NefMoto

Hello guys

I'm working on my own car (MED9 EA113 CDL) and i've fitted Porsche DFI injectors which reference is given in forum.

According to the FR, latest EOI is limited by software, but there is enough room for playing with SOI and stop the injection later or sooner before the firing stroke.
For now, and before working on the "tune part" i'm concerned about EOI & SOI for idle & cruising.

Already done some researches (FR, Google, etc) and i can't find any information regarding the best EOI for GDI engines.
With the best one, torque, fuel consumption and emissions will be improoved.
So let's say the stock software is providing the best EOI available with stock injectors (in order to have the lowest fuel consumption & emissions), is it a good idea to try reaching the same EOI with upgraded injectors ?

I'm running E85 fuel, and i guess good EOI for petrols is maybe not the best for E85 .. am i right ?

IMO it is not so easy, like you imagine it. ;)

In every point you need separate parameters. For example: if you change the SOI @ low rpm it could maybe have negative effects of mean pressure, the temp, exhaust gas component, exhaust gas pressure, exhaust gas emission, lose of torque, neg gas-exchange cycle ............................................................................

Take a look @ AWEA group. ;)

There are many departments in VAG group, they work together to improve the process and find the optimum.

You can try to get parameters from a file that fit to these injektors, otherwise i woundn`t touch it.

BR

Yeah so they have done the job in order to get the best EOI, so maybe trying to reach same EOI with upgraded injectors is a good solution, when you run same fuel as stock i guess
But i run E85

Maybe i can have a look in Simos 12/18 what is done in nativ flex fuel  ::)


The problem is if i leave them stock, my idle rpm is not fine. I'll try to lower SOI & rail pressure as a first try then report  :)


Of course i did, and i didn't got answers haha

Your first step is to learn that GDI and TDI are two different things.
On Diesel the injection point is also the ignition point, this is not the case on a GDI engine.
After you have understood that the fuel is not ignited before there is a spark, you can start doing something...

Changing the injection angle does not magically change torque on GDI or fuel consumption.
Especially in non-knock limited area it is almost irrelevant, as long as you don't spray way too early.
This is also why if you look at the actual "target" SOI maps they are almost flat with a single value, with a little change on higher RPM.
It simply does not matter all that much.

The limitation is "abbruchwinkel" or the latest possible EOI. This is the point where the pressure in the combustion chamber is getting close to the rail pressure, so no more meaningful amount of fuel can be injected/atomized. Obviously if you increase the rail pressure, this moment arrives later and because almost no one understands this, people tend to fit bigger injectors, when in many cases a bump in the rail pressure is enough to not only increase the maximum flow through the current injector, but also extend the injection window.
Limitation maps: KLWESABR/KFWESABRGM

For SOI the main limitation is the point at which the exhaust valve is closed. If you start spraying before that, you are spraying into the exhaust.
The second limitation is the volatile nature of gasoline. If you spray too early, the fuel gets deposited on the piston, it also gets heated a lot more and knock occurs.
Limitation map: KFWBHO1SMX.

So the tuning window is tiny. In fact, stopping spraying somewhere close to the "abbruchwinkel" is usually always a safe bet. You will not be able to ascertain whether you get a bit better atomization by spraying a bit earlier or later without some really serious equipment.
The ECU will actually by default take the requested SOI from the map, and if the EOI would be past the EOI limit, it advances the SOI until the SOI limit, after which if it is still not enough time to deliver the fuel, it cuts power.

So really, there is nothing that much to it. If you have bigger injectors, retard the SOI setpoint maps. If you have higher rail pressure, extend the "abbruchwinkel"...
If you think you're going to get anything else done without lab equipment, you're mistaken. The OEM is working on the last 1-2% because even 0.5% matters to them, you will never ever reach that level in the first place, nor does it matter.

It is actually a good idea to take the SOI setpoint angles from the engine you're lifting the injectors from.
The start and end limiters actually do not depend on the injectors at all. The first one almost only depends on the engine and the second one on the engine and the rail pressure.
The setpoint angles however mostly depend on the injectors, and less on the engine, especially if you calculate them as delta duration between "abbruchwinkel" rather than as an absolute value.

That's very clear & helpful, thank you   :o

I understand everything you said, but since i'm running E85, I have big cold post start issue with Porsche injectors, when it was far better with RS3 injectors and retarding SOI is not enough to fix  :-\.

I'll start tweaking near "abbruchwinkel" and report how is going  :)

Adjusting that will not help you. Read again what I wrote, that value is useless outside of WOT.
Most likely the injectors have a different / unsuitable spray pattern.

The only thing that will even change anything is most likely rail pressure.

Also chances are your problem is in ESUK...

He doesn't want to listen to us. ::)

Get an OEM file (suit to this injectors) and try to figure out the difference!

Start with basics: KLTVTSV, KLTIKRPR, FKKVS, KRKATE, TIMINHKS2, TIMINHKS1, TIMINP)!

https://www.hpacademy.com/previous-webinars/157-understanding-direct-injector-di-timing/

Very hard to do without a dyno to tell you if you are doing things correctly.

I don't agree with you. The first step is check MVB 32. ;)

Indeed, you don't need a dyno for most of this.
But of course the injector parameters/characteristics have to be correctly lifted over!
This is the first step. If these are wrong, everything else is a complete waste of time.

@Bitshifter
What is MVB 32 please ?
Edit : I guess it's measure value block n°32, which is related to LTFT

Since these injectors are coming with ECU Continental SDI4 / 8 / 9 it's hard to find something similar to Bosch maps.
I've tweaked KRKATE & FKKVS & KLTIKRPR in order to have LTFT & STFT near 0 at idle & WOT
TIMINHKS2, TIMINHKS1, TIMINP, KLTVTSV are stock for now.


I have an issue during WOT, as soon as high pressure is exceeding 145b, i have misfires, no problem when HPFP is 135 140b from 3500 to redline... STFT -3/-5, 6.8ms, 2500mbar absolute boost

Post a log!

Hi
Here are last logs.

38 39 40 measuring blocks were free in my SW so i've added what i wanted to log at the same time. You'll find STFT, Inj times, and interesting things inside.

MVB 91 is weird, it could be related to my misfires issue, since setpoint is not what is set in maps, and actual is not following setpoint  ??? . No DTC regarding intake camshaft .. Must be hardware issue, i will confirm with a near 100% stock file.

In 38 39 40 file, you will find D61 = +13.3% STFT, this is exactly when i got misfire during tests   :-[

Thank you guys  :)
 
Edit : PS : MVB40, what i called "Duty BP%" in my VCDS files is LPFP duty in %

If you are doing so advanced tuning I recommend you buy the single license for your car of my logger, it will make your job much easier with better logging.
https://docs.vehical.net/logger/help/ (https://docs.vehical.net/logger/help/)

I know it's not free etc, but it will save you so much time...

When you get misfires, check that low pressure is not dropping.
What PRV are you using, are you sure it's not opening at 145 bar?

Your car logger ?  :o Very good to know and well done for the achieved work, i will use it as soon as i've Tactrix.


About PRV, it's a 175b, and has always been working great. I spoke earlier about a relation between my misfires & rail pressure, but could it be related to the actual intake camshaft position ? MVB 91

My VVT issue could be related to an oil feeder obturated, as you can see on picture.
(https://i.gyazo.com/a88789c234303c5df7fd8457cedc3173.png)

Edit : VVT issue is related to the intake camshaft too advanced. Everything will be fixed soon...

Hi guys, nothing changed regarding misfire, but now VVT is fine !

So i tested with RS3 injectors, everything is ok ... I don't understand what's happening. I saw that Porsche injectors are shorter than stock & RS3, does any one got an issue while fitting Porsche ?

Thanks for this. This is very helpful.

So to clarify - changing KFWESBH will change the start of injection always - unless you reach one of the limitation maps?

I've been trying to smooth out a slightly lumpy idle with charge flaps disabled on my MED9.5 1.6FSI and retarding the injection timing a bit has helped so far.