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I was messing around while waiting for my food at checkers and found something out. I was turning my steering wheel back and forth and the engine seems to rev up a little during this. I just thought it was wierd, anyone else notice this. Wonder why it does this?
 

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power steering....duh....:)
 

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darnit mx u beat me to it....nicer too...oh well.
 

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LMAO...you BOTH beat me to it !!!! Dos Equis please !!!!!!
 

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Discussion Starter #6
I did not think the engine would rev under the power steering. I did not notice it on my other cars. I thought the idle speed would have been enough to power the steering.
 

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Don't argue with an insomniac.
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You guys all got therel ahead of me. Mx & the others are correct. Try to turn the steering wheel with the engine not running (but key ON) and you will see why the idle would not be enough to power the pump. This is a heavy front end, it takes a LOT of effort to turn the wheels, and if it didn't rev a bit the engine would not provide enough power to do it.
 

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Well............might be a defect. Could be the steering whatchmacallit is shorted out to the throttle thingamajig. Might be a TSB on it somewhere.
 

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Toyota has installed this on their trucks for decades now. The older mini truck had a manual pressure actuated valve that would that would bypass air and allow the engine to rev a little when the PS pump built pressure. The Tundra has an small electronic pressure valve that feeds info to the ecu... same thing, pressure builds and rpm is increased to compensate for the load.
 

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Don't argue with an insomniac.
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Toyota has installed this on their trucks for decades now. The older mini truck had a manual pressure actuated valve that would that would bypass air and allow the engine to rev a little when the PS pump built pressure. The Tundra has an small electronic pressure valve that feeds info to the ecu... same thing, pressure builds and rpm is increased to compensate for the load.
That's interesting, I thought the added load the pump put on the engine dropped the revs enough that the electronic governor would open the throttle a bit.

And. . . . It's pretty hard to beat Mx to the punch on these kind of things. I'm starting to wonder if he has a real job :D
 

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You are all right about the extra load, but it's not just RPM that is increasing... These trucks have the cylinder drop technology, IE.. It idles on 4 cylinders, but when any load increases the engine fires on all 8. Try idling the truck with the A/C on and step out to listen to the exhaust, specially if you have an aftermarket system, you can definitely here the difference..
 

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Don't argue with an insomniac.
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You are all right about the extra load, but it's not just RPM that is increasing... These trucks have the cylinder drop technology, IE.. It idles on 4 cylinders, but when any load increases the engine fires on all 8. Try idling the truck with the A/C on and step out to listen to the exhaust, specially if you have an aftermarket system, you can definitely here the difference..
Where did you read this? I haven't seen anything referring to this on the Toyota? I know Dodge and GMC have this. With variable valve and dual O/H cams you might be hearing the exhaust valves closing a bit later, or some other change in valve timing, rather than shutting down cylinders.
 

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You would ask where I read that... I can't find it now:) The sales person mentioned it to me when I bout my truck, but I can't find anything documenting that. Maybe someone on here knows for sure???? There is a very distinct sound that my truck makes when the A/C kicks on at idle, really sounds more "throaty" when the ac kicks in. I guess the VVT could cause this...
 

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Hey I'm not saying it's the case, but remember what they say about salespeople :D

I'm pretty sure this truck doesn't have cylinder deactivation.
 

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I'm with TB on this one, sounds like the salesman was trying to make a sale and talking out of his arse.
 

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Well............might be a defect. Could be the steering whatchmacallit is shorted out to the throttle thingamajig. Might be a TSB on it somewhere.
I think Toyota should release a TSB about how the low fuel light comes on when the gas tank's almost empty :D
 

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That's interesting, I thought the added load the pump put on the engine dropped the revs enough that the electronic governor would open the throttle a bit.

And. . . . It's pretty hard to beat Mx to the punch on these kind of things. I'm starting to wonder if he has a real job :D
Nope, we have a pressure sensor on the pump output that let's the ECU know the load is coming.

Sequoia and 200 Land Cruisers get variable assist. This paper in this post shows the variable assist pump, which we do not have.

http://www.tundrasolutions.com/forums/tundra/166814-tundra-power-steering-system-paper/
 

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Hey I'm not saying it's the case, but remember what they say about salespeople :D

I'm pretty sure this truck doesn't have cylinder deactivation.

I think you may be right.. I was already buying the truck when he told me all this. I did a quick search and can't seem to find anything that says Toyota does or does not have this, so I am also assuming it does not...
 

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You are all right about the extra load, but it's not just RPM that is increasing... These trucks have the cylinder drop technology, IE.. It idles on 4 cylinders, but when any load increases the engine fires on all 8. Try idling the truck with the A/C on and step out to listen to the exhaust, specially if you have an aftermarket system, you can definitely here the difference..
You were lied to. The Tundras don't have cylinder deactivation.
 
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