PWM IAC

[rg2200]

I have a Ford 5.0L V8 (in a Mazda B2200 pickup) with a MS-II 3.0 w/relay board using Megatune 2.25 and no MSExtra. I can't seem to get the Ford PWM IAC to work. I've tried 2 different IAC's and I just don't seem to get a response. I have the fidle relay jumpered on the relay board. if I unplug the connector to the IAC, with power on, but engine not running, I get 12V to one wire going to the IAC, and get continuity from the other wire to the fidle wire on the relay board. I've set it to PWM Warmup in megatune, with the PWM Frequency set to 320Hz, and Start value at 160 (I've tried varying start values - and power cycled between changes.) but I still get nothing. I must have missed something? I haven't recently double-checked the MS-II, but had double-checked months ago when I had tried to get this working before - TIP120 to Q4, no Q20, no D8, jumper R39, plus I have a 1N4001 across the 12V and fidle (I originally didn't have this diode, but the behaviour didn't change after adding it.)

Are the Ford PWM IAC's sensitive to the wiring polarity? (Do I maybe have the 12V and fidle wires backwards on the IAC?)

Any ideas?

Thanks.

[Matt Cramer]

Some of the Ford IACs have a built in bypass diode and can't be wired backwards.

Also, could you post a copy of your MSQ?

[rg2200]

Matt,

Here's my MSQ. Do you think it would hurt to try the wiring to the IAC the other way around?

[Matt Cramer]

Your MSQ appears to call for pinning it open full time - Ford valves close at zero duty cycle.

[rg2200]

Matt, Thanks. Where do I change the duty cycle settings for the IAC - is it in the Idle Control dialog in Megatune, or elsewhere? Sorry for the newbie sounding question.

[rg2200]

Matt, don't worry about it, I found the PWM Idle Duty Cycle settings, after testing TunerStudio and finding it in there (easily). I now have working PWM IAC. Of all the documentation I've read (megamanual numerous times), I don't seem to recall anywhere any mention of going to the PWM Idly Duty Cycle form and putting the settings in there. It makes perfect sense, but when you're new to this, not everything is so obvious, and if it's not in the 'instructions', then you don't want to mess with it.

On a side note - do you prefer TunerStudio or Megatune? I'd never tried TunerStudio before, but doing more research, most people seemed to be using TunerStudio.

Thanks again, as always, for your prompt attention.

[Matt Cramer]

We use TunerStudio almost exclusively. Much easier than MegaTune, and some of the newer code versions don't work with MegaTune.

[rg2200]

Matt,

Thanks. I would certainly agree that TunerStudio is easier to use - I managed to figure out the duty cycle settings almost right away with it and completely missed them in MegaTune. I was concerned that it used a different (incompatible) format of MSQ from megatune, but I was able to open the MSQ created from Megatune no problem in TunerStudio - it's going to be the tool I use from now on.

My next issue is EGO (my Innovate O2 Gauge appears to read correctly, but Megatune/TunerStudio always show a very low number like 9-10 when the gauge is reading 12, for example, and the megatune reading never seems to go above about 10.5) I'm going to do some research and try to open-air recalibrate the O2 sensor again etc. It had been working, then at some point just started reading wrong. I'll double-check the grounds and wiring etc., but you'd think that the if gauge reads ok, then the wiring would likely be ok, and then it's just settings/configuration in TunerStudio/Megatune.

Anyway, thanks again for the great support.

[Matt Cramer]

Make sure you've set the MS2's look up table up for it under Tools -> Calibrate AFR Table.

[rg2200]

Matt,

Thanks. In the Calibrate AFR table, I'd tried several WBO2 models listed (besides the innovate LC-1) to see if I would get the correct readout and all had similar problems - the LC-1 seemed the 'closest'. I'll check the wiring and grounds, and try recalibrating it as well and see where I get with it.

[rg2200]

Matt,

I removed the O2 and calibrated it using the pushbutton method, then, for good measure, plugged it into the laptop and recalibrated it using the LM Programmer. The AFR ratio was set to 'custom' for some reason, so I reset it to Gasoline/14.7. I also, of course, put the terminator in the Input on the LC-1 (it wasn't in place, I thought it was only needed for programming, but I've left in plugged in). Then, certainly the most important part, I looked at the outputs and realized (even though I'm pretty sure it's well documented) that the yellow wire from the LC-1 is narrowband and the Brown is Wideband - I had the XD-16 gauge feeding off the brown wire, and had the yellow going to the MS-II. This project has been ongoing for 2 years, with a good 9 months of not touching it at all, so I'm not sure why I hooked it up like that originally, but it's been so long know that I'll never remember why - odd thing is that I'm pretty sure that I had valid readings at the start... Anyway, needless to say, after doing the above and tapping into the brown wire for the MS-II, I'm now getting good readings in both TunerStudio and on the XD-16 Gauge. I'm assuming that there's no issue with feeding the same output to both the XD-16 and the MS, since it's just outputting 0-5V?

I chalk it up to another newbie mistake - hopefully others reading this who are new to MS will not make the same mistake after reading this.