Still digging for answers

After pulling off the passenger side intercooler the charge pipe coming off the compressor housing looks fine:

clean_outlet_pipe

And looking at the catalytic converter for the passenger side it’s looking fine as well:

clean_catNext up is the motor coming out so that I can visually inspect the passenger side turbocharger.

 

That’s not good

While driving the other night I heard a bang sound followed by a drop in power.  Subsequent the car sounded a bit different.  Initial investigation showed that one of the two wideband O2 sensor bung plugs in the downpipe had come out.

That plug coming out seemed like an odd cause for dropping power so I continued to investigate.  An intake pressure check was good, I tested the wastegate lines and they were good.  When the car was idling there was no smoke or visible water vapor coming from the tail pipe.

I was still suspicious of a possible turbo problem so I hooked up separate pressure sensors to each compressor housing signal line and then went out to record the pressure in the turbo compressor housing.

compressor_comparison

The results are shown above.  The great disparity between the driver side and the passenger side (driver side is blue and passenger side gray), and neither matching the MAP sensor, has me concerned that the passenger side turbo may have failed.

Logging Exhaust Gas Pressure

Hooked up the pressure sensor to the exhaust manifold once again to measure the pre-turbine pressure.  I have not confirmed that the pressure sensor is properly calibrated, but the results shown below are probably in the ballpark.

The EGT is flat line because that is a probe located external to the exhaust manifold with the purpose of measuring the temperature near the surface of the exhaust manifold.  With a small air gap between the sensor and manifold surface, and 40 deg outside air to cool things, the region near the exhaust manifold was not very hot during this pull.

Exhaust gas pressure chartHere is the setup I am using to log the exhaust gas pressure.

 

Audi B5 S4 Information and Testing