idle valve

Posted: Thu Nov 03, 2011 1:13 pm

USELESS!!! did not do a thing, its now idling at 1000 so bit of a improvement, but nothing dramatic. Wasnt sure about air leaks before but now i do as once i fitted iac i could hear a whistle from that area, not too noticable but its there. Does someone know the part number for genuine iac? So now i have 2 valves and both useles Laughing

hope this will help someone to avoid doing the same mistake as i did

Posted: Thu Nov 03, 2011 5:13 pm

i was looking at buying one of those cheep ones from ebay as every now and then ( although appears to be getting more frequent ) ill be just driving along and pull up at some light and then revs will be jumping up and down really fast between 1000 - 1300 rpm. If i turn it off and back on its fine untill the next time

the origonal isv would just make it rev constantly at 1300 when it played up so i bort a 2nd hand one and that makes the revs jump up and down.
if its running normally and you pull the connector off the isv it just goes into revs bouncing up and down mode.

maybe i have two duff ones or theres something else somewhere

either way i aint got a clue where to start

someone said to increase the engines natural idle air flow on the throttle body - but i was advised against this by the garage

they just wrekon that i have 2 duff isvs and need to buy another
tried cleaning them both but nothing think ill have to just live with it

Needs to get out more Joined: Dec 03, 2010 Posts: 178

hi luigi, have you checked for fault codes? i think its worth you doing so if you haven't as you may have another problem. i dont know for sure but if the idle valve was no good wouldn't the car be stalling aswell? when my engine is running and i unplug the idle valve my car stalls, so i guess(maybe wrongly) that the engine wont run if the valve is no good. and if you are hearing some hissing you should sort out the possible leak somewhere, did you put a jubilee clip on the hose of the valve?

Posted: Thu Nov 03, 2011 10:24 pm

This sounds like what is sometimes needed when a car's battery has gone flat, especially the V6's and 8v. Not sure how but it is said to 'synchronise' throttle potentiometer? avoids needing to use vag com to do a throttle body alignment.
Not sure if the 16v has a throttle potentiometer, did it work?

Posted: Sat Nov 05, 2011 1:54 pm

HI, no it didnt work obviously Cool

when i unplug my isv nothing happens Question

it brought revs down maybe by 300 so its down to 1000 but still not what it was before. I havent done the jubile clip yet, but thinking more about fault codes Rolling Eyes

Needs to get out more Joined: Dec 03, 2010 Posts: 178

if you have a laptop its not expensive to get an ebay lead and use vagcom to check for codes. you only need the freeware version to check for codes.

Posted: Sun Nov 06, 2011 5:49 pm

ok and whats the cable called? can you just tell me how it works? but to clear them , what do i need to do?

Needs to get out more Joined: Dec 03, 2010 Posts: 178

search ebay for vagcom kkl lead, and you will also need the vag 2+2 adapter lead on ebay aswell, then follow the instuctions and you will be able to check for fault codes and look at what readings the sensors are showing. If you get them, theres a section on the forum for vagcom (now called vcds lite)if you need help.
some people slag these leads off but from my expirience i haven't had any problems, you can buy a lead with the full version of the software from Ross-tech(do a search and see what the software is like and how to use it), i think its over £100, but just for checking codes and checking what sensors are showing you dont need the full version.
you need to seal up any leaks before you look at possible problems with other stuff.

Posted: Sun Nov 06, 2011 10:17 pm

Does the 16v have an idle air screw?
Just thinking out loud, if the new isv is not identical to the old one, it might be possible to compensate for the difference in airflow, by adjusting the idle air screw (if there is one?)

Posted: Mon Nov 07, 2011 11:23 am

im not sure mate, where would it be located? throttle body?
thanks

Posted: Mon Nov 07, 2011 7:52 pm

Yes, it would be on the throttle body, usually a brass slot headed screw that is fitted into a 'tube' shaped part of the casting

http://20v.org/throttle.htm

in the 20v link, the late 20v pic has it labelled 'idle speed adjusting screw'

Newbie Joined: Jul 12, 2010 Posts: 15

Theres no idle screw on these engines. Its done by the ECU. Been having pretty much the same problems and changed ISV, fuel metering head, throttle body, both temp switches. Checked all the hoses for leaks.
When I was changing the temp switch on the back of the head i had to remove the " S " shaped hose that comes off the bottom of the idle valve. There was a split in the seam of the hose which i only noticed when i squeezed the hose in a certain way. Bit of silicon sealer as a temporarily repair and now ticks over just under 1,000 rpm. That is good enough for me. Plus now it goes like a scalded cat. Very Happy

Posted: Tue Nov 08, 2011 10:05 pm

Shame, could have been a way forward.