Idle Screw - 9A

[tentonhammer 10]

Can anyone confirm if the 9A has an idle screw on the throttle body? Can't see one on schematics anywhere

 

Cheers,

 

C 16V 2.0 9A

[aide 0]

from hazy memory i dont think so, idle is controlled by the potentiometer/ ecu and ISV.

[tentonhammer 10]

hmm that's what I thought, needed to be sure.

 

My C's started idling funny, when it gets warm idle starts to bounce from 800 RPM - 1200 RPM in a rhythmical fashion. If I pinch angled ISV hose (#051133997A or see circled in pic) I can achieve a perfect steady idle at 1000RPM. Hose looks fine but I think I'll swap it anyway, jubilee clip is also nice and tight.

 

[ATTACH=CONFIG]69808[/ATTACH]

 

All other vac seals (or the ones I can get to) look fine. Throttle body + inlet manifold recently been cleaned with carb cleaner. ISV not so sure about... although it was working fine before i rebuilt ignition (new distributor, cap + arm, HT leads, ignition module, ignition coil, new battery, new plugs etc). Checked all fuses. ok. Haven't checked the throttle body potentiometer yet...

 

Ideas?

[aide 0]

kjet based systems are nearly impossible to diagnose remotely, but if its only hunting when warm that at least narrows the search. there's a great book available called 'how to diagnose and modify bosch fuel injection systems' its well worth a purchase, i'll see if i can find my copy tonight and look up the symptoms.

[seanl82 23]

I had this on my KR so dont know if it will make a difference with yours being a 9a, but mine turned out to be where Id fiddled a little with the throttle damper. A turn forward and locked in place sorted it

[tentonhammer 10]

kjet based systems are nearly impossible to diagnose remotely, but if its only hunting when warm that at least narrows the search. there's a great book available called 'how to diagnose and modify bosch fuel injection systems' its well worth a purchase, i'll see if i can find my copy tonight and look up the symptoms.

 

Thanks Aide will def get my hands on something like this for the future. Found this too which could be useful:

 

http://www.amazon.co.uk/Injection-Management-Technical-including-modifying/dp/0837603005

 

I've got a feeling fueling could be an issue as it intermittently misfires sometimes whilst driving, not by much but enough for me to notice ;) Considering new fuel injectors + seals etc as the the injectors look like they've never been changed and the car is 20 years old so needs doing really! Fuel pump primes on start up but again this looks as old as the car so might replace this as well. Would love to do fuel lines too but this only increases costs further...

 

mine turned out to be where Id fiddled a little with the throttle damper

 

Sean re throttle damper - Do you mean the the adjustable nut and bolt that sits on top of the throttle body? See circled in pic

 

[ATTACH=CONFIG]69812[/ATTACH]

 

TO CONFIRM - Circled in pic above is in fact the Idle Screw (16V 2.0 9A)

Edited October 22, 2012 by tentonhammer

[aide 0]

i have my book here but can't find the hunting symptom, i'll scan the whole chapter!

 

that book looks like its the equivalent alright.

 

that screw adjusts airflow by adjusting the throttle butterfly plates, i doubt it will solve a hunting issue.

[tentonhammer 10]

Thanks appreciate you scanning the book for me! Gotta be in there somewhere ;)

 

Funny what you were saying about airflow because it definitely sounds like there's too much air in the system. When I squeeze the angled hose attached to ISV (circled in previous post) I reduce the amount of air into the ISV unit allowing me to correct the idle sorting the problem. This was originally why I was hoping for some type of idle screw (like on the KR) so I could calm things down a little.

[aide 0]

pm an email addy, i can't upload this scan for some reason.

[tentonhammer 10]

PM Sent

 

Nice one

[seanl82 23]

Alright mate, sorry for late reply. I'm not sure if thats it, its hard to make out in the photo and I cant remember tbh. Its basically a damper with a rubber boot. When the throttle returns to idle on the tb, instead of snapping shut, it hits the damper and closes to idle gently. It was underneath towards the back of the tb iirc. It had the locking bolts that I can see on your pic though, and it was set too low iirc. A turn outwards sorted it.As said above, I think I inadvertantly turned it (or was just curious and fiddled!) when I took the tb off to clean it. You may have nudged it when cleaning I suppose. Hope this helps mate.

[tentonhammer 10]

2 x Faults found

 

Diagnosis here: http://the-corrado.net/showthread.php?77161-Idle-Stabilizing-Valve-%28ISV%29-Testing&p=933075#post933075

 

Misfiring ceased.