What affects RPMs?

Jul 04, 2005 7 Replies

First reply

Andy Warren

Torque converter clutch not locking up on a 700R4 auto trans is what you're describing. To see if it is locking up, (driving in 4th gear of course, not coasting), slightly press the brake pedal enough to make the brake lights come on. The RPM should increase about 250 rpm on…

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K

I've been noticing that my RPMs can differ as much as 300RPMs at the same speed... why is that?



And it doesn't seem like T-tops on or off is a factor...



Went on a trip yesterday... 340 miles one way with the t-tops off and the windows down.. made 28.6 MPG... came back the same trip windows up and t-tops on made 27.8 MPG... weird



I noticed going up at 70, RPMs were 2200... but on the way back at 70 it was at 2500+. I thought that was weird. Any thoughts?


-Geno



1985 Blue Camaro 2.8L auto w/T-tops (aka "Tazmaro")
1988 Blue Firebird Formula 5.0L auto w/T-tops
1985 Brown Firebird 5.7L (360) 5-speed NO T-tops (still looking for an '82 Black T/A w/T-tops)
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T

It wasn't uphill coming back was it ?

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D

Sounds like the torque converter isn't always locking up.

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T

LT-1 with a 6-speed - 2500 rpm in 6th will get you about 100. 2000 is

6th is worth a shade less than 80.

Tom

97 Formula Convertible, Red LT-1 w/6 speed
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S

A tail-wind versus a head-wind?

I know thirdgen f-bodies have decent aerodynamics even by today's standards but that's got to make a difference.

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K

Lol.. no.. I was noticing it the whole way... and it was the exact same trip... mostly flat roads...

-Geno

1985 Blue Camaro 2.8L auto w/T-tops (aka "Tazmaro") 1988 Blue Firebird Formula 5.0L auto w/T-tops 1985 Brown Firebird 5.7L (360) 5-speed NO T-tops (still looking for an '82 Black T/A w/T-tops)
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U

I'd say your lock up torque converter isn't always doing it's job.

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