High Revs

[takum]

hi all hope somebody can help me with my problem I have a toyota carina 2.0 litre 1987 when I start the engine from cold the engine goes to 2100 rpm I think they have gone gradually up, when the engine dies down to about 600 rpm the runs really smooth.thanks i know that the the revs do get higher when cold because of the choke or whatever it is nowadays,but is it a bit excessive at that range , John.

[Raistlin]

In lieu of a choke plate, most computer-controlled cars use a secondary air channel controlled by the idle air control valve.

The IAC circuit is like a carefully controlled air leak, and the IAC valve determines how big a leak it is.

When you turn the ignition key to the "On" position, the computer takes a reading from its coolant temperature sensor.

The lower that reading, the more it closes the IAC valve to restrict airflow.

From there, the computer can take a few actions: It can advance timing to increase engine rpm, it can inject extra fuel to enrich the mixture or it can adjust engine rpm by simply balancing fuel injection with airflow through the IAC circuit.

Once the computer has stabilized engine rpm, it'll wait until the engine gets up to operating temperature before returning the idle to something more civilized.

[takum]

thanks for that Raistlin I am not much up on that set up but sounds ok to me what you say . Does the revs seem high to you I have had the carina about 7 years now and still love it but it seems the revs have got higher than they were.is there any adjustment needed I wondered if there was an air pipe split or something but i have checked. what I can. I do to slow it down a little, many thanks for your reply John.

[Konrad C]

This is a question that pops up about high idle speed when cold.

If you drive the car straight away, the engine warms up faster, which in turn brings the idle speed down, saving your fuel.

My car has an high idle speed first thing and it down within a mile or two. Like your engine my car settles down close to 600rpm, unless I am using the aircon, heater or anything with a high current draw.

There is not much you can do, and I would not worry about it.

Konrad

[takum]

thanks for that Konrad 1800 revs when started seems a bit high just wondered weather there was an air leak or a valve sticking somewhere like you say I also drive it away as soon as it s started I have a feeling it has never been always like this seems to have built up gradual but might be imagining it lol

[Daz1978]

I had this problem after I had bought my carina happened out of the blue then got gradually worse, as Raistlin says its air leak related. Find the trottle body and underneath it you should see a green or black block with a connector and hose attached.

This is the idle air control valve either its faulty / gummed up or like mine it was faulty and the vacum hose feeding it had a tiny hole in it, had to replace both to sort problem, 6 years later now and issue hasn't resurfaced so id say its fixed!