Recently, I thought my car may be running at a slightly lower RPM than normal. Today the rpms were definitely lower. I was driving at about 65mph and they were at about 1500, which is about 5-600 lower than usual. Just seems that, in general, they are lower when cruising. They jump up to between 3-4000rpm when accelerating like they normally do but the cruising idle is much lower. Car has 260k on it and otherwise, runs great. Its an LE and has regular oil changes at 3k. I have never had it tuned up and purchased it at 170k.
Any suggestions would be great.
Not sure how that is possible, even in top gear the RPMs at 65 MPH shouldn’t be that low. Either the tach is reading incorrectly, or the torque converter isn’t locking up and the transmission is slipping dramatically.
Also, Have you at least changed the timing belt at some point?
16 year old vehicle with 260000 miles. If it starts and gets there and back I would not even worry about what the RPM gauge shows. Now if you start to take off and the RPM’s jump up and you don’t seem to go anywhere then worry.
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A possibility:
There’s a button on your shifter labelled “O/D.” If you turn it off, it will not shift into the highest gear, which means the RPMs will be higher than normal while driving on the freeway.
If, perhaps, you’ve been hitting this button, or the button has/had some sort of gunk in it that was making contact when it shouldn’t have been, then you may have been driving along all this time without overdrive.
Now, for whatever reason, overdrive is working again and you are seeing the appropriate RPM drop as a result.
You can test this by getting it out on the highway, getting it to 65, noticing the RPM being “too low,” and then pressing the O/D button - does the RPM jump up? Then that was the issue.
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+1 to shadow’s post.
Many years ago my mom called me because her Protégé was making too much noise on the highway. We took a ride. I had her press the overdrive button and it immediately quieted down. Turns out my sister had borrowed it and for some reason left the OD off. My mom, being elderly, didn’t know about the OD button.
1500 RPM is going to be too low. Top gear in that car (assuming it’s 4 cylinder automatic) is .706 , the axle ratio is 3.717 . The tires are about 24.7 inches tall. That works out to about 2300ish RPM at 65 MPH in 4th gear. If the tach is reading 1500 RPM something is amiss.
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Just make sure you’re really really going 65 mph (55 seconds elapsed between mile markers).
The next time you feel the RPM’s are too low, smack the top of the dash with the palm of your hand.
If the RPM’s read normal, it’s the driver motor for the tach.
Speedometers will do the same thing.
Tester
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This sounds like a problematic tach display rather than a problem w/the engine or transmission. If it seems to be running ok otherwise, the easy solution is to just ignore the bogus tach.
There is no way for a car to be revving lower than normal at 65 unless you have been driving with overdrive off
and somehow turned it back on. There are transmission or clutch problems that can make it rev higher but none than can make it rev lower. At 260,000, just ignore the tach.
It doesn’t do anything useful in that xar anyway.
Could be a bad battery or the alternator is not providing enough amps, causing RPMs drop under electrical load.