Ford PWM idle air control testing on bench.

PJF · Post by **PJF** » Tue Jun 13, 2006 6:30 am

Hello all-

I have MS-II, V3 main board, Megatune 2.25, and 2.35 embedded code, all hooked up to a relay board.

I bought the PWM kit from DIYAutotune which included a new Q4 and R19. I jumpered the relay as per the megamanual. Everything seems okay. When I power up the MS I get a a good ground on the FIDLE attachment point on the relay board.

In Megatune I set my Idle Control to PWM Warmup, burned it to ECU and rebooted.

Here is my question. Should anything happen with the PWM valve hooked up? I get a solid 12 volts on the multimeter with the FIDLE open. When I jumper one side of the IAC valve to hot and the other to FIDLE the voltage drops to 6 volts and the valve does nothing, same thing if I reverse the leads, I can blow just as much air through it as when it is unhooked. I have set the start value in a bunch of places and it is always the same.

Amd I doing something wrong? Does the PWM valve need other engine inputs such as RPM before it will start moving? I am pulling my hair out on this. I searched but couldn't really find anything.

Thanks in advance for any help.

EstateAgent · Post by **EstateAgent** » Tue Jun 13, 2006 7:39 am

I dont think you can test these on the bench as they need to be pressurised closed (when the engine is running, they naturally get sucked closed then the ECU opens it.).

Perhaps a vacuum cleaner could provide the vacuum needed?

I know what you mean with the Ford valve though. All info I find is basicly 'bash numbers 'til you get it'

I will be some real-life numbers by scoping the Ford ECU when I get time and getting the MS to mimmick that.

PJF · Post by **PJF** » Tue Jun 13, 2006 7:59 am

Ahhhh, thanks for the insight estate agent! I didn't realize they needed vacuum to operate properly.

But more importantly I am a victim of not reading directions closely enough. The megamanual clearly states that PWM sensors must be set under the PWM dutycycle menu and NOT the Idle Control menu.

When I went to the PWM dutycyle menu I saw that the setting were calibrated up to 160 degrees F. With no coolant sensor hooked up here on the bench megatune is reading 170 degrees! Outside the parameters or what megasquirt considers "warmup." Hence there would be no movement of the IAC. As I have ground at FIDLE I am guessing things are working properly. Time will tell when I finally fire the engine.

I struggled with this for hours last night and broke down this morning and posted my question. Then answered it myself!

Thanks for the response though. At least I learned something out of this.

EstateAgent · Post by **EstateAgent** » Tue Jun 13, 2006 9:29 am

PJF wrote:But more importantly I am a victim of not reading directions closely enough. The megamanual clearly states that PWM sensors must be set under the PWM dutycycle menu and NOT the Idle Control menu.

Trivial:
I guess the MS-II is different there then for the menus?
I'm using MSnS-E and the PWM menu is only found by clicking 'Idle Control' under 'More Settings'

MegaScott · Post by **MegaScott** » Tue Jun 13, 2006 3:30 pm

When I test my Megasquirts when hooked up to my little test bench i made up, complete with a Ford EEC connector and all the sensors, I can vary the coolant temperature and the PWM duty cycle changes, I experiment with a Potentiometer and set it so the valve has the most range of operation, you can see the valve moving inside the housing, you must have the solenoid bolted to the valve housing. You must also at least have Idle RPM going into the Megasquirt.