problems with EFI car idle and pressure sensors

[Matt Beaubien]

I would argue that if you move the throttle enough to
change the airflow, the MAP value would change as a
result.  The engine responds to manifold conditions,
so that's really what's controlling the engine.

Put one way: if the TPS change is small enough that
MAP isn't affected, would the engine run different?  I
would say no.

Put another way:  if you had a turbo engine where MAP
and TPS aren't "directly connected" (e.g. turbo lag),
would you rather fuel based on TPS or MAP...?

My two bits.

Matt.

--- Bruce <nacelp at bright.net> wrote:
> 
> MAP will lag TPS.
> Depends on what kind of response you want, and
> intake tract ducting.
> Bruce
> 
> 
> 
> From: "Matt Beaubien" <mrbeau0 at yahoo.com>
> Subject: Re: problems with EFI car idle and pressure
> sensors
> > Why is TPS AE a must have?  Kinda redundant if you
> have a good MAP signal
> > and proper calibration.
> > Matt.
> 
> > From: "Bruce" nacelp at bright.net
> > Subject: Re: problems with EFI car idle and
> pressure sensors
> > > Don't you mean add a MAP to it?.
> > > Ditching the TPS, would leave you with RPM n
> MAP.
> > > TPS AE is kind of a must have
> > > Bruce
> 
> > > From: Tony Bryant
> > > Subject: Re: problems with EFI car idle and
> pressure sensors
> > > TPS & RPM systems are TOUCHY. The trouble is
> that at low RPM, the
> > slightest
> > > hint of a throttle
> > > opening needs to cause a big change in injector
> pulse length.
> > > Ditch the TPS, and run a MAP sensor instead.
> Grab a MAP sensor from a
> 80's
> > > 4AGE toyota corolla,
> > > three wires: 5V, Gnd, and output (0-5V -  4V ~=~
> 101.3 KPa).
> > > TPS/RPM is not for beginners. Or anyone who
> cares about idle.
> > >
> > > From: David Sackett
> > > Subject: problems with EFI car idle and pressure
> sensors
> > > hi, i'm developing a simple EFI computer based
> on a Atmel AVR
> > > microcontroller running at 8Mhz for a Uni
> project. I have installed it
> on
> > my
> > > old 1977 Saab 99 and merged it with a Bosch
> D-Jetronics fuel injection
> > > system. the car originally had carbies and i
> have only used the inlet
> > > manifold, injectors and fuel system from the
> bosch system.
> > >
> > > just to get started I decided to only use
> throttle position and rpm as
> > > inputs to the computer. a lookup table is used
> to determine the correct
> > > injector open time from these two inputs. we
> have successfully performed
> > > test runs in the car and it accellerates fairly
> well.
> > >
> > > the problem we are having is that we cannot get
> the car to idle
> smoothly.
> > > the car refuses to run on all cylinders until it
> is above about 2000rpm.
> > the
> > > car runs VERY rich and the plugs have to be
> cleaned every 1/2 hour or so
> > of
> > > running. if we reduce the mixture at idle it
> just stalls. also the
> system
> > > fires all injectors at once every revolution of
> the crankshaft. i have
> > > replaced much of the ignition system and am
> fairly sure it is working
> > > correctly.
> > >
> > > does anyone have any ideas as to how to fix the
> idle?
> > >
> > > also i've read about the Megasquirt system that
> uses an MPX4100 MAP
> > sensor,
> > > and as a general improvement to my system i wish
> to add a similar
> circuit
> > > board mounted sensor. I live in Melbourne
> Australia and cannot find any
> > > distributors who will sell me less than 20 with
> a lead time of 12 weeks.
> > > does anyone know where i may be able to get just
> one sensor or if there
> > are
> > > any other suitable alternatives?
> > >
> > > thanks
> > >
> > > David
> 
> 
>
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