# What injectors/tune on TT225 turbo?



## vtraudt (Mar 1, 2010)

What are you guys running on TT225 (K04-020) turbos with mods (upgraded IC, downpipe, no cat, cat back exhaust)? What tunes/files and injectors are out there?


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## wrparrish (Nov 13, 2008)

There is no reason to change injectors with a stock turbo and regular bolt ons when running regular fuel.

All of the stock turbo offerings from the regular companies like APR, Revo, Uni, or Giac, are all relatively the same.


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## vtraudt (Mar 1, 2010)

wrparrish said:


> There is no reason to change injectors with a stock turbo and regular bolt ons when running regular fuel.
> 
> All of the stock turbo offerings from the regular companies like APR, Revo, Uni, or Giac, are all relatively the same.


Meaning, that no one is trying to flow more than what the stock injectors can handle? I though by the time boost gets to 20 psi or above, the stock turbos would flow more than the injectors could handle.

Are those 365cc injectors (at 3 bar) (I think Bosch 0280155892)?


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## madmax199 (Oct 28, 2009)

vtraudt said:


> Meaning, that no one is trying to flow more than what the stock injectors can handle? I though by the time boost gets to 20 psi or above, the stock turbos would flow more than the injectors could handle.
> 
> Are those 365cc injectors (at 3 bar) (I think Bosch 0280155892)?


The OEM innjectors (386cc) are plenty for a stock turbo, even maxed out.
I have used the stock injectors in the past when I was on water injection only, at 4 bar of fuel pressure and 30 psi there was still some room to breath.

*I was getting 18.23 ms at 6000 rpm. *
IDC = (Avg Injector period/10)*(RPM/120) and that gave me 90% max at 6000 rpm.
Although it was not ideal they were not maxed out.


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## vtraudt (Mar 1, 2010)

madmax199 said:


> *I was getting 18.23 ms at 6000 rpm. *
> IDC = (Avg Injector period/10)*(RPM/120) and that gave me 90% max at 6000 rpm.
> Although it was not ideal they were not maxed out.


Can you explain the calculation? I have been asking myself the question what my injectors are actually doing. From 2600 rpm on, they are maxed out (at 16.32 ms shown in VAGcom) all the way to 6.5k rpm.

What does the equation mean? What percentage (normal is considered 80%) do MY injectors currently run (based on the 16.32 ms)?

Back to initial question: so the 386cc injector are plenty. The turbine (?) and the compressor also have plenty of power. Upping the power on the K04-20 then just means allow higher boost (are the common tuners going to 20 psi?) and getting the fuel right (stock and tuned run on 4 bar?).

Result is 300+ chp?


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## madmax199 (Oct 28, 2009)

vtraudt said:


> Can you explain the calculation? I have been asking myself the question what my injectors are actually doing. From 2600 rpm on, they are maxed out (at 16.32 ms shown in VAGcom) all the way to 6.5k rpm.
> 
> What does the equation mean? What percentage (normal is considered 80%) do MY injectors currently run (based on the 16.32 ms)?
> 
> ...


The calculation(injector duty cycle) is to find out at what percentage of their capability you are running your injectors. 
The injector duty cycle is the amount of time that the fuel injectors are being switched on and off. At 0% duty cycle, the injector is not on at all, and at a duty cycle of 100% or more, the injectors would be constantly on and maxed out. The duty cycle at idle is normally only a few percent, rising as revs or load increases - on the flip side if you lift off the throttle completely, from a load they close and your engine is a big air pump.

Your car at 16.32 ms, is running an IDC of 81.6%. What is strange, is that you mentioned that they are at 16.32 ms from 2600rpm to redline. Such a condition, under normal operation, is virtually impossible since the IDC rises up with load or revs. If your info is correct, that's a static condition that yould cause the car to go lean as the flow requirements are increasing and the injectors are only supplying a fixed amount of fuel. 

Stock injectors are enough(flow wise) from 3-4 bar on the stock turbo pushing up to 30psi (read my previous post again). Upping the power is not a simple up the boost and increase fuel. 

A)You need to have fuel that can take the heat and high cylinder pressures without knocking
B)You need a way to control the IAT because at 26+ psi the turbo is spitting out lava
C) If you are asking these questions you probably shouldn't try to mess with things.


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## vtraudt (Mar 1, 2010)

Madmax, thanks for the insight/explanation. What is the formula to calculate injector load from VAGcom injector time and RPM?

When I first logged the 16.32 ms constant (on 1.8T, K03/K04, chip and mods), I found it strange/alarming in deed myself. But now have seen lots of 'constant max' injector time logs from others. I don't have any lean codes, or misfires. But I am sure the stock injectors are causing the ECU to 'pull back' (via. waste gate valve duty cycle, timing, etc.?). Doesn't help that I have a uncommon "T.A.P. Stage 2" chip.

IAT do not climb over 37 deg C after several and long consecutive pulls. There was some timing retard logged for cyl 1-4 (up to 4.5 degree) from 3000 up. See log data below. 

I am trying to understand what the engine is doing. Unfortunately (nDBW/DBC!), with our ECU there is little to modify easily (=without $$$) (unlike for example on our Cougar Duratec engine, where it easy to modify the tune via simple uploads, for example to accommodate for larger injectors and other mods). 

What can be extracted from the data?


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## madmax199 (Oct 28, 2009)

A few things:
-The injectors are not maxed out at 16.32ms, and there must be something causing them(or any injectors behaving that way) to go static throughout the entire powerband(2720-redline).
I'd suggest some investigation to see what's causing that. As the revs and load go up, so does your fuel requirement and injectors as a result need to operate at a rising rate (in ms).

-The Mass Air Flow numbers are kind of low(toping 160G/s at 6240 rpm). Normal range for a healthy MAF is usually around 180 or more depending on the mods. Since the MAf is the sensor that the ecu looks at the most for its fueling, it may(or may not) be the reason your injectors are behaving the way they are.

-Everything else, besides the static IDC, looks OK. You do not have excessive timing pull, your wastegate duty is good. 

-I'd like to see your AFR curve. If you have a wideband car, do a log for lambda and another one for long and short term fuel trims and report.


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## Volksdude27 (Nov 25, 2005)

madmax199 said:


> A few things:
> -The injectors are not maxed out at 16.32ms, and there must be something causing them(or any injectors behaving that way) to go static throughout the entire powerband(2720-redline).
> I'd suggest some investigation to see what's causing that. As the revs and load go up, so does your fuel requirement and injectors as a result need to operate at a rising rate (in ms).
> 
> ...


if he isn't DBW he's probably not wideband

as for the injection time that sticks to 16.32 Ms I've seen that a couple times on cars that had the "ebay" chip AKA MAF resistor


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## madmax199 (Oct 28, 2009)

Volksdude27 said:


> if he isn't DBW he's probably not wideband
> 
> as for the injection time that sticks to 16.32 Ms I've seen that a couple times on cars that had the "ebay" chip AKA MAF resistor


AHH, a clamped maf signal would certainly explain the mistery:screwy:. What's beyond me is the fact that they resitor the MAF signal to a constant voltage. I could understand raising/lowering the signal throughout the range to force the ecu to dump/remove more fuel(like a different diameter maf housing would). IMO a contant maf signal to ecu, could result in a constant(static) fuel delivery making the car lean up top when the fuel demand is higher due to the revs/loads.

vtraudt, please post your AFR curve.


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