Custom EFI project

Ucu M Subrata UCU at
Sun Jun 11 12:01:23 GMT 1995

> To:             DIY_EFI at
> Date sent:      Sun, 11 Jun 95 01:23 CDT
> From:           ricrain at (Ric Rainbolt)
> Subject:        Custom EFI project
> Send reply to:  diy_efi at

> Saturn V? No, stage five.
> I will now to remove the stock igniton modules and connect them to a test
> harness which will be controlled by a PC.  I will step through all MAP and
> RPM values and record the OEM ignition advance map.  Then, I will program
> this in as my "base" map into my EFI and test my EFI using the same harness
> to verify the implementation.
> Now to install my ignition components on the engine and say "goodbye" to the
> distributors forever!
> ** MORE LATER ***
> Any questions, comments, flames or information??  Any help welcome.  I'm
> willing to share results of anything I learn from this, including choice of
> electronics and sensors.
> Ric Rainbolt
> ricrain at
Hi, nice to meet you..

I've been working on nearly the same project as you 
do.(Distibutorless Ignition with knock control and EFI (planned for 
CNG(Compressed Natural Gas)-Methane-Injected at approx 6 bar(Storage 
is 200 bar)

I use the following type of sensors:

Manifold Press(MAP) : MPX 5100 DP from Motorola (0-1500mBar)
TDC                 : UGN3140 Hall-Effect Sensor from...(I forgot)
Intake Air temp.    : LM335 Zener,precision voltage sensor (10mV/K) 
TPS                 : Ordinary Potentiometer (linear type)
Knock               : from BOSH/Audi (I forgot the type), also 
                        Accelerometer from "Metrix"(Both 

(MAP,knock sensor are hard to find here, I have to order to USA :-(   

How about the sensors you are using?
By the way, are you considering to use Knock feed-back to obtain the 
optimum Spark Advance Map for your engine?

I did data acquisition (by PC) to obtain the optimum SA Map with the 
following procedure:

1. Record the knock frequency with accelerometer + data recorder and 
play- back to Spectrum Analyzer to obtain the specific frequency 
correlated to knock. (I had 9.2 Khz for the Ford Laser 10R engine 
measured)-it has a little shift in the temperatue change.

2. Build the signal conditioning electronic circuit to process the 
knock signal from accelerometer (amp,filter,peak detector)

3. Running the engine at various RPM and Load. At each pair of RPM 
and Load I use PC to set the Spark Advance, step by step to a more 
advance SA value, and when the knock is detected(by accelerometer and 
the circuit) the PC program stop 
advancing and record the SA advance before the knock occur as the 
optimal SA(the optimal SA is right before knock occur).

4. When the SA control running accelerometer+circ still used to detect
knock (which may occur because of various engine condition)
If knock occur, it retards the timing

I used coil pack from mitsubishi (consists of 2 coil, 1 coil for 2 
spark plug)

Ok,...I'll wait for your reply ...


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