Its all going well. No, honest, it really is! But- (and I'm not sure if this should be in the electrics forum) - the idle-up vsv ain't playing ball. The valve itself is OK, I've tested it on a 12v supply and it clicks nicely, but it doesn't operate when on the car. Unfortunately, its section on the circuit diagram is one that the haynes ignored, so I wonder if anyone can answer the following:

1) What actally causes it to turn on? I can see it is bascially switched by the ECU, but what causes this to happen?

2) Which colour wire goes where - it has a black wih orange stripes, and a whitish one.... is it earthed, or is it supplied with an ign feed and the ECU earth switches it?

Ta,
James

the ecu normally switches to earth

[Edited on 11/11/03 by theconrodkid]

edited it now cos conrod changed his!!!

[Edited on 11/11/03 by JoelP]

Interestingly enough, Rob Lane posted a link in another thread (DIY FI) that is to an excellent reference to all things Toyota engine related. It's bookmarked on my browser.

I am certain that you will find the answer you are looking for here:

http://www.autoshop101.com/techarticles/technicalarticles.html

Steve Graber

It appears basically NOT to come on much in operation.

It should operate when the inputs to ECU are connected from brake light input, autobox input and A/C. (I don't have them connected)

This gives idle up when electrical load increases (brake lights) and when engine load is applied (autobox, A/C).

It should also add to the auxillary air valve when car is cold as per temp sensor. I think it mentions 15 degrees difference between air and water temps.

It should have a 12v feed and then on to ECU which then grounds it internally when required.

NOTE I just double checked, if you are going to connect the brake light inputs etc then they have Diodes in line to protect the ECU.

[Edited on 12/11/03 by Rob Lane]

[Edited on 12/11/03 by Rob Lane]

I've just looked again at your post and realised perhaps, that you are not getting cold start idle up.

Is this the case?

If so it's the auxillary air valve that provides the cold start fast idle air not the Idle up VSV.

It's a wax valve that is open when cold and slowly closes as temp increases, it should have two small bore water hoses connected from engine water rail.

Sorry if I've misread the situation.

was about to reply then read Robs 2nd message- basically yeah, that's the problem. And with a good reason- we don't have the air valve any more. Firstly, it kinda got destroyed when we removed it to see what it was (oops!) and secondly we heard of people having no end of trouble with them!

Plan of action is to see if the idle vsv (if operated manually) gives enough of a boost to idle speed. If so, I'll probably make a little temp reading circuit or something to click it off when the engine warms up. Thanks for the replies though!

I think you will find it does not introduce much air compared to the aux valve and so will not produce the revs rise you require.

The bore for the VSV is about 3 to 4mm the bore for the Aux air is 8 to 10mm.

The VSV produces about 3-400rpm rise because there is no extra fuel, the aux air with extra fuel from cold start injector produces about 1200rpm rise which diminishes rapidly at first, then slower towards end of warm up. (Both relative to normal warm 900 rpm idle)

Is the bore open on the broken aux valve and you have reduced revs with idle screw? or is it closed? Could you rig up another solenoid in its place?

[Edited on 12/11/03 by Rob Lane]

James

Found the following helpful for sorting idling problems on my MR2.

http://www.mr2mk1club.com/repairsp15.html

Cheers

Dean