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garry62be 10-01-2012 06:16 AM

idle cable tool
what type of small tool is needed to ajust the tick over on the engine? it's the small screw where the plate rests looked at it it seems like a allen key but not sure and if it is what size? any help
many thanks

BC_ZX3 10-01-2012 07:43 PM

What engine type/size do you have?

On NA Zetec models, the tickover (idle) is controlled by the PCM (Power Train Control Module) via the IACV (Idle Air Control Valve). If you think you can adjust the idle with the old carburettor style throttle plate screw butting up against the throttle body stop, you're mistaken; the PCM will compensate for any adjustment you make.

Think of the IACV as a throttle plate bypass passageway whose cross sectional area is adjustable. When the throttle plate is fully closed at idle, the PCM varies the size of the passageway to obtain the desired engine speed and monitors it based on other engine sensors. It's claimed to be more accurate than the old method.

If you are having erratic idle problems, the two most likely candidates for problems are the IACV itself or vacuum leaks after the MAF (Mass Air Flow) sensor.

garry62be 10-02-2012 04:19 AM

ok thanks for the info it's the 2l petrol model,will leave the plate alone,it's just been for a cambelt change and notw on tick over the revs drop ever so slight but dident do it before the change?

Mike_Mac 10-02-2012 06:04 AM

battery was probably disconnected so now it has to "relearn" the idle, ect.

garry62be 10-02-2012 08:46 AM

oh ok thanks for that,i will run it a while and see again thanks

sailor 10-02-2012 11:23 AM

FYI, on modern fuel injected vehicles the throttle stop screw serves two functions.

1. it prevents the throttle plate from closing completely, which would cause wear as it hits the sides of the bore as well as tending to stick in the closed position. ('stiction" happens anyways from accumulation of "crud" over time - when it gets sticky clean it)

2. factory settings allow a specific air flow when the throttle is closed (set on a flow bench) to get throttle closed air flow in a range where the IAC system has the range to adjust it to desired levels. (needs to be able to both throttle it down when warm, and raise it for cold starting or extra loads like A/C or high alternator draw)

"Close enough to work" can be achieved through experimentation, but it's a LOT easier just to leave it alone unless damage/wear requires adjustment.


Gobliz 10-02-2012 12:57 PM

don't mean to hijack this thread but thsi guy seems knowledgeable. What can you tell me about the IACV and the whole "relearning" thing?

sailor 10-02-2012 01:55 PM

Well, in general the 'relearning" process is fairly rapid - but it can take some time & 'drive cycles" B4 the system completes ALL of it's self checks. That's why you can't disconnect the battery to clear a code before taking it in for an annual inspection - It'll show 'not ready" until it has time to check all it's functions.

Any idle speed variations in the mean time should be minor, major variations would point to some other issue like a sticky IAC or a vacuum leak for example as mentioned by BC.

If you're experiencing some problems with yours Gobliz, start a thread giving the details & the members here will take a few guesses as to what might be the issue & where to start checking for trouble....

Gobliz 10-02-2012 01:57 PM

Did that. can't afford anything, but I didn't let it relearn last time I modded. I'm gunna do that next weekend along with "the big 3"

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