hello i got an interesting project but have no experience in designing a circuit
so basic story is that i got an old volvo that get too much fuel with the new generation fuel, i think its bechause new fuel contanes more oxygen burn cleaner and leave more oxygen in the exhaust witch the O2 sensor pick up and the ECU think its running lean then compensate with more fuel.
anyway how to solve this?
i bought ostrich 2.0
and did the steps in this forum:http://forums.turbobricks.com/showthread.php?t=227153
it turns out that the ECU stay at what is thinks is AFR 14.7 that is 1 volt from the LAMBDA (O2 sensor) no matter what is done in the main fuelmap
so now i can change the fuelmap and the ECU know what to do but get answer from the O2 sensor that say its all wrong!
an O2 enhancer can be used to fix this but then it will change the same value no matter load at the engine, and the engine need more fuel at a higher load to prevent pinging and self destruction.
so my question here:
Can anyone help me to design an citcuit that is controlled by PWM?
Enhancer circuit: http://hydrogengarage.com/DIY/DIYinstructions.html
http://hydrogengarage.com/DIY/O2_sensor_schematic.jpg
this Schematic need to be controlled by PWM and i got only 1 O2 sensor so i only need one side of this circuit
Circuit needs:
-run from car voltage 9 - 17v
-Enhancer for 1 O2 sensor
-to be controlled by PWM
-pot to adjust enhancer value at max dutycycle
-pot to adjust enhancer value at min dutycycle
-linear enhanser value between max and min dutycycle
-pot to adjust dutycycle input bechause my measurements may not be corect
-bechause the ECU vant to keep AFR to 14,7 the voltage from O2 sensor is 1v
so the enhancer need to add or subtract in milivolts, how much volt totaly i dont know
but it could be understood from the chematic of the enhancer
wiring diagram of ECU and other stuff:http://ipdown.net/jetronic.info/tiki-in … 20Diagrams
load signal is found on #8 on ezk(ignition) and #25 (LH2.4)
here is EZK
http://ipdown.net/jetronic.info/tiki-do … 64&display
My measurements:
signal peak to peak with reference voltage at ground: 1,406v
time with at idle: 90 us
time with at trottle (may not be full load): 416us
square wawe PWM 2,404KHZ (this is a bit unstable but around 2,4KHZ
dutycycle can be calculated some how from time with at trottle and 2,4KHZ same with idle
the reason odd measorements is i got only a old ocilyscope and i have no training using it hehe
i got a smal video and picture from measureing but dont know how to add it here
hopefully someone can help