low rpms at 60 mph

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teejay1999

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my manual 02 sunfire started to slowly overheat at 70 mph, cools down at 60mph but the rpms seem too low... it cruises at about 2100 rpms, if I drive at about 50 mph its too high on 4th gear(2800) and if I drive it on 5th gear its too low(1900), any suggestions?
 
Are you inquiring about the overheating or your RPM numbers at a given speed?
How are you deciding that your engine speed versus rpm is wrong?
Was it different in the past?
Did you check your coolant level when cold?
Is anything blocking your radiator?
Do your engine fans run?
Do your engine fans come on with the AC turned on?
 
Thanks for replying... Yes the rpms were slightly higher about a month ago. I replaced almost the entire coolant system about 2 years ago when i got the car, water pump, thermostat, hoses, radiator, fan and temp sensor. nothing wrong just did it as a precautionary maintenance. And yes the fan works and it turns on when the ac is on and coolant level seems normal when cold ... I check it every other week or so.... My concern is the low rpms rather than the overheating cuz it never actually overheats
 
You would have to confirm the accuracy of your tachometer with a handheld unit. There is nothing mechanical that will cause a low rpm reading. A slipping clutch will cause a high rpm.
I'm assuming you haven't installed different tires.
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As a matter of fact I did.. i changed out struts and shocks some time ago ... But i had to change the front recently because i didnt do alignment at the time and the front 2 were really worn out, the back 2 however were good and did pass my state inspection ...
 
Well you have your answer then, the tires.
Are the new ones the same size?
 
They are but
melsg5 said:
Well you have your answer then, the tires.
Are the new ones the same size?
Click to expand...
Ill assume very different wear stages ... Ill rotate them today and hopefully see improvement. Thank you very much for your time and ill update you either way
 
teejay1999 said:
They are but

Ill assume very different wear stages ... Ill rotate them today and hopefully see improvement. Thank you very much for your time and ill update you either way
Click to expand...
Why would you do that?
Lower engine speed, better gas mileage.
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