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Scott
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..
Cheers
Scott

Customer:

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

Scott and 4 other Car Specialists are ready to help you

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..
Cheers
Scott

Scott and 4 other Car Specialists are ready to help you