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Discussion Starter #1
I drive a 1995 4.0 SSE. It is supercharged and has 3" exhaust with no cats. I just recently removed the heads and had them gone through and prepped to Callaway flow specs then decked for true. I put it back together with composite gaskets and cleaned and sealed everything on my way out. She ran really well for a while but now has what I would call a "poor" idle as well as a knock and lots of black smoke when pushed. She seems to be running very rich and mpg's are down I always run premium fuel. Cylinder compression checks show no problems and the OBD II computer shows no fault codes (I use an Actron computer which actually reads codes and erases on my 95). Would love some input.
 

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1995-2002 Range Rover P38A
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Interesting. Curious what fuel injection and timing modifications had to be made to run the supercharger? I'm also surprised that with knocking and running rich your not throwing a code, although I guess O2 sensors can malfunction without throwing a code... which could be what's happening.
 

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It is an Eaton MP90s supercharger with a custom intake and Throttle body. Four wheel drive dyno showed 82 horsepower and 87 lb feet of torque increase (from published factory n/a motor). The torque increase comes on at a great low rpm. It really bring this motor to life. I will also point out that once I tore the top end apart I DID NOT notice the signs that some (not to mention names) british engine builders showed as a weak point in supercharging-uneven distrobution of boost. The reason for a rebuild was due to an overheat by the previous owner-the radiator was 90% blocked with "stop leak". I also have o2 simulators on the rear cats so the sensors are sending signals to show cat efficiency as good. I still have to do some further checking since some of my poor running problems have started after I chased down a misfire due to a split wire in the loom coming from the GEMS unit and going to the last coil on the drivers side. Four wires were founf to be severely comprimised as they were rubbing against the upper belt tensioner. Oh well another day of fun hunting down some lucas gremlins.
 

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Discussion Starter #5
I am going to go ahead and replace the two primary sensors since they seem original (114,000 miles).
 

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where'd you get it and how much did it cost? and what else did you have to do to install, -or did you buy it that way (previous owner comment....)
 

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1995-2002 Range Rover P38A
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On turbocharged cars, the symptoms described are indicative of an air leak in the compressed air section of the intake -- metered air doesn't match what actually ends up in the combustion chamber. In the end, this will result in the engine running rich.

Something worth checking. In that regard, supercharging is no different.
 

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Discussion Starter #9
excellent point. I have a 944 turbo and of course there is alot of plumbing on the cold side that can leak. My supercharger sits directly on the intake so there is little to leak but that doesn't mean that I may not have blown the gasket material out.
 
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