Background:
This post continues a series where Stage 2 tune options for the Mk7 GTI are compared.
In this post an IS20 Stage 1 tune from Audi Performance and Racing (APR) is installed on the Mk7 GTI and engine and vehicle performance data are recorded for comparison with stage 2 tune options.
The inconsistency between saying the APR Stage 1 tune and comparing it with other Stage 2 tunes is not a mistake. APR does not offer a Stage 2 tune within the United States; therefore, the only tune option I can use to compare with the Stage 2 tunes is the APR Stage 1 tune.
The GTI is equipped with a Baun Performance catted downpipe that uses a 400 cpi GESi catalytic converter. Even though this is a high-flow cat it does not trigger a cat efficiency code when using a tune made for the stock downpipe.
A comparison of the PUT and PUT Setpoint shows there is a slight amount of over-boosting taking place.
APR offers a home flashing option via their UltraLink, but for my purposes taking the GTI to a nearby APR dealer to install the tune was a better option.
Test procedure:
Information about the data collection procedures is found on the main test page.
APR Stage 1 Test Results:
An overview of one data collection session is shown below to illustrate how the data was recorded:
The next four charts show the typical changes in engine operating variables as engine RPM increases during multiple third-gear full-throttle pulls.
The air-to-fuel ratio is shown with the red lines and the intake air temperature with the pink and purple lines.
Boost (red lines) and turbocharger wastegate duty cycle (pink and purple lines):
The Ignition Timing Advance (red lines) and occurrences of ignition timing retard [none] (yellow, green, and pink lines):
Low-pressure fuel pump duty cycle (red lines) and fuel rail pressure (pink and purple lines):
APR Stage 1 vs Other Stage 2 Tunes:
The next chart shows the same data in a different format. APR is where the blue arrow is pointing.
The next chart shows the same Acceleration Time data in a different format. APR is where the blue arrow is pointing.
Conclusion:
The APR Stage 1 ECU tune was installed on a Mk7 GTI equipped with a Baun Performance aftermarket downpipe to record street performance data.
The data from the APR Stage 1 tune was compared with aftermarket Stage 2 tunes.
APR’s Stage 1 tune compares favorably with the Stage 2 tunes that were also tested.
I have occasionally encountered other enthusiasts claiming that APR’s tune is “weak”, “garbage”, “outdated”, etc. Evidence collected using my Mk7 GTI does not support these claims.
On the contrary, the street data measures show that the APR Stage 1 tune is comparable to several popular Stage 2 tunes.
Great work. For chart clarity, instead of legends, just put the names in the bars.
Thanks for the suggestion on the chart, they are getting harder to read quickly.
Do you know what cell count the stock downpipe is ? Preferably the primary cat. I can’t find this information anywhere. I had my secondary cat taken off and would like to know how that compares to the baun, unitronic or any gesi catted dp, even just in theory or your opinion. I was APR stg 1, now have the DTR 6054 with APR stg 3 tune based on the primary cat being there. Anyhow , thanks
I do not. My guess is 400. Other factors to consider are the length of the catalyst and the diameter since they will also contribute to the amount of back pressure generated.
Hello Jeff,
Very interesting testing thanks, is there some reason you didn’t include the knock retard testing this time around?
Hey Dan, thanks! Yes, since the tune is a Stage 1, made for use with a stock downpipe, and I used the Baun aftermarket downpipe, and I was seeing indications of having a bit of over boosting throughout the pull, I was concerned that getting into the fine details of comparing it with the other Stage 2 tunes may give an inaccurate picture of how it compares. That’s why all of the charts where engine operating values of the various tunes are compared have also been omitted from the APR post.