: Transmission/Engine Question.



Jneedom14
07-23-13, 11:26 PM
I have a 2006 Cadillac STS V8 N* now when im at high way speeds should my engine be running at about 2k RPM keep in mind im running lean so would that have anything to do with it and could it be the transmission not shifting into the appropriate gear that could cause the high rmp at highway speeds.

curtc
07-23-13, 11:29 PM
That's about what mine runs at 70mph...

Jneedom14
07-23-13, 11:36 PM
Okay i just thought it was a little weird for it to be like that....And my intake manifold bolts are good so it must be something else causing me to run lean

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and what kind of transmission is in our cars

mckellyb
07-24-13, 08:30 AM
5L50E, it was a joint design with BMW...turns out diesel Range Rovers use the 5L40E, and the 50 is a beefed up version of the 40E.

You think it revs high, now, huh? The 4th-5th solenoid in my transmission finally died, and 4th gear, while peppy, makes for about 2,800 RPM @ 65.

It is quite responsive, however.

Jneedom14
07-24-13, 12:09 PM
How much to replace that solenoid.

mckellyb
07-24-13, 01:38 PM
The part is about $25. I'm going to do all four solenoids, three shift solenoids and the torque converter one, a filter, and rubber gasket for about $150, shipped. All shipped Priority Mail, 'cause I want to fix it this weekend.

To have it done, I have no idea, as you have to pull the pan and the valve body. I may use this to put a final six quarts of fresh Dexron VI into it, too, and that's an extra $37, or so, from Amazon (with Prime, so no shipping...it's like cheating, but I Amazon enough for it to more than pay for itself).

Jneedom14
07-24-13, 04:42 PM
Okay my engine is at 2K at like 80-85 so i guess its normal. And i cant diagnose my lean condition.

EChas3
07-24-13, 10:47 PM
Take it to a dealer and be done with your problem.

Charles Warren
07-25-13, 11:37 AM
2000k at 75 mph sounds normal and mount could be broke who knows, more info would be needed to tell you whats wrong

1BadCadSTS
07-25-13, 11:40 AM
Don't forget there's 3 different axle options which will determine cruising speed. 2.73 3.23 and 3.42

Ludacrisvp
07-25-13, 12:07 PM
I wish I could be at 2k RPM going 80-85MPH, I'm like 1800/1900 RPM at 65MPH and probably about 2400? at 80MPH. I'd have to go for a drive to find out again for sure though.
Mine is GU5 (3.23:1) which I understand to be the only option for the AWD model.

1BadCadSTS
07-25-13, 12:45 PM
I wish I could be at 2k RPM going 80-85MPH, I'm like 1800/1900 RPM at 65MPH and probably about 2400? at 80MPH. I'd have to go for a drive to find out again for sure though.
Mine is GU5 (3.23:1) which I understand to be the only option for the AWD model.

Correct. Unless you swap to srx v6 diffs. Those had 373s. Of course that will net worse mpg over the 323.

Ludacrisvp
07-25-13, 01:01 PM
Correct. Unless you swap to srx v6 diffs. Those had 373s. Of course that will net worse mpg over the 323.
Which I assume was done to improve the acceleration characteristics of the V6 model?
I have to wonder if one could swap out to using the LSD 2.73 diffs in lieu of the current 3? open diffs in the STS4

1BadCadSTS
07-25-13, 01:16 PM
You could but you would need a tune for it and would have to do both front and rear diffs.

Correct the v6 was given the 373 to help acceleration. I believe the also had 390s but I'm not sure. I just know my sisters 05 awd v6 sport has 373s.

EChas3
07-25-13, 10:22 PM
All the AWD's (V6 & V8) had 3.23 final gears, right? I know fleet & rental V8's in 2007 came with 2.73. 3.42 was the hottest final gearing and I thought it was standard on the RWD 1SG & optional on the 1SF. Although I don't know why, I had the idea that all the early (non-DI) V6's were 3.23. I'm sure some gear would have helped it off the line. Even later V6's were at a major disadvantage in torque, which is a better indicator of performance in a 2-ton touring sedan.

My 2006 V8 AWD 5-speed turns 2K RPM doing 60MPH on 235/50R18's (virtually the same circumfrance as the OEM 255/45R18 rears.) To the extent I'm right, all AWD's would do so as well; maybe the early V6 RWD's, too. My wife's 2007 V8 RWD 6-speed has the 2.73 and 2K RPM has us cruising at 80 MPH on the stock wheels & Summer Conti DW 235/50R17 tires.

Ludacrisvp
07-25-13, 10:36 PM
At 80 in mine its basically 2300rpm

Sent from my One

EChas3
07-25-13, 11:31 PM
Something else is different between our cars.

you posted: I'm like 1800/1900 RPM at 65MPH

But 2,000 RPM puts me at 60 MPH; maybe 61 but no way am I under 2,000 RPM when running 65. If I were, I could get close to 25 MPG at that speed. Are you sure?

Are you running different size wheels/tires and have had your speedometer adjusted for the size change?

1BadCadSTS
07-26-13, 05:40 AM
Luda has the 6 speed you have the 5 speed. Another major difference. Also I should of been clearer. I meant the srx v6 awd had 373 not the sts v6 awd.