NefMoto

Is the frequency of the boost control system adjustable in ME7? If so, what is the map called?

I am not using a factory N75 valve and am using a 3 port MAC solenoid and there are benefits to running it at different frequencies. See attached table below.

On standalone systems this is an setting that can be changed.

It is adjustable in the code where the PWM output is initialized.

In my experience MAC valves are complete crap. They suffer from instability due to engine bay heat.
They used to be popular among Volvo owners (thankfully that's changing) and always caused some sort of overboost issues. Factory valves always outperformed them.

Thank you PRJ. I think that’s a bit beyond me. I honestly haven’t even grasped how to open a binary in IDA.


My experience has been the exact opposite. I’ve been using and recommending the use of three port Mac valves for many years. I’ve had them in cold and hot places with no noticeable difference in operation. Also, the factory valve isn’t capable of controlling an external waste gate utilizing both ports (top and bottom). It’s a great, inexpensive option that is readily available as well. I’ve found that they work best at a slightly lower frequency than the N75 valve though. At least in my applications.

If you remove a valve that factory calibrated boost control valve and install one thats not calibrated for the setup you will without a doubt have issues like you listed (over boost, under boost etc). I do use 3 and 4 port mac valves on vag cars without issue. 70% of all stage 2 subarus ive tuned use grimspeed / mac valves  over the crappy stock bleed valve

I guess Volvo’s factory turbo control valve is superior to VAG :)

FWIW I’ve got the MAC valve working quite well in my setup but there’s a large deadband before any boost control happens then very small increments in duty change can make a fairly large difference in boost output. I believe lowering the frequency would give the PID more resolution. I’m assuming that the factory valve is running somewhere in the 25-30htz range where I might find some benifit in running between 15-20htz.

Hardly. You missed the whole point. Nick is trying to tune his mac valve to work with his setup. Really no reason not to use the stick n75 besides hes using a "quick spool" configuration and is fine tuning it for his setup.
What you did / said is blindly changing your boost control valve without any regards to tuning the valve for the setup.

Do you change injectors without tuning? No. Same point here

I have configured only one boost valve in my life so far (in fact, I fully programmed it from scratch, including PWM configuration and interrupt handling, on two different ECU architectures) and that was a MAC valve in quick spool configuration. Never had any issues with the valve itself, or boost control, even though it had to be calibrated from ground zero up. Did not use varying frequencies either, fixed 30 Hz IIRC. One thing to look out for though, IIRC, are the Chinese clones (I did that work 5 years ago, have not checked the market since then).

I was just saying that based on personal experience and quite a few others too.
And of course I have first tried to tune it as it is supposed to be, but at some random point the behaviour changed. This was after it was tuned to. I know very well that you can’t just replace parts and expect it to work right. But as far as valves go, to each their own I guess.

My experience with MAC valves is also a strongly negative one. Give me a N75 any day of the week.
I don't understand why people fit them, I would go as far as say they are not engineered to be used for boost control, there is no restrictor etc.

There is no way to use an N75 valve in dual port operation seen in this attached diagrams.

Valve in off state needs to be closed on port 1 and allow air to pass from port 2 to port 3. When the valve is on air passes through 1 to port 2 to hold the WG shut then pulses bleeding air away from the top port of the gate.

Aren't N75s technically 3 port? The classic VAG one I had doubtful pleasure replacing on Golf TDI seemed to be so?

Yes it has three ports but, from my testing there wasn't the same flow patterns to allow it to work correctly. I don't recall as I did the testing many years ago on a different project. I'll see if I have an N75 kicking around to review what I came up with back a few years ago.

LOL this thread is hilarious

Lets hear what's comical to you.

Why because you're too dense to understand what's trying to be accomplished?

This guy is a smart ass who adds nothing but a thorn in the side. Look at his previous comments. Few words mainly mocking someone trying to learn. Guys like this will never learn and think they know everything

What software ver of CH-box are you using nick?

360101

I took a brief look through my disassembly of 360854 but ran out of play time, and my competence level is pretty borderline with such things at the moment. I can trace down ldtv, but no idea where to go from there or if I even have the right idea.

On the subject of the Mac valves in general, we dealt with dc sensitivity issues with some crappy aem standalone on the fsae car using a fitting with a very small inner diameter as a restriction. We were essentially using the turbo as a damper in that situation, but that might be helpful if changing frequency proves difficult or ineffective.

I’ve only ever used them in 4port configuration on on a tial gate with me7. Pretty good results after linearization runs, reducing gain and other tweaking. Obviously that setup is fairly different from what you have going on.

Read the datasheet for the processor, specifically about the PP, PW and so on registers that are in the PWM module.
The N75 DC gets generated by the primary processor (not the IO extender). The C167 has 4 PWM outputs in the PWM module.
Frequency is configurable and it is set up in an init block, all you have to do is change a single constant. You need to find which output is used for the N75 though (as it differs depending on ECU family), but it's pretty straightforward.

So I've done some digging and found a little bit of info that I think should be helpful. It would be more helpful if I knew anything about dis-assembly but I am willing to learn.

I found the datasheet for the 167 and have found the addresses for PWM outputs 0-3.

I then searched for those addresses in IDA and came up with the following.

It may be borderline spoon-feeding but am I headed in the right direction? Where should I go next?

Load the binary to correct address (0x800000), convert it to code, then check references to PW registers.
Won't really make it any clearer, as you'll have to check actual functions working with those. That's a bit too difficult for someone with no (dis)assembly background.