Avus_'03_S8

I had my 12V 1995 90 IM tested a couple months ago and it failed the HC and CO at idle, then I had the oil changed and put in new plugs and it failed worse! I've been running under a seasonal use waiver for the summer here in Alaska but that runs out this month so I need to get it passed for the winter.

Here's the readings:
Idle: HC Limit-220 Reading-638 (it was in the 400's the first time), CO Limit-.5% Reading-.81% RPM 729

2500RPM: HC Reading-85, CO Reading-.26% RPM 2422

Also the CO2 reading for both was just over 14% and 02 was .7% at idle and .32% at 2500.

I cleaned the ISV a few months ago since the idle use to sometimes bounce between about 500RPM and 800RPM, it's better but idle isn't always steady and some times the car shakes a tad at idle.

The car runs great except for the occasional idle varble, and is getting just over 20MPG driving around the city

What should I do next to try and get it to pass? I was thinking about speeding up the idle a bit or leaning it out, is this possible for this model or does the computer control it all? I've read of people doing this on older models but not for this one.

Plug wires, vacuum leaks, injectors, 02 sensors, cat??? What could it be.

SCarGo02

...fresh/full tank of gas, have the car warmed up to normal operating temperature...

How many miles are on the car?

Avus_'03_S8

I checked the voltage of the 02 sensors and it was cycling between .1 and .7 or .8 volts at idle for both of them if I remember correctly. Thus I was thinking thinking they're ok (and since the MPG is good). I suppose they could be getting bad though.

Car has 133k on it, I've had it for the last 8k or so and the service records that came with it didn't mention changed 02 sensors. But I don't know if the records are complete.

I'll give the cat a shakin and see what it does.

Edit: Also, on the previous IM test 2 1/2 years ago (before I bought the car) the CO had almost failed, it was at .45% or so.

4AudiQ

Smog Test
I FAILED the California Smog Test on 9/13/04.
Re-tested on 11/1/04 and PASSED.
Here is what I did:
HC at idle failed:
Max = 100
Meas = 139
I did the following 3 things to PASS:
1. Installed Fitch Fuel Catalyst @ $150.00
2. Replaced CATS with Summit Cats CTO-6806 @ $231.00
3. Changed oil - I am on the Auto Rx program,
so changed to Chevron Delo 400 15W-40.
HC at idle after fix:
Max = 100
Meas = 24

SCarGo02

133k mi. O2s are most likely shot...I'd replace them...

Avus_'03_S8

Thanks for the tips, I scored a 185 for HC at idle yesterday after changing the 02 sensors, still a little high but the oil hasn't been changed for 3k or so and the limit is 220 here in Alaska so I'm happy.

I didn't think it was the 02 sensors cause it's been getting good gas milage, I had been getting a check engine light occasionally (once every two weeks or so) back in the spring, but once I learned how to check the code it hadn't come on since until I was about to pull into the IM testing joint. The it pops on for the first time in six months, but I was ready with a paper clip this time and I got the driver side 02 sensor code 2341, changed them both out and managed to pass.

The most time changing them was spent running back and forth to the parts store, I didn't realize I'd need a slotted socket to get them in and out, oh well.

There was also a black vacuum line in the back of the engine that wasn't hooked and I couldn't find an open connection back there. There was an open one under the plastic engine cover in the back left by the air intake, so I stuck it on there, maybe that's right. I'll try and get some pictures posted later tonight to show what I'm talking about.

SCarGo02

If the O2s are throwing codes they're past due...