I took my Cherokee on a short (140 mile) trip the other day and noticed that at 70 mph, the tach is reading about 2250 RPM. I have a 3.55 axle ratio and 31s, so I should be seeing closer to 2000 RPM at that speed. The transmission is an AW4 automatic and I'm accounting for MPH variation due to the tires.
The torque converter locks up normally, if a bit early at lower speeds (a common complaint, from what I've read). Since this is the case, there wouldn't be any fluid slippage, so the 2000 RPM calculation should hold true. Any possibility as to why I'm seeing higher engine speeds? I know the factory gauges can't be totally trusted, but 250 RPM is a lot to be off by.
Other operation seems fine... no noticeable slipping around town, it goes fine when given gas, and I replaced the filter and fluid in the pan about 4000 miles ago. The neutral safety switch checks out against the FSM diagram, too.
The torque converter locks up normally, if a bit early at lower speeds (a common complaint, from what I've read). Since this is the case, there wouldn't be any fluid slippage, so the 2000 RPM calculation should hold true. Any possibility as to why I'm seeing higher engine speeds? I know the factory gauges can't be totally trusted, but 250 RPM is a lot to be off by.
Other operation seems fine... no noticeable slipping around town, it goes fine when given gas, and I replaced the filter and fluid in the pan about 4000 miles ago. The neutral safety switch checks out against the FSM diagram, too.