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Roving.Richard 02-12-2011 12:17 PM

Power loss above 1/2 throttle, code 51
My 1995 2.5L YJ (165,000 miles) suddenly lost power above 1/2 throttle.
While climbing a hill the exhaust note changed (got deeper with a sound like a turbo bearing failing) and after about 2 minutes the check engine light came on and stayed on until the engine was shut down.

I noticed that there was also a loud exhaust rattle at idle and above half throttle there is a whistling/turbo bearing noise (the engine in non-turbo) after this started.

Engine codes were set and they are:
12 - (Battery had been disconnected) :rolleyes:
33 - (A/C clutch - no A/C on this vehicle) :banghead:
51 - (running lean) :surrender:
55 - (end of diagnostics) :p

I've replaced the Fuel Filter.
Fuel Pressure is 35 psi running; 37 psi key on, engine off.

Power is OK up to about 2,500 RPM or 1/2 throttle. Above this there is rapid power loss :confused:. When throttle is let up to under 1/2 power is restored if the RPM is under 2,500 :facepalm:

Any suggestions as to the problem?

Roving.Richard 02-12-2011 03:28 PM

Problem Solved
:dance: Fixed! Problem was the Catalytic Converter.
The guy at the muffler shop said it was good that I didn't push the engine too hard or long as the result of that is a blown head gasket from the high back pressure and temperature.:whistling:


bc3_Jeep 02-12-2011 04:26 PM

I was gonna suggest that......but you beat me to it..... :))

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