re. CIS-E 3 problems continued...frustrated.

[Ben Swann]

Eric,

Have you made sure that the seal for the throttle body Idle adjustment screw is in good condition and is turned all the way in.  If this is passing any air, it can/will cause an idle bounce?  

Also,  are you absolutely sure the idle switch is closing consistantly?

I encountered similar problems when I was sorting out my ELGIN 270 Cammed  heavy breathing 2.3 NG from 87.5GTC now installed in '87 4kq (Project GTQ).  Along with the initial rough idle, I had a problem getting the idle to stablize.  I installed/re-adjusted several sets of switches and swapped throttle bodys a couple of times until getting everything tight and functioning properly and consistantly.  Once you get the idle switch closing consistantly and no air passage through the throttle body (idle bleed screw or throttle plate not closing properly, etc.) and  the ISV if not defective - will then work as advertised and raise and lower the idle.  Again the Throttle screw needs to be fully closed for the system to operate properly - if you find you need to back it out to keep the engine running, then the ISV circuitry is not kicking in properly.  

Also, ignition timing will tend to wander if not set right - I have not figured out exactly the trick, but got mine dialed in by trial and error.  If your engine is stock, then getting these adjustments dialed in should be all the easier.   The system also tries to adjust the ignition timing for you to keep the idle in range which can drive one crazy if something else is not working.

I was able to get the engine to smooth out at idle by advancing the cam timing, but did lose a little top end, but it still pulls hard and fast to the redline.   I found that the high lift and duration cam did not agree well with getting the NG to idle well, but with adjustable cam sprocket, I can advance cam 4deg. for reasonably good idle, or retard cam  4deg. for great mid-top end. Need to re-adjust ign. timing when you do this to compensate.

Ben


[Date: Sun, 13 Feb 2005 15:27:46 -0700 (MST)
From: "Eric S" <scirocco at vintagewatercooleds.com>
Subject: CIS-E 3 problems continued...frustrated.
To: quattro at audifans.com
Message-ID:
<1465.192.168.1.233.1108333666.squirrel at www.vintagewatercooleds.com>
Content-Type: text/plain;charset=iso-8859-1


Symptoms:

Poor cold start (very low idle)
Once warm, idle gets too high and ISV keeps it from going over 1100 rpm
(bounces).
Codes being thrown: Air flow meter and Full throttle switch shorted/open.

What I have done:

Noted that full throttle switch works perfectly in open loop mode (warm
up), once up to temp, it is ineffectual (does not change DPR current/bog
the engine with too much fuel like during warm up).

Unplug the idle/full throttle switch once warmed up, idle goes up to a
steady 1400 rpm.

Replaced Air flow meter with known good tested unit...no change.

My questions:

I am really confused that during open loop mode the car properly responds
to the full throttle switch, then when in closed loop ignores it and
throws a code.

Air flow meter...what could cause the computer to think its signal is bad?

I suppose the bentley would be more revealing, as I could check resistance
of the pins at the ECU...but that whole full throttle switch thing has
gotten me thinking that its very possible all wires are good, that its the
ECU at fault here.

What all do you guys think?  Any further troubleshooting suggestions?

New parts so far (related to injection anyway):
air flow meter unit
ISV
O2
Coolant temp sensor
Full throttle switch

This system has re-affirmed my hatred for CIS-E in general...would
appreciate any help here.

-- 
Eric
www.vintagewatercooleds.com

1981 Scirocco S (TDI swap project)
1988 Audi 90 Quattro
1990 Corrado TDI
1991 Cabriolet (2.0 crossflow 8v project)]