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Scott, Automotive Engineer
Category: Car
Satisfied Customers: 251
Experience:  30 yrs experience with Aussie, Japanese & British cars, fully qualified..
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Toyota Town Ace: Hi there.I am an owner of a Toyota Town ace

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Hi there.I am an owner of a Toyota Town ace 2001 mod with KR 42 engine.The story is...The idle on neutral was low so i played up with the idle screw on the throttle body for a while.Couple hours later the idle was really high and i cant find the exact spot where the idle it use to be.How can i find the correct rpm in my car when on idle?I have to say that is an EFI engine.I have clean the throttle body and PCV valve and i have no vacuum leaks. 

Scott :

Hi there..
There's an IAC (idle air control)device that is plumbed to take air from before the throttle body & circuit it to the intake manifold after the throttle body. That's what is used to vary idle speed to compensate for a cold engine (fast idle). It is controlled by the ECU. The IAC can have a tendency to be erratic if choked with carbon etc. It may pay to have a close look at the electrical connector thereof as well..
I hope this helps.. Once the IAC is functioning correctly you should be able to tune the base idle with the throttle body screw..


Ok, but what is the OEM rpm when on idle for my car.I need to know that to make this right.

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The base idle speed (with engine fully warmed up) is 700 to 750 RPM. With relatively high K engines & in cold areas you may need a little more for a stable idle. Ultimately anything under about 900rpm will be acceptable. If it wont idle under this, there's other issues. This assumes it's a manual transmission..

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