Code I've never encountered before...

Sat Apr 19 03:33:42 PDT 2008

Very interesting, Cody. Mine does that also...... QLCC'd 1987 5ktq throws a 
brief CEL when I move the throttle forward. It only happens after the 
engine warms up, maybe 8-10 minutes into the drive. But it stays sensitive 
to throttle advances until I shut the engine down. I haven't been able to 
locate any cracked or leaking vacuum hoses.

I swapped in a stock ECU to see if it was being caused by the QLCC chip, 
but the touchy CEL was the same with both ECU's.

Subsequently, I drive the car very gently, and have discovered that I CAN 
sometimes get very limited throttle advance without the CEL if I control 
the pedal pressure at "egg shell" levels.

Have given up trying to find the open line, and only drive the car locally 
a few times a week as a second car.

Speculation#1: It is a leaking wastegate diaphragm (but haven't taken the 
wastegate apart to check that out.) I'm driving on the original wastegate 
diaphragm, so it is VERY old.

Speculation #2: It is a vacuum leak somewhere in the foot-long + rubber 
emissions hose that starts from the lower driver-side of the block and goes 
vertical past the sparkers and connects on top of the valve cover with 
those half- dozen other vacuum hoses associated with the turbo system and 
idle control.

This started about a year ago, and the codes were the same ones you 
describe. I asked my very experienced Audi mechanic and his 2 man staff for 
help and they found one small vacuum line open....and fixed it......and the 
CEL light came on less frequently.....but it wasn't back to "no CEL."

Hope you solve the mystery and tell me about how you did it.

Doyt Echelberger
Ohio  USA

 >>>>>>>>>>>>>>>>>
At 07:48 PM 4/17/2008, you wrote:
>Patient is my white '87 5ktq w/ QLCC + fuel pump relay wired to run 
>constant and boost at 1.1bar. Seems it got really pissed off at me tonight 
>driving home from CiCi's. First I noticed the fuel pump intermittently 
>getting loud, then going back to normal (1/4 tank of fuel). No 
>driveability issues at this point. Was cruising along behind a slow moving 
>vehicle at about 3,000rpm and the CEL popped on. I moved the throttle a 
>bit and it went out, put the throttle to about the same position and after 
>a second the CEL came back. Went to 5th gear and low revs and it stayed 
>out. Right before entering my driveway I checked again, 3rd gear 3000rpm 
>about 50% throttle CEL comes back on.
>
>Codes read out as 2221 and 2142. 2221 says "Vacuum hose to control unit 
>sensor - Vacuum hose leaking, disconnected, or plugged". 2142 is a knock 
>sensor open circuit code. The 2142 I've pulled out of this car before, but 
>that 2221 I've never seen before on any of the 7 5ktq's I've owned. The 
>vacuum hose looks ok to a quick visual inspection, and I've got a smoke 
>machine at work I plan to check it with tomorrow (and check for debris on 
>the fuel pump screen).
>
>Any insight or BTDT's?
>
>-Cody Forbes
>http://www.5000tq.com
>'87 5ktq - Fast.
>'87 5ktq QLCC'd plus some
>'86 5ktqCD
>'86 5k
>'86 5k
>_______________________________________________
>quattro mailing list
>quattro at audifans.com
>http://www.audifans.com/mailman/listinfo/quattro
>---
>Watch this space for ads :)