ddillas

So my 1990 80 has been off the road for about a year and now that it's back the first order of business is getting the tags renewed. Here in the Portland, Oregon metro area we have to smog check our vehicles... and mine failed.

The culprit is high CO, Carbon Monoxide, or partially / un-burned fuel. During the yearlong down time I had all the injector seals replaced as well as the distributor... plus a bunch of other non ignition related items. It idles well and seems to drive fine, but does seem to knock under low RPM hard acceleration. Since it has never failed a smog check the last 20+ years I can't help but assume that something related to the recent work has changed the emissions output. Oh, and the air filter is new, so probably not the problem.

As I have absolutely no idea I was hoping someone here may have experienced a similar problem.

CRAZY_RUSSIAN

so i'm assuming that you went for a 30 min drive on a highway, you changed the oil a day before the test, you didn't have your AC on during the test, and you are running a FRESH tank of regular gas without any additives? all vac lines are in good order, no cracks or anything?

ddillas

Yes to all these questions... well the second and third time. The first time I just went cold to get a baseline. After that I did the items you mentioned. The vacuum lines were done when the other previously mentioned work was done... the brake vacuum booster was replaced along with the all the lines. As much as I hate to do it I will probably take it into a local certified facility to get it dialed in.

x19

Hi, If you have a high CO, you have to adjust fuel mixture with 3 mm allen wrench into small hole (may be you have to remove the plugged) next to fuel distributor and monitoring O2 sensor with DVOM. (Is only high CO problem?)

You will see the swinging the voltage on DVOM (your case is probably high 0.8~0.4 or stays at more than 0.6v, I hope that wasn't). Adjust to swing to 0.2~0.9 voltage (screw out or in) is just wright point and you will see the water coming out from exhaust tail pipe. Make sure,clean the spark plugs too.
Good luck. x19

ddillas

It looks like the culprit was right in front of me on my original post... the distributor. I took it to a recommenced facility with a Wagner gas analyzer system and the guy told me that after testing it he quickly discovered the timing is advanced too far, about 15 degrees (not sure how I ended up here)... hence the knocking under hard acceleration as well. Since he was/is not an Audi mechanic, but an honest one, he did not want to mess with the car so now I have to get it in to a proper Audi specialist, probably Stuttgart Autotech here in Lake Oswego, to get it dialed in properly... cha-ching.. ouch..

uEngineer

You could also talk with Dave at D&M Automotive in Beaverton. He does good work and his rates are pretty reasonable. I've owned my '88 90Q for almost a year now and had Dave install various parts and tune it back to health.

I'm having the same emissions test failure right now. Hydrocarbons are in the 1.4k range and CO is 1.5. A previous owner of this car used zip ties on most of the intake hoses (which I replaced with clamps) and I thought I solved the leaks, but there must be something leaking still.

x19

Hi, high HC meaning is unburned fuel caused by vacuum leaking in the intake system including misfiring, worn out cam robe(s), incorrect ignition timing, low compression and injector leaking etc.

And you have to correct HC problem first then CO can be adjust by 3 mm allen wrench (see my post #4 above. Good luck. x19

ddillas

Thanks for the ideas fellas.

As to the mechanic, I have been taking this to Rick at Save-On Tires in Tigard for a while now as he is an Audi/VW factory trained master mechanic (that's where the car is now)

For the other items on the punch list...

Cam = running a TechTonics 268 Hydro for ten years and has passed emissions every time with no problems.

Injectors = had all the injectors pulled and put new seals on this summer

Compression = tested good on all cylinders

Distributor = replaced about 4 months ago (I still think this may be where the problem lies)

Vacuum Hose = mechanic did a smoke test a few months back and all looked good

I (or a mechanic) will take these suggestion in hand and keep looking for the solution.

x19

Hi, did you test the spray pattern from injectors when you removed them?
this is better idea to see the spray pattern and some time aim of spray was off center and not mist enough or may be too much fuel spray etc.

Here is how to test.
Remove the intake boot on fuel distributor and injector on to plastic pan.

Remove Fuel pump Relay and by passe the power to operate fuel pump without start Engine ( Don't do this ! and any spark or include safety match)
If you bypass power correctly,you will hear buzzer sound from F/distributor and now you have to lift or push down float valve. you will see the condition of spray how they spray like the making mist or dropping fuel or etc.

Even you see the good pattern, you can clean all injector to make the full throttle condition few times and remove(clean) the dirty on float valve then put back all injector to engine.

Reset the fuel mixture by adjusting 3 mm allen wrench screw( see previous my post).

Good luck and Happy Holidays. x19