Fast idle...again

[miniturbo]

Hi Guys
After searching it seems there is some problems with hunting and idle problems but cant find a answer to my problem.
Opon startup (cold) it idles at 2500ish until its warm and goes to around 1500 , and ive backed the idle ajuster to as far as it goes?
I thought mybe a vac leak but im showing no codes on the ecu?
Any ideas?

Cheers

[turbo11]

Idle at 2500 is pretty normal for cold start but not sure about your 1500 when its warm. Only thing i can say is that i changed my thermostat to make sure its warmed up fully. That could give you a high idle if its not fully warmed up

[pheebz]

my car is the same... my mechanic has turned down the idle as much as possible but it still idles at about 1500 or more... some times drop down to about 1 but doesnt stay like that that long.
no idea wat to do

[JohnT]

Guys

Are you sure you are doing the idle adjustment correctly? If you adjust anything other than the brass set screw towards the back of the throttle body (on top of the body) you are actually playing with the wear stop or the slow shutdown mechanism. In the info database there is an item on slow idle adjustment.

Start up idle should be around 2,000 then shopuld drop to under 1,000 on warm up. Any air leak will pull the idle up, a worn vac hose or such will cause it to fail to settle down, but often that leads to hunting. Similarly, if your idle up is jammed on (it is driven by a relay & electric air valve) then the idle will be high. To check for that see if the revs change when you turn the head lights on at idle - they should go up and you should hear the idle up relay click in - in the City that air valve is in the metal box along with the MAP sensors. If the revs don't change, there is a problem with your idle up relay being jammed on or damaged so it leaks air even when it is not turned on.

Thinking about what you describe it sounds like the idle up relay is jammed on or the idle up air valve is jammed open.
John

[James]

Their are a few possibilites, either someone has palyed with the throttles mechanical stop screw, check that the throttle is only just resting or just off this at rest, you have a vacuum leak, quite possibly through a bung vacuum advance cannister, or as John said a bung idle up valve. I will take a picture of the hose to squeeze to check you idle up valve shortly.

[miniturbo]

Thanks Guys , yeah i did think it may ahve been a vac leak but i thought a fault code would show on the ecu?Bigelboe that would be great if you could post the pic and also if you could email me the pic for the vac hose's that you ended up removing would be appreciated.
My throttle stop doesnt look as tho it has been played with and i did spray engine start over the vac lines hoping to increase revs but didnt make the revs climb, were is this idle up valve?
CHeers

[JohnT]

The idle up solenoid (air valve) is in the metal box that contains the MAP sensors - brass coloured from memory. You test if it is faulty the way I wrote up last night by turning headlights on and off, you don't need to look at it unless it is crook. It connects to the throttle body by a vac line that increases air flow to the engine to increase the revs.

No fault codes show on ECU for a leaking vacuum hose or sick idle relay, the engine has no way to tell it that you haven't just opened the throttle a bit and let more air in.
John

[miniturbo]

Thanks guys for the info.
Ive fired the car up today and turned the head lamps on after it was warm and the revs dropped by approx 200rpm, so im presuming its a faulty idle up valve as you suggested JohnT.
I have another complete black box so ill remove whats not needed in it and try that one out.Anyone have a picuture of what all the units in the box do?

Thanks again

[James]

I have removed the idle up valve and I just run a warm idle of about 1050rpm, this mean when I turn the headlights on it only drops to about 900 which is low enough in my car, it idles pretty lumpy with the port and polish and other mods.

[pheebz]

sorry to b such a noob... just wondering if any1 could take a photo of the idle adjustment screw n Idle up adjuster screw
cuz i have no fucken idea of wat they look like... cheers guys

[James]

[James]

Ignore the red, those three turny motions are the idle adjustments

[miniturbo]

ive removed all the EGR system and basicly only have the MAP sensors in there and it seems to run smoother but still idles to high, im running out of ideas now? i might just leave it how it is for now.

[James]

Can you see air between the idle stopper screw and the butterfly arm thingie?

[miniturbo]

no thats contacting against the stoper ,but when its running if i put abit of pressure on that to hold it back it almost dies and begins to hunt but thats with pressure on it.
The yellow paint is still on the stooper screw so i would presume it hasnt been played with?