2004 Chevy Cavalier Engine Revs Up

Tiny
KOALASR4U
  • MEMBER
  • 2004 CHEVROLET CAVALIER
  • 4 CYL
  • 2WD
  • AUTOMATIC
  • 51,800 MILES
While driving at a constant rate of speed, whether in town (40 to 45 mph) or on interstate (65 to 70) the engine will rev up anywhere from 300 to 600 rpms then after a second or two drop back to normal. The car is not bogging down or anything, just kind of wants to take off with you. Feels a littly like car wants to go into overdrive like for passing. Problem is intermitten but getting worse.

Firestone checked it over, said it sounds like transmission. The car has a totally enclosed transmission, one of those with no dip stick to check fluid level.

The only thing they could see was there is a seal where the tranny fits with rear axle (gears? Etc) and that it has a slow leak there. They suggest pulling rear axle and repairing this seal then refilling tranny thru some small hole. They think tranny is low on fluid and that is why the car is reving up like that.

Does this sound right? Does anyone have any advice or other ideas?

No check engine light on. Everything else running smooth, car as a whole running smooth.
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Tuesday, January 20th, 2009 AT 3:20 PM

3 Replies

Tiny
MMPRINCE4000
  • EXPERT
It sounds like the TCC lockup is engaging and disengaging. After a certain speed the TCC will lock the convertor and rpm will drop 300-600 rpm.
The car will generally have to be in closed loop for this to occur, so it may be a bad thermostat causing the TCC to disengage because coolant temp is too low (this is one of many possibilities, just an example).

I prefer an independent trans. Shop as opposed to a chain. A shop that does the trans. Repair in-house.

My advice is get a second opinion.
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Wednesday, January 21st, 2009 AT 9:34 AM
Tiny
KOALASR4U
  • MEMBER
Vehicle temperature is running normal according to guage. I have not noticed any differences there. Car is not dropping rpm's but reving up the 300 too 600 then dropping back to normal.

Any other ideas?

What is a TCC?

Thanks again!
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Wednesday, January 21st, 2009 AT 10:58 AM
Tiny
MMPRINCE4000
  • EXPERT
The TCC is torque convertor clutch, when it engages, rpm will drop 300-600, when it disengages rpm will rise 300-600 rpm. Coolant temp. Is one factor, so is brake switch (when depressed TCC will disengage), so if brake switch is bad, TCC will not function properly.

Since this is an intermittent problem, I would suspect the TCC vs. A slip, but it is possible, and since it drops and rises a specific RPM (a slip would not rise/fall a specific rpm), that again points to TCC.

I would get a second opinion and ask about the TCC as a possible cause.
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Thursday, January 22nd, 2009 AT 9:10 AM

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