problems with EFI car idle and pressure sensors

[Matt Beaubien]

Why is TPS AE a must have?  Kinda redundant if you have a good MAP signal
and proper calibration.

Matt.

----- Original Message -----
From: "Bruce" <nacelp at bright.net>
To: <diy_efi at diy-efi.org>
Sent: Tuesday, September 19, 2000 9:40 PM
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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