At freeway speeds the tach is jumping 200 RPM's

Tiny
CALEBERICKSON
  • MEMBER
  • 2000 CHEVROLET BLAZER
  • 160,000 MILES
I have a 2000 Chevy blazer and when I get to around 60-75 mph the rpms start to jump 200 rpm. Could this be a transmission problem? Happens at 60-75 mph
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Sunday, December 11th, 2011 AT 5:51 AM

12 Replies

Tiny
JACOBANDNICKOLAS
  • CERTIFIED MECHANIC
Most likely not. If the check engine light has come on, have the computer scanned for trouble codes. A bad trans will slip at any speed. My guess is there may be a bad throttle position sensor or something like that.
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Sunday, December 11th, 2011 AT 5:55 AM
Tiny
CALEBERICKSON
  • MEMBER
I have p1870 transmission component slipping code showing. Doesn't slip bad though. I was reading up and some were saying possibly torque converter acting up locking and unlocking. I was also thinking of a throttle position sensor going out
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Sunday, December 11th, 2011 AT 6:01 AM
Tiny
JACOBANDNICKOLAS
  • CERTIFIED MECHANIC
200 RPM's would be hard to notice if it wasn't slipping. WHen the RPM's increase, do you feel the vehicle accellerate at all?
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Sunday, December 11th, 2011 AT 6:10 AM
Tiny
CALEBERICKSON
  • MEMBER
Yes when it jumps up and down it will***** a bit. Gets very frustrating driving on highway
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Sunday, December 11th, 2011 AT 6:16 AM
Tiny
CALEBERICKSON
  • MEMBER
Pull forward and back
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Sunday, December 11th, 2011 AT 6:25 AM
Tiny
JACOBANDNICKOLAS
  • CERTIFIED MECHANIC
That leads me to believe the trans isn't the problem. Try having the computer scanned for trouble codes. Most parts stores will do it for free. I think it may be engine related. Also, check to make sure the trans fluid isn't burnt, low, or really dirty.
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Sunday, December 11th, 2011 AT 6:30 AM
Tiny
CALEBERICKSON
  • MEMBER
Only codes present when scanned was the p1870. Transmission component slipping.
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Sunday, December 11th, 2011 AT 6:33 AM
Tiny
JACOBANDNICKOLAS
  • CERTIFIED MECHANIC
IS the trans fluid clean and full?
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Sunday, December 11th, 2011 AT 6:45 AM
Tiny
CALEBERICKSON
  • MEMBER
I need to check the fluid. Possibly low. I also have a bad thermostat that im going to fix would that have anything to do with the lurching? Being that the engine is not getting to normal operating temp?
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Sunday, December 11th, 2011 AT 6:53 AM
Tiny
JACOBANDNICKOLAS
  • CERTIFIED MECHANIC
No to the temp, but yes to the low ATF.
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Sunday, December 11th, 2011 AT 7:03 AM
Tiny
CALEBERICKSON
  • MEMBER
Ok thanks. So possibly could be due to low tranny fluid and slipping at higher speeds
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Sunday, December 11th, 2011 AT 7:09 AM
Tiny
JACOBANDNICKOLAS
  • CERTIFIED MECHANIC
Yes, low fluid can lead to low fluid pressure allowing the clutch pack to not be locked.
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Sunday, December 11th, 2011 AT 7:30 AM

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