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)
33 - (A/C clutch - no A/C on this vehicle)
51 - (running lean)
55 - (end of diagnostics)
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
. When throttle is let up to under 1/2 power is restored if the RPM is under 2,500
Any suggestions as to the problem?