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Noise from PWM idle valve
Posted: Mon Nov 09, 2009 4:47 am
by Ferd
DIY PNP Megasquirt, MicroSquirt BG 2.890 code.
Hi
The problem I have is noise (I think) from my PWM idle valve (2 wires)
With the ignition switched on the Tps and coolant temp gauges on megatune jump around with air idle plugged in. As soon as I disconnect it they stop.
I have the flyback diode in place and have even replaced it and tried another at the idle plug with no joy.
Any ideas Ferd
Re: Noise from PWM idle valve
Posted: Mon Nov 09, 2009 7:41 am
by Matt Cramer
What sort of PWM IAC valve is this, and what frequency are you trying to run it at?
Re: Noise from PWM idle valve
Posted: Mon Nov 09, 2009 9:35 am
by Ferd
Hi
It’s a Ford iac valve as used on the Zetec and its set at 80Hz in the idle control.
I was having trouble getting the car to idle and tried adjusting it but this did not work.
I found out it was the 10 steps of the PWM idle dutycycle my car will not idle at 100 but is ok at 80.
Could I have damaged the Pwm transistor?
Ferd
Re: Noise from PWM idle valve
Posted: Mon Nov 09, 2009 11:38 am
by Matt Cramer
Most Ford valves we've seen run at more like 300 Hz. I think 320 is the closest value you're allowed to enter.
Re: Noise from PWM idle valve
Posted: Tue Nov 10, 2009 6:15 am
by Ferd
Hi
Tried setting the idle control frequency to 320Hz and it’s still the same and I also tried another IAC and it’s still the same.
Can I just clarify the PWM idle connection on the DIY PNP with you to make sure I have them right?
I have the flyback diode in R5 one leg in the left hole and the right leg in the 5v hole. Is this right or dose it go in the 12v next to it?
I have the output for the idle in the IAC hole just under the proto area next to Tech-out.
Other than that I am at a bit of a loss.
Ferd
Re: Noise from PWM idle valve
Posted: Tue Nov 10, 2009 6:18 am
by Matt Cramer
You should have the banded end going to 12 volts, not 5 volts. You'll probably have electrical noise issues if you wire it to 5 volts, at the very least.
Re: Noise from PWM idle valve
Posted: Tue Nov 10, 2009 8:09 am
by Ferd
Hi Matt
I have just changed the diode and put it in the 12v hole as I did have it in the wrong hole.
I may have had a 1k resistor in R3 wrong as well as I am using the Edits unit.
Any way it’s really good news as after I generate an idle dutycycle curve 0 to 80 she started and runs really well and idles and the gauges have stopped moving.
Matt you’re a star thank you ever much for your help I am sure I will be back.
Ferd