[Mk2] [NA] How Long does the auto choke stay on?

[P11SCL]

Ok not sure if the car is running right or not so i thought i would just check

In the cold mornings when i start the car the auto choke comes on and the car revs around the 2000rpm mark ( think thats correct for the car ) and as the car heats up the revs slowley die down to about 1200 rpm

But my question is, my car does not seem to come off auto choke and rev just below 1000rpm untill the car is full up to temp ( just under half way)

Does this seem right to you guys and gals?

Thanks in advance
Steven

[going4the1]

How long does it take for the needle to reach half-way? It should only take 3-4 miles. If it take significantly longer then you need to change your stat.

There isn't an auto-choke as such. The ECU governs the fuel mixture and uses parameters such as coolant temperature. If the stat is partially open (all the time) then the car will take longer to heat up[.

[toxo]

Idling at 2000 rpm from cold is not right. It should be 1200 when cold, 850-900 when warmed up!

[HighwayStar]

Is that just with the car standing or under load on the road? To be honest it doesn't sound that bad to me, though whether it is completely normal I don't know. Even if it is staying on a little longer it's only be for quite a short period and will only cost a fraction more in fuel. If it's a worry call an affiliate for a pro view. Don't forget start up and air temps of late may well have been very low.

R.

[P11SCL]

so if its not right what could be up with it? Could it be the coolant temp sensor?

[P11SCL]

when i first start the car when its cold and im scraping the windows it idle at 2000 rpm

[Jim Galbally]

that doesnt sound right to me.

first things first, check the tacho is actually reading right! you can take the needle off and put it back in the wrong place easily so check this isnt the case!

the isle speed is goverened by a number f things, the main two being the idle speed control valve and the base idle.

the base idle is what you mechanically set the engine to idle at when its fully up to temp, normally by adjusting the throttle backplate (which i dont thinks adjustable on an MR2 anyway). obviously if this was set to high itll idlehigh nomatter what you do

the second is the idle speed control valve, this is a device that acts as an air bypass on the throttle, effectively an ECU controlled throttle so the EWU can increase the idle speed a small amount if it wants to.

there are also other factors that affect idle RPM such as ignition timing and fueling, but their adjustments are minor.

if your car is idling too high or too low there will be fault of some kind, first things first clean the throttle body and ISCV with carb cleaner, then start investigating faults

[cantfindausername]

the cold start injector is located just under the throttle body. You could remove the connector plug (wiring not fuel line) and see how it runs. The ecu night still be trying to run it, but no extra will be injected thus reducing your idle. Worth a try.

[Jim Galbally]

increased fuel will not cause an increased idle speed (providing the current mixture is semi-sensible)