I need some help diagnosing a knocking noise from from motor, because I have no idea where to start. My car is a '97 with about 125,000 miles on it. There are two codes from the ECU, P1131 and P1151, which indicate lean readings from the upstream O2 sensors.
About two weeks ago I noticed my car started running rough when stopped at lights, there was a low rumbling/knocking noise and vibration. This would stop as soon as I shifted it to neutral, reverse, or park. The noise and vibration would also stop as soon as I let off the brake.
Around the same time, I accelerated pretty hard (~3k RPM) and heard a terrible knocking/clunking/bearing rattle noise and the car had very little power. I haven't pushed it that hard since then, but I can hear the noise starting when I get up past 2k RPM.
The problem has gotten worse, shifting it out of gear no longer stops the noise all the time. I can hear the noise now when accelerating from a stop and even cruising at around 1-1.5K RPM. I have also noticed it is worse when facing uphill. Rocking the car back and forward in park will also make it knock.
Any ideas at all are welcome. I have always done all the work on this car myself but I'm thinking I'll need to take it in after thanksgiving, because I don't know where to start trying to find the problem.
About two weeks ago I noticed my car started running rough when stopped at lights, there was a low rumbling/knocking noise and vibration. This would stop as soon as I shifted it to neutral, reverse, or park. The noise and vibration would also stop as soon as I let off the brake.
Around the same time, I accelerated pretty hard (~3k RPM) and heard a terrible knocking/clunking/bearing rattle noise and the car had very little power. I haven't pushed it that hard since then, but I can hear the noise starting when I get up past 2k RPM.
The problem has gotten worse, shifting it out of gear no longer stops the noise all the time. I can hear the noise now when accelerating from a stop and even cruising at around 1-1.5K RPM. I have also noticed it is worse when facing uphill. Rocking the car back and forward in park will also make it knock.
Any ideas at all are welcome. I have always done all the work on this car myself but I'm thinking I'll need to take it in after thanksgiving, because I don't know where to start trying to find the problem.