05-20-2012, 10:37 AM
Officially Welcomed to the 'Fest
Join Date: Sep 2004
Mein Auto: 335d
Here's some info from BMW on the EGR in the U.S. E90:
Those first 3 items (electric valve, sensor, cooler) make me believe that our EGR is significantly different from the Euro EGR, so we need to tread carefully. I have an image of our EGR part (including the cooler), but I haven't been able to figure out how to get it posted yet.
Compared to the European version, the high pressure EGR is equipped with the following special features:
• Electric EGR valve with positional feedback
• Temperature sensor before high pressure EGR valve
• EGR cooler with bypass.
The electric actuating system of the EGR valve enables exact metering of the recirculated exhaust gas quantity. In addition, this
quantity is no longer calculated based solely on the signals from the hot-film air mass meter and oxygen sensor but the following
signals are also used:
• Travel of high pressure EGR valve
• Temperature before high pressure EGR valve
• Pressure difference between exhaust gas pressure in the exhaust manifold and boost pressure in the intake manifold.
This enables even more exact control of the EGR rate. The EGR cooler serves the purpose of increasing the efficiency of
the EGR system. However, reaching the operating temperature as fast as possible has priority at low engine temperatures.
In this case, the EGR cooler can be bypassed in order to heat up the combustion chamber faster. For this purpose, there is a bypass
that diverts the flow of the exhaust around the EGR cooler.
This bypass is actuated by a flap which, in turn, is operated by a
vacuum unit. The bypass is either only in the "Open" or "Closed"
Last edited by 62Lincoln; 05-20-2012 at 10:40 AM.