Lexus082

My warm engine idle speed is around 200 rpms or so. Its so low that the car starts to shake. I have swapped throttle bodies, cleaned the throttle body, swapped MAF sensors, cleaned IACV and still have a very low idle. Car hasn't stalled out, just very low idle speed. Any thoughts?

mobilyte

iTrader: (3)

i'm surprised the engine isnt stalling at 200 rpm...adjust the throttle position sensor.

PureDrifter

iTrader: (10)

have u adjusted the TPS >.>
www.lexls.com has a method for adjusting idle speed.

Och

iTrader: (3)

Well, you can try the following - theres a hose going from a nip on your intake down to the valve on your power steering pump, and theres another hose coming from the power steering pump valve and going into your intake manifold. That valve is notorious for failing and what you wanna do is bypass it. In order to do that, you have to disconnect the first hose from the nip on your intake, and disconnect the second hose from you intake manifold, and cap them both off. Then get a piece of hose (I believe its 1/4 inside diameter, or maybe 3/16), and run it from the nip on your intake straight into the intake manifold. If that solves your problem, you can replace the valve on the power steering valve, and reconnect everything as it was, but it's not really necessary, there isn't any noticeable negative effect if you permanently bypass that valve.

Lexus082

I haven't touched the tps yet. I'm afraid if I move it then it won't be "calibrated" anymore. Or is it ok if I adjust it to increase the idle? Just kinda confused that if it requires testing the resistance for correct calibration then wouldn't you mess that up by rotating the tps to adjust the idle?

Lexus082

I will definitely try bypassing the idle up valve for the power steering to see if that makes any difference. Thanks for both tips, if anyone else has anything to try I would appreciate the advice. Seems to be a difficult problem so far.

Is a low idle speed a common issue with the idle-up valve failing?

Och

iTrader: (3)

In your original post you're saying you've replaced the TPS? In any case, I don't think calibrating the TPS is that critical, its mostly to adjust the idle speed, and it doesn't adjust as low as 200rpm.

Och

iTrader: (3)

Yep, there are a few threads on this issue on these forums.

Lexus082

Correct me if this is wrong, but isn't this just allowing more air into the engine, by bypassing this valve, thus creating a higher idle speed?. Isn't this valve usually closed and then during an extra load from the power steering then open up this valve allowing more air to the engine to increase the rpms, hence idle up valve? Unless I'm thinking backwards. I just don't see how that if you bypass it and then your idle speed returns to normal that means the idle up valve is bad.

I do have my normal idle speed back which is really nice, it idles around 650 in park and then about 400 in gear.

Och

iTrader: (3)

I think the valve is open at idle, and closes as you get up to speed to make steering tighter.

Lexus082

Well I drove it some more tonight. The idle speed seems to still be alot better than it was before. Although at times the idle (in park) drops down to 500 or so and I notice a slight shaking going on. Maybe the tps needs to be adjusted also now.

My main question now is since I have bypassed this idle-up valve and the idle speed has gotten better does this mean the idle-up valve is bad? I didn't notice any white smoke or p.s. fluid in the intake? Thanks for the great help Och, I really appreciate your time & effort.

phy

I got the same problem. Really sux, 400 in gear and 600 in park. Let me know how it goes. I heard it's a ECU problem tho.

Lexus082

I read some more on this topic and it seems to me that the only time this idle-up valve opens is when the steering wheel is turned all the way either to the left or right.

Which means that bypassing this valve and connecting a hose directly from the intake to the manifold is going to allow more air into the engine which in turn is going to raise the idle speed. I'm not sure if someone miss read this (from the other posts I have read), but Toyota states "the system (idle-up valve) is only functional during very low speed maneuvering or at idle"

It further states the idle up valve only opens when the power steering pressure exceeds the calibration point of the control valve... and then it says: because the power steering pressure only exceeds the calibration point of the valve when the steering wheel is turned to its stop. (All the way to the right or all the way to the left.)

So bypassing this valve and connecting a hose directly from the intake to the manifold is just going to increase the idle speed. And just b/c the idle increased doesn't mean the the idle-up valve is faulty... So my low idle issue remains unsolved.

Broker404

why is this a bad thing? mine does this and I see no problem. engine runs very smoothly

PureDrifter

iTrader: (10)

meh, motor is supposed to run between 600-650 idle. just adjust ur TPS and be done with it...