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Author Topic: How does the n75 work with tuning?  (Read 4810 times)
tadope
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« on: April 01, 2021, 10:12:44 AM »

I have two n75 valves. Im not sire which to use.
They both provide slightly different boost patterns.
My original valve is older, and had the screw played with some.
It gives more boost early on, but is more rough.
I also have a fresh new valve that runs very smooth but makes little boost down low, and more peak boost.

I was going to get a tune file from user “marty”

Im wondering which valve to go with.

Will the tune even care which n75.  Or does the new tuning overwrite then75 effects anyways?

2001 tt 225 amu
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Blazius
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« Reply #1 on: April 01, 2021, 12:21:39 PM »

The hardware difference usually requires software tuning, the tuner will tune for the hardware you have, just dont go screwing around with it afterwoods.

Different revisions have different springs/ coils, orificies etc so its impossible to know, since there is no generalised table for this(yet, would be nice).
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nyet
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« Reply #2 on: April 01, 2021, 06:47:00 PM »

stop fucking around with fucked up n75s that some dipshit thought they could fix.

get a stock one, start with that.
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tadope
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« Reply #3 on: April 02, 2021, 10:31:05 AM »

Ok. I'll go with the new one
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tadope
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« Reply #4 on: April 09, 2021, 11:03:14 AM »

The hardware difference usually requires software tuning, the tuner will tune for the hardware you have, just dont go screwing around with it afterwoods.

Different revisions have different springs/ coils, orificies etc so its impossible to know, since there is no generalised table for this(yet, would be nice).

So does this mean that the software somehow knows the difference in n75 valve?
How can the software know that there is a mechanical change (valve)?

I'm a noob so correct me if I'm wrong but I thought it goes like this:
Software does " requested boost"  , mechanical n75 talks to wastewater, then you get "actual boost"
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tadope
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« Reply #5 on: April 09, 2021, 11:04:55 AM »

stop fucking around with fucked up n75s that some dipshit thought they could fix.

get a stock one, start with that.

Ok so the issue is that vw put the same n75 part # on all 1.8ts.  But they all have different settings for the screw in them!!!!
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nyet
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« Reply #6 on: April 09, 2021, 04:42:09 PM »

So does this mean that the software somehow knows the difference in n75 valve?
How can the software know that there is a mechanical change (valve)?
There are maps that govern assumptions on how the N75 behaves

Quote
I'm a noob so correct me if I'm wrong but I thought it goes like this:
Software does " requested boost"  , mechanical n75 talks to wastewater, then you get "actual boost"

No. Not even close.

A better analogy is a thermostat. How does your heater know how to get to a certain temperature?
« Last Edit: April 09, 2021, 04:43:41 PM by nyet » Logged

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tadope
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« Reply #7 on: April 10, 2021, 06:23:19 AM »

There are maps that govern assumptions on how the N75 behaves

No. Not even close.

A better analogy is a thermostat. How does your heater know how to get to a certain temperature?

Ok.  Thanks for clearing that up

Let me update my question then.   
Can I just tell my tuner how to make my boost curve? Or does the n75 determine that?   Got a new uroparts n75 and it boosts good up top. But lousy down low.   The old oem one boosts good down low but lousy up top!!
I can try a new oem but they r $$$$.

If the tune will end up overwriting those n75 changes then I probably have nothing to worry about??
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nyet
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« Reply #8 on: April 10, 2021, 02:39:28 PM »

Can I just tell my tuner how to make my boost curve?

They should determine it, not you, based on the compressor map of the turbo you intend to use

Quote
Or does the n75 determine that?

No. The brand of thermostat you use does not determine the temperature of your house.

Quote
Got a new uroparts n75 and it boosts good up top. But lousy down low.   The old oem one boosts good down low but lousy up top!!
I can try a new oem but they r $$$$.

If the tune will end up overwriting those n75 changes then I probably have nothing to worry about??

There is nothing in either of those two paragraphs that makes any sense.

Get a functioning n75, one that has not been fiddled with by a windowlicking moron or sold as an "upgrade" by a fucking scammer.

Then the ECU needs to be tuned properly for that N75 to make the boost that the ECU requests.

There are two different functions in the ECU

1) determining target boost (this is has nothing to do with what N75 you are using)
2) controlling the n75 to achieve that goal (this depends on the target boost and the kind of n75 you are using)
« Last Edit: April 10, 2021, 02:42:10 PM by nyet » Logged

ME7.1 tuning guide
ECUx Plot
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Trim heatmap tool

Please do not ask me for tunes. I'm here to help people make their own.

Do not PM me technical questions! Please, ask all questions on the forums! Doing so will ensure the next person with the same issue gets the opportunity to learn from your ex
tadope
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« Reply #9 on: April 10, 2021, 05:54:31 PM »

Ok thanks. Sorry my paragraph was hard to understand.
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