problems with EFI car idle and pressure sensors

[Bruce]

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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