Increasing Boost - the best way to handle TP

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htczenit
Posts: 6
Joined: Thu Sep 05, 2019 11:58 pm

Increasing Boost - the best way to handle TP

Post by htczenit » Wed Sep 11, 2019 2:25 am

Hey there,

quick introduction, I am a rookie when it comes down to engine management.
I spent the last year reading and researching everything engine management related. I just want to get
the knowhow to "manage my engine". Not because I am looking to make money of it and become a professional,
but because I have the urge to know how things work and I hate paying people to do things that I would love to be able to do myself.

Enough chitchat, lets talk business :)

After all theory I finally took the step and started with my car.
Quick setup overview:

Nissan 200sx S14a EDM with Feature Pack Nistune
Greddy FMIC
3'' Exhaust Catback
200ccpi cat
740cc Nismo Injectors
OEM MAF

My goal:
- get the 740cc Nismos to work correctly
- increase Boost on OEM Turbo to 1.1 Bar (16 PSI)
- learn in the process

What happened so far:
I fitted the 740cc Nismo and replaced my stock (370cc) injectors.
I thought about fitting a PMAS HPX Maf (actually it is fitted but not connected), but opted to stay the OEM MAF for now. The reason is pretty simple:
I did a few logs when running up to 0.85 Bar of Boost with everything OEM, and I saw that MAF Voltage was not exceeding 4,4 V , which reads about 60% of the max capacity.
A quick research showed that several other people maxed out the OEM turbo while using the OEM MAF.
Long story short, to save me the fiddling with K and a PMAS Sensor, I decided to keep the OEM (expecting to be more forgiving to novice like me).

I set TIM to 50% of the original value (512 -> 256) and simply adjust the fuel map by -50%.
Then I took of and adjusted the short fuel trims to a tolerance of 5%.

Car drives like a beauty on low loads, transitioning to boost is better then I expected it to be for know.
A few tweaks to the fuel map, mainly increasing fuel setup a rough AFR ratio for now.

So I did a quick and easy boost run (while monitoring knock) with desired target boost of 1.1 bar.

The problem / question

As expected the original TP scale would not be sufficient. It currently is scaled up to 112, which I already hit when I was just running 0.85 bar.
Yesterdays log showed 121 TP @ ~4000RPM and 1.1 Bar of boost.
So I basically blow through the table like a king :D

Of course I have tried to read up as much as possible about this topic, and as mentioned I was totally aware it to happen, but I do not seem to find the proper 2019 way of handling this issue.

As far as I can see there are a couple of ways to approach this issue:

- Rescale TP up top:
e.g. rescale the range of 70,78,96,104,112 to 70,85,100,115,130 (just an example)

This however, would IMHO destroy the resolution up top whilst keeping it down low.
I don't want to do this, as I would loose "control" in the area it matters most (IMHO).

- Rescale TP down low:
e.g. rescael 16,24,32,40,48,56 -> 16,30,45,60

This would give some room in the high loads, whilst sacrificing a bit of room down low.
This would be a solution I could live with, IF you guys could confirm it would not highly affect factory TP scales

- Change K:
This is a thing I can't seem to wrap my head around.
Normally K would be adjusted when changing MAF to something different.
It would affect the whole TP range and map, but you would stay inside the factory TP range.

As far as I can tell, changing K would be the way to go.
But to be honest, research on this topic showed different approaches, and they all seem to make sense to a degree.

When changing K, wouldn't this directly effect paramets like VTC engagement (afaik set to 27 TP), as 27 TP wouldn't be at the same load as it used to be?

So which way do I go from here?
Change K, rescale lower section or rescale upper section of the maps?


Thanks in advance,
I'm looking forward to discuss the different options with you :)

BR from Germany,

Mike

unex
Posts: 80
Joined: Sat Aug 06, 2011 6:59 am

Re: Increasing Boost - the best way to handle TP

Post by unex » Wed Sep 11, 2019 8:04 am

in short:
rescale K so that at max boost you hit somewhere 100-120. Rescale fuel and ign maps to get more resolution on high load, and lower resoliution on low load, because oem have too much resolution on low load, and vice versa.
p.s. fit 350z maf, boost 1-1.2, later change turbo to something like gtx2971. Thank me later

htczenit
Posts: 6
Joined: Thu Sep 05, 2019 11:58 pm

Re: Increasing Boost - the best way to handle TP

Post by htczenit » Wed Sep 11, 2019 7:58 pm

Ok, so I'll try rescaling K.

Is it possible to somehow calculate this?
For example I reached TP 125, which is 10% higher then stock, could I simply lower K by 10%, raise TIM by 10% and be were I am at right now?

I am not sure, as the VQ value is not linear.

Or is adjusting K a rather dark walk, doing it step by step?

htczenit
Posts: 6
Joined: Thu Sep 05, 2019 11:58 pm

Re: Increasing Boost - the best way to handle TP

Post by htczenit » Thu Sep 12, 2019 10:28 pm

So last night I went out to proceed with my tune.

I roughly estimated how much I will overshoot TP, then lowered K by 16% und increased TIM by 16%.

A couple of tweaks to TIM quickly got my trims to less then 5%.
Car drives good.

I tackled the fuel map by given it some more, and achieved a rough fuel map.

But then timing gave me a headache.

In the lower right corner of the ignition map there are values highlighted.
What to they express? At first I thought it was VTC, but the highlighting checkbox for VTC quickly showed me that was not the case.

The thing is, if I go WOT in 5th gear, starting from roughly 2500, as soon as boosts builds, at roughly 70-80 TP it will use timing values of up to 60, immediately causing detonation :shock:

So far I can't figure out why. Any clues?

edit:

In the meanwhile, I discovered those values to be Knock Flags. This does not explain to me why ign would scramble so much, but at least I know why they are highlighted.

How exactly do they work?

edit 2:

I just spend some time to look over the logs and the maps. I saw that while pulling IGN in raw view, I dropped below 0 in a couple of cells, which might have caused the IGN spiking.
I'll test this tommorow :)

my1path
Posts: 52
Joined: Fri Apr 06, 2012 8:06 am
Location: Southern CA, USA

Re: Increasing Boost - the best way to handle TP

Post by my1path » Sat Sep 14, 2019 7:43 am

Just a quick note on TP sacles, there is a pretty good write up in here about scaling and how to make it most functional.
But in a nutshell what I have done is gentle idle to redline pull while running a trace and watching a vac gauge and not let it dip below 13-15 HG. This is your light load zone. For me trace showed 18-36 TP in the low RPM range so resolution beteen 18-30 TP really doesn't matter, so make it just two or thee coulmns: one far left for engine braking and one or two for light load driving. This frees up 13 or 14 coulmns above 30-36 TP for whatver resolution you can work with.

Matt
Site Admin
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Location: Adelaide, Australia
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Re: Increasing Boost - the best way to handle TP

Post by Matt » Tue Sep 17, 2019 9:50 am

Need a copy of the tune/log or at least an image of your timing map

Recent updates in the last versions were added to show the knock enabled region (right click to toggle on/off) as well as the knock flags within that region (documented)

Timing is awfully high on the consult reporting side of things. Compare your ignition timing map against a factory tune file

htczenit
Posts: 6
Joined: Thu Sep 05, 2019 11:58 pm

Re: Increasing Boost - the best way to handle TP

Post by htczenit » Thu Sep 19, 2019 6:22 am

Thanks for the replies guys :)

Let me get you some files, see attached:

mbusch_sr20det_s14a_original_062019_backup.bin
This was the base image on my ECU.

mbusch_sr20det_s14a_inj_resize_working_copy_ign_test.bin
This is the currently burned file. The problem with the ignition was corrected and didn't occure again.
As far as I can tell, this should be pretty conservative.
Only adjusted Fueling so far to reach desired A/F in all boost levels. (max. 1.1 Bar)

mbusch_sr20det_s14a_inj_resize_working_copy_tp_rescale.bin
This is an experimental, not yet tested image, were I tried to rescale TP.
Currently I reach up to ~110 TP, so I gave a little more room up top as I haven't been able yet to log whole 4th gear.
Timing is awfully high on the consult reporting side of things.
What is this suppose to mean? I checked the actual timing vs. consult reading, and it was the same :|
Attachments
mbusch_sr20det_s14a_original_062019_backup.bin
(64 KiB) Not downloaded yet
mbusch_sr20det_s14a_inj_resize_working_copy_tp_rescale.bin
(64 KiB) Not downloaded yet
mbusch_sr20det_s14a_inj_resize_working_copy_ign_test.bin
(64 KiB) Not downloaded yet

htczenit
Posts: 6
Joined: Thu Sep 05, 2019 11:58 pm

Re: Increasing Boost - the best way to handle TP

Post by htczenit » Thu Sep 19, 2019 6:24 am

Furthermore here are the corresponding Log Files:

Nistune_2019-09-14_2322_05_VOLL_11bar.csv
This one is the latest file I took with 1.1 Bar Full Boost in 3rd Gear.

Nistune_2019-09-11_2307_38_VTC_HIGH.csv
This file has the issue with the very high ign levels. You can clearly see them spiking HIGH.

Thanks for help guys :)
Attachments
Nistune_2019-09-14_2322_05_VOLL_11bar.csv
(242.51 KiB) Not downloaded yet
Nistune_2019-09-11_2307_38_VTC_HIGH.csv
(33.84 KiB) Not downloaded yet

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