: Re: TBI


How did this thing not set any codes?.
As I understood things it was hard to start before some work was done on it.


Well, there is a clear flood mode, that can operate one of several ways.
Both were mentioned just recently but as I recall one was a no injector
spray, and another very lean (22:1).
Cheers
Bruce
>I was hoping to get more discusion on the subject but anyways here is an
>update.  I tried Bruce"s test for the IAV and it did not move in or out
when in
>diagnostic mode ign. on and or off. Fuel pressure ,relay and fuse is ok  I
also
>noticed that when cranking there was no fuel at the injector.  Almost like
the
>ECU didn't know the engine was trying to start.   I back probed the TPS and
>noticed that the same 5V in was going right back out throttle in idle
position
>or otherwise, as if it kept on reading full throttle. Toyota has a default
>fuction that stops the fuel pump from pumping in wide open throttle when
>cranking it also prevents flooding when cranking.   I disconected the TPS
and
>the hard start was gone, instant fuel at the injector.  I guess the ECU was
>substituting the TPS signal.  I will replace the TPS but can someone tell
me
>what is the exact rtelationship between cranking and TPS reading or have I
got
>it figured out already.  Thanks for the reply Bruce.
>
>Martin Powlette wrote:
>
>> I saw a mod to the TBI injector on a web page it is a capacitor in
paralell
>> 0.1 mfd 250V.
>> What does it do or solve???
>> Someone said the fuel pump relay may be bad and the pump is being driven
off
>> the oil pressure circuit as a default backup !!!! comment
>> Martin
>>
>> Bruce Plecan wrote:
>>
>> > -----Original Message-----
>> > From: Martin Powlette <marquise at candw.lc>
>> > To: diy_efi at efi332.eng.ohio-state.edu
<diy_efi at efi332.eng.ohio-state.edu>
>> > Date: Sunday, August 23, 1998 9:06 PM
>> > Subject: TBI
>> >
>> > >I have seen qite a bit of talk on Gm vehicles so I am confident a few
of
>> > >you guys are familar.  GM TBI V8 5.7 lit I recently did an intake job
on
>> > >one of those engines and even prior to and now it has a hard start.
>> >
>> > Freguently, fuel pump starting to go.
>> >
>> >  The
>> > >ignition timing is set at O deg. tdc as the specs recomends but still.
>> > >I pulled out the IACV(idle air controll valve ) and though the book
says
>> > >to wiggle and apply firm pressure to push the pintle the thing is a
>> > >bitch just how much is firm pressure????
>> >
>> > It's a stepper motor, better off to buy a stepper motor controller if
>> > you wan to play with it.  ($25ish).   Easy to ruin with too much force.
>> >
>> >  when I finally got it down I
>> > >tried to exercise it back out , my fingers got soar after almost 10
min
>> > >of side to side and pull.   Has anyone had that experience.  I
connected
>> > >the unit whiles out and grounded it on the throttle body, turned the
>> > >ignition on and the thing does not buldge, just a slight twitch but no
>> > >significant movement whether it was all the way in or out.  Please
>> > >advise.  I know the posting is late but I want to get on it tomorrow
so
>> > >if anyone is out there please help.  Sorrry about the subject matter.
>> >
>> > Short pins A-B at ALDL and that will extend the IAC.
>> > When you trun the key off will retract.
>> > Must drive over 40 MPH for IAC to reset, after any of this.
>> > >
>> > >Martin
>> > >
>> > >
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