More fuel for the fire.We've tested the RS4 injectors during our 2.0T turbo development R&D.
We first tested them in cars, before we purchased our $8000 ASNU DI injector test stand.
When in the car, they produce what looks to be much richer air/fuel ratio vs stock or S3. However, after careful analysis, some odd starting and part throttle behavior was traced to their use.
Upon testing stock, S3, and RS4 injectors in our ASNU test stand, we had some interesting results.
As you can see from the photo below, the spray pattern of the RS4 injector is very different from the stock and S3 injectors. This alone can contribute to the starting and part throttle issues:
What was even more interesting were the measured flow rates:
Stock = 1080 cc/min
RS4 = 1091 cc/min
S3 = 1217 cc/min
For all intents and purposes, the RS4 injectors flow about the same as stock 2.0T FSI injectors. This makes sense when you do a hp per cylinder calculation between the two engines. We also confirmed our results after contacting Hitachi directly.
The rich air/fuel exhaust reading seems to be an anomaly possibly related to incomplete combustion due to the wrong spray pattern. The peculiarities of direct injection behavior vs conventional injection behavior are still being learned.
Either way, the exhaust gas readings are a false positive as confirmed by our bench testing. Unknowingly, software tuners may be pushing things way leaner than they intended just going off of wideband readings!
What we also found is that a mass marketed transverse K04 kit out there is indeed using RS4 injectors. We had a client come to us with running issues, and a first hand test of his injectors confirmed this.