When I purchased the black Avant S4 I had in mind to continue modification efforts with it, and to return the Silver S4 back to a near stock condition for putting it up for sale.
One of the first alterations that I had made to the Silver S4 was to swap out the interior woodgrain door cards for the aluminum trim from my Santorin S4. Since the woodgrain door cards have the Bose speakers, and my Santorin S4 did not, I figured the woodgrain with Bose speakers would be preferable when the car is to be sold.
So today I swapped out the driver’s side door cards, reinstalling the original woodgrain style.
Today I conducted a flow test comparison of a pair of RS4 MAF’s and an EPL MAF housing.
For some time I’ve wondered how much, if any, restriction the screen on the RS4 MAF housing causes. A parts car that came through the garage was equipped with a Bosch MAF housing that is the same size as the Bosch RS4 MAF but had a set of screens that are removable.
MAF housing lineup
I decided I would pull the RS4 MAF from my car along with the RS4 airbox top and stick them on the flowbench with the rest of the stock intake to see how the screen affected the airflow through the intake. I also decided I would retest the EPL MAF housing attached to the stock airbox top as that combination had out-flowed the RS4 MAF and RS4 airbox combination previously.
The results of the flow test are shown below:
Interestingly the removal of the screen from the RS4 MAF provided only a little benefit. The EPL MAF and stock airbox still provided a little more airflow than the screen-less RS4 MAF and RS4 Airbox top. All tests were conducted with a stock air filter, modified lower airbox (Darintake modification), and the snorkel attached.
I also have a large K&N cone filter available, so I attached the RS4 MAF to the K&N filter and retested using the RS4 MAF housings.
The results of this test are shown below:
The removal of the screen from the RS4 MAF housing produces a larger increase in airflow with the K&N filter versus the RS4 MAF with the screen in place.
More dramatically, the K&N filter allows for much higher airflow at the test depression of 10″ of H2O.
A couple of things should be noted, first is that a test depression of 10″ of H2O is not very much pressure. In these tests there is a substantial amount of airflow passing through the intake with minimal pressure drop. It’s common to test at 28″ of H2O, nearly three times the level this test was conducted at. This test was performed at 10″ due to a bench limitation of around 600 CFM.
From this test it would seem that the K&N cone filter would be a desired substitute for the stock intake. What this test does not account for is the potential disruption of airflow over the MAF sensor caused by the cone filter, which could lead to tune problems.
Nor does it show how engine compartment temperatures may alter intake air temperatures with the cone filter.
After loading a revised tune onto the car’s ECU I took a short drive and had a couple of alert lights come on the gauge cluster. I plugged in the XTool to see what the problem was and the device could not connect with the ECU.
I decided I should return home, but now the car would not start. I had to pull a MacGyver to get the bolts out of the ECU box, and then I disconnected the ECU, re-connected it, and then was able to start the engine to return home. Upon arrival I hooked up VCDS and received the following alerts:
18010 – Power Supply Terminal 30
P1602 – 35-00 – Voltage too Low 16985 – Internal Control Module P0601 – 35-00 – Memory Check Sum Error
The second one I had never seen before, but I immediately thought that maybe I hadn’t created a checksum on the latest bin that I had loaded on the ECU. Looking in the folder with the development tunes I saw the latest file name lacked a CS at the end of the name, my indicator that the (C)heck (S)um had been set. Doh!
It took unplugging the ECU for a while before I could get Nefmoto to connect to it, but finally it did and I was able to write a corrected file.
Lesson learned about staying vigilant when installing files on the ECU.
