K jet auxilary air valve

ChrisG · 22-02-12, 02:21 PM

Following on from a Club Audi forum question, and a query I now have can anybody help please ?

1985 80 Sport.
Starts OK
Runs OK
ticks over at about 1100+ revs at cold .
thoroughly warmed up, ticks over at ...... 1100+ revs.

12v reaching the auxilary air valve;
Engine almost cold ( started engine just to get uphill outside of the garage).

Removed the valve, not difficult but very fiddly with all the hoses in the area. Very small area showing light through the valve.
I've soaked/shaken in carb cleaner.
Valve been in freezer for two hours and there is now a lot of daylight showing.

Question please:-
when warm should there be any daylight at all through the valve?
There doesn't seem to be 12v at the valve plug connector with the engine not running ( and I have various hoses off including the connector between the airflow sensor plate and the throttle body - so running the engine without complete re assemby is not an easy option ! ).
So can I recheck the valve by applying 12v to it and if so do you happen to know which is the live feed wire colour?

Thanks.

4v6 · 22-02-12, 02:37 PM

It should close off when warm.

Run the engine until its warm and squeeze one or both of the hoses that run to the aux air valve.
If the revs dont alter then that indicates its working correctly, if the revs go down then its not.
All youre doing by squeezing the pipes is cutting off the air being bled past the throttle body, effectively mimicking the aux air valve operation.

hope that helps a bit.

TeXerv · 22-02-12, 03:04 PM

The engine meister is right. And the cable feeds the heater inside the valve. After a while the valve should close off. Proceed as the meister told you to check the valve. Is it open at warmed up engine, it seems to be worn.

ChrisG · 22-02-12, 03:11 PM

That helps a lot !
Thanks.
I suppose if it's not working properly then I shall need to replace.
KMI in Letchworth seem to do spares/rebuilds ... I wonder what cost ?
As the 'Meister 'is it possible/worthwhile to flow the throttle body on these engines and if so what might I get out of it ? I bit more power and better pickup?

I think I'm going to reassemble, then recheck carefully.
Thanks

4v6 · 22-02-12, 03:47 PM

Hi Chris, yeah the trottle body can be checked, is it the double flapped version?
If so i have one here i can do and see what happens with it.

Unless its restrictive at wide open position (can crunch the airflow numbers for max cfms at full throttle and see that way also) then i dont think youll see anything extra by changing it for a bigger one to be honest- you might well lose some driveability by going to a bigger one though.

ChrisG · 22-02-12, 05:19 PM

I don't wish to loose drivability, may not have bothered when it was new but it's different now! It's not driven as a screamer

I suppose I was just hopeful that another 5-6bhp would magically arrive

Anyway back to this afternoons little project.
It's all back together and running, very smoothly. The cold idle is about, roughly, 50-100 revs slower about 1000 -1050 instead of 1100+.
Manual says 900-1000 and this one always used to be 850-900 range.

I did try sqeezing the pipe, didn't seem to make a difference however by then back was aching, light fading so

a bit more work needed. No light in this particular garage so it's been left for the time being..... and its raining now....

BIGGYIN · 22-02-12, 07:40 PM

Temperature sender,maybe?
My idle on KV engine,was running high.(1000-1100)
Changed temp sender(for isv) and Bob's your Uncle.Idle dropped,to 850.

22-02-12, 07:40 PM	#7
BIGGYIN 4 ring whore! Classic Audi Club Member Join Date: Mar 2009 Location: Merseyside Posts: 7,976	Could be/might help Temperature sender,maybe? My idle on KV engine,was running high.(1000-1100) Changed temp sender(for isv) and Bob's your Uncle.Idle dropped,to 850. __________________ q90 B2 Type 85 - q90 B2 Type 85-PROJECT-ABY 20vt KARL. Injection is nice but I'd rather be blown

22-02-12, 02:37 PM	#2
4v6 Ex Member Classic Audi Club Member Join Date: Dec 2007 Posts: 5,565	It should close off when warm. Run the engine until its warm and squeeze one or both of the hoses that run to the aux air valve. If the revs dont alter then that indicates its working correctly, if the revs go down then its not. All youre doing by squeezing the pipes is cutting off the air being bled past the throttle body, effectively mimicking the aux air valve operation. hope that helps a bit.

22-02-12, 03:04 PM	#3
TeXerv Grown up member Join Date: Oct 2011 Location: Northern Krautland Posts: 241	The engine meister is right. And the cable feeds the heater inside the valve. After a while the valve should close off. Proceed as the meister told you to check the valve. Is it open at warmed up engine, it seems to be worn.

22-02-12, 03:11 PM	#4
ChrisG Senior Member Classic Audi Club Member Join Date: Dec 2007 Location: Bracknell, Berks. Posts: 1,465	That helps a lot ! Thanks. I suppose if it's not working properly then I shall need to replace. KMI in Letchworth seem to do spares/rebuilds ... I wonder what cost ? As the 'Meister 'is it possible/worthwhile to flow the throttle body on these engines and if so what might I get out of it ? I bit more power and better pickup? I think I'm going to reassemble, then recheck carefully. Thanks

22-02-12, 03:47 PM	#5
4v6 Ex Member Classic Audi Club Member Join Date: Dec 2007 Posts: 5,565	Hi Chris, yeah the trottle body can be checked, is it the double flapped version? If so i have one here i can do and see what happens with it. Unless its restrictive at wide open position (can crunch the airflow numbers for max cfms at full throttle and see that way also) then i dont think youll see anything extra by changing it for a bigger one to be honest- you might well lose some driveability by going to a bigger one though.

22-02-12, 05:19 PM	#6
ChrisG Senior Member Classic Audi Club Member Join Date: Dec 2007 Location: Bracknell, Berks. Posts: 1,465	I don't wish to loose drivability, may not have bothered when it was new but it's different now! It's not driven as a screamer I suppose I was just hopeful that another 5-6bhp would magically arrive Anyway back to this afternoons little project. It's all back together and running, very smoothly. The cold idle is about, roughly, 50-100 revs slower about 1000 -1050 instead of 1100+. Manual says 900-1000 and this one always used to be 850-900 range. I did try sqeezing the pipe, didn't seem to make a difference however by then back was aching, light fading so a bit more work needed. No light in this particular garage so it's been left for the time being..... and its raining now....