sjc2467

There are several diagnostic and repair methods that require holding the engine at an elevated rpm, while in neutral (park). For example, charging and pressure testing the a/c system should be done at a higher than normal idle speed (1500 is 2000 is typical). With cable-operated throttles, this is easily accomplished (for example, with a credit card or similar thickness item on the throttle stop). On many newer vehicles, I can command a higher than normal rpm with my scantool, but I don't think that is possible on my Lexus (it's a '93, so OBD1, which doesn't support bi-directional control, as far as I know).

Is there any easy way to do this with the electronic throttle on an SC400?

(Other than having an assistant press the gas pedal.)

I suppose some device could be rigged to hold the gas pedal down, but if something goes wrong, it could raise the rpm too much (an impatient neighbor used to wedge an ice scraper between the seat and the pedal to help warm up his car on cold days; one day it slipped and threw a rod from over-revving).

Thanks in advance!

2jznosht

So you need the car to idle at a certain rpm while you are under the hood correct?

sjc2467

Exactly. In this particular case, it's for checking a/c pressures. The obvious solution is to have an assistant hold the gas pedal, but perhaps there's a way to do it without an assistant..?

MMCtuner

Yes. You can take off a small cover on the passenger side, between the air filter and strut and there you can accelerate the car by hand. It's secured by three clips.

Ali SC3

iTrader: (10)

93 is not electronic, when you want to raise the rpm's under the hood, you just turn the part the throttle cable is attached to with your hand.

sjc2467

Thanks for the replies!

After glancing at alldata, earlier today, I began to suspect that it is, indeed, a mechanical throttle. I'm not really sure why I thought it was electronic (I just started driving the car, but that's no excuse...) (Perhaps newer models have electronic throttles?). Of course, this explains the need for the IAC valve and separate traction control throttle, which I was curious about (even without the CAN and LIN communication of modern cars, they certainly could have integrated traction control into an existing electronic throttle, and there's no need for the IAC).

Thanks again for the replies.

Ali SC3

iTrader: (10)

its mechanical, the vvti models moved over to a half electronic half mechanical system (basically electronic but still uses a throttle cable that goes to a sensor on the throttle body, the throttle is then controlled by a motor), and the new toyota's use full electronic there is a bunch of sensors. most any toyota pre 1998 is going to have a mechanical throttle and a seperate trac throttle if it has trac.

in summary, you can go ahead and wedge your credit card in there, it will work.