1990 Audi CQ Running Rich

[ufoforever]

Hi, I'm new to this forum. I have a 1990 CQ and I have been experiencing problems. I have a code 2341. The car was running great, then one day it went into limp-mode. Found out the fuel pressure supply line was leaking, so I fixed it. The car started running awful, so I did a tuneup, replaced the cap and rotor, all new spark plugs, and a new bosch fuel filter. Still had an issue, so I traced it to a bad fuel injector. Next I replaced all the injectors with the 034 motorsports fuel injector upgrade. Following that I still had a CEL. So now, I am stuck. I still get a 2341 code (translated to 02 sensor control limit exceeded). I experience slightly longer starting time, somewhat fuel odor, and limp-home mode. The fuel pressure gauge I installed recently shows a residual 40psi which eventually drops to zero. At idle the pressure is 43-44 with vacuum, and without vacuum the pressure goes at most 54-55psi. Does anyone have any ideas? I am automotive graduate, but brand new to Audi, let alone the rare 90' CQ.

[x19]

Originally Posted by ufoforever

Hi, I'm new to this forum. I have a 1990 CQ and I have been experiencing problems. I have a code 2341.

The car was running great, then one day it went into limp-mode. Found out the fuel pressure supply line was leaking, so I fixed it. The car started running awful, so I did a tuneup, replaced the cap and rotor, all new spark plugs, and a new bosch fuel filter. Still had an issue, so I traced it to a bad fuel injector. Next I replaced all the injectors with the 034 motorsports fuel injector upgrade. Following that I still had a CEL.

So now, I am stuck. I still get a 2341 code (translated to 02 sensor control limit exceeded). I experience slightly longer starting time, somewhat fuel odor, and limp-home mode. The fuel pressure gauge I installed recently shows a residual 40psi which eventually drops to zero. At idle the pressure is 43-44 with vacuum, and without vacuum the pressure goes at most 54-55psi.

Does anyone have any ideas? I am automotive graduate, but brand new to Audi, let alone the rare 90' CQ.

I am wondering that did you fix your problem ? or adjust CO mixture? or other thing ? x19

[ufoforever]

I haven't narrowed the problem further, although I am burning rich, oil smells like rich mixture. I did replace the rear coolant sensor on the firewall side of the motor, and that helped much, but the problem persists.

[Solid20vq]

Originally Posted by ufoforever

I haven't narrowed the problem further, although I am burning rich, oil smells like rich mixture. I did replace the rear coolant sensor on the firewall side of the motor, and that helped much, but the problem persists.

When I first got my 90quattro 20v I had very long crank times and power issues. The Audi tech diagnosed it as a bad fuel pressure regulator, which was causing a mixture so rich it destroyed the O2 sensor. I had to source the part from a 200. I can provide the PN if it sounds like something you'll need.

[x19]

Originally Posted by ufoforever

I haven't narrowed the problem further, although I am burning rich, oil smells like rich mixture. I did replace the rear coolant sensor on the firewall side of the motor, and that helped much, but the problem persists.

Code 2341,
Probably, you have to look the operation of 02 sensor when you could start engine, Here is how to probe the 02 and hook up either teat wire of DVM to 02 wiring to( insert wire between or connection on 02 wiring = Green and black wire) and other test wire of DVM goes to chassis ground with setting DC Volt scale. You will see the voltage and should see 0.2 ~ 0,8V fluctuated with idling even engine raised high RPM. if you see the voltage that I listed, furl mixture is OK. Out of CO adjustment makes hard to start too. x19