To confirm your cats are PLUGGED up. Tap into a good source of intake manifold vacuum and insert a Vacuum gauge.
- Read engine vac at idle
- Read at 1500 RPM (no load required)
- Read at 2500 RPM again no load required
If you vac number drop as RPM increases, your down stream exhaust is indeed blocked. Drop the cats and see if the number change, because a collapsed pipe and or muffler further down stream will give you similar results.
If you are really ambitious, there are pressure gauges and lines that can be screwed into the O2 ports upstream and downstream of the cats to see the drop live.
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2005 X5 4.8IS
The
Blue ones are always FASTER....
Current Garage:
2005 X5 4.8is
2002 M5 TiSilver
2003 525iT
1998 528i
Former Garage Stable Highlights
2004 325XiT Sport
1973 De Tomaso Pantera, L Model
1970 Dodge Challenger T/A 4 sp Alpine White
1970 Dodge Challenger T/A 4 sp GoManGo Green
1971 Dart Sport, “Dart Light” package
1969 Road Runner 383
1968 Ply Barracuda 340S FB Sea-foam Green