finally!

Failed emissions on two areas:

Borh are from Low speed results (15 mph) test

HC (PPM):
Standard (max allowed): 152
Tested at 239

CO (%)
Standard (max allowed): 0.86
Tested at 1.24

Engine was warmed up for approx 20-30+ minutes

1989 S4, 5 speed

Will new 02 fix ?

Here are the other readings for low speed:
Nox:
Standard: 1146, tested at 225

Dilution:
Standard: >6.0, tested at 15.14

HIGH SPEED TEST RESULTS:
HC: standard: 148, tested at 148

CO%:
Standard: 0.94, tested at 0.51

Nox
Standard: 1047, tested at 133

Dilution
Standard: >6.0, tested at 14.51

Thoughts?

brutus

Move out of Texas !

Speedtoys

Ya..don't FIX the car, that'd be all wrong.

finally!

C'mon guys, need suggestions not comedians !

Lizard928

You need a new O2 sensor, and verify that Temp II sensor is in spec

joejoe

Old school trick is change the oil just before test, then you have no fuel/oil mix and should help some.

dr bob

Start with the easy stuff, like ignition maintenence that may not be quite up to date. Plugs for sure (easy and inexpensive), inspect caps and rotors, maybe wires if they are more than a lot old. HC reading is from low-speed misfire, but the CO high means there isn't an air leak. NOx reading shows it isn't lean.

Remember that tailpipe readings from after the cat may reflect the way the engine is running, but the readings are soggy'd/muddled up by the catalyst. Valid readings for real diagnosis come from the test ports/pipes in front of the cats.

A new oxy sensor is helpful past 25k miles or so on the old sensor. The sensors start to lose responsiveness as they age, so max benefit shows up in non-steady-state driving. The load during a rolling dyno test is pretty stable. So while a new sensor might help, it's not a miracle cure on a car that's already close on mixture.

finally!

Plugs approx one year old
Oil changed approx 500 miles ago
Bought new O2 sensor, will install Wednesday
Calling Roger tomorrow to see if he has Temp II sensor (anyone have the part number?)

Follow up to follow post the above

brutus

I hope it works out so you can stay in Texas ! as noted a misfire at low speed if you are running the triple electrode plugs consider using the plain old copper single ones.

WICruiser

Sounds rich, especially at low speed so the O2 sensor is a good first change. The higer speed the exhaust would be hotter so the catalyst may be able to burn off the excess fuel better (may actually indicate the cats are OK). Let us know what the new O2 sensor does to the results.

xschop

Sounds like weak spark and/or bad timing. As long as your ign parts are good and timing is correct, then you can suspect o2 sens. Any car I've ever had to smog got 5-6oz. Acetone with 10 gal. fresh petro....never fails.

Lizard928

Also check to make sure your FPR and Dampners are not leaking fuel.....

ALKada

Kenny, is your exhaust modified in any way? Are you still stock?

finally!

Installed about a year or less ago X-Pipe and HiFlow cats from roger

Passed emissions fine with them last year! Only major work since then is:
- New fuel pumps
- top end refresh (belts, etc., etc.)

finally!

Forgot on list above, recently installed from Roger a EIS intake system. New plugs about 15k miles ago along with wires

picking up from Roger today new distributor caps and rotors and Temp II sensor. Going to install them along with new O2 tomorrow. Put in some "Guaranteed to Pass" about 1/2 tank of premium ago. After get all that done will put in, as suggested here in this thread, 5-6oz of acetone or tolulene, get her good and warmed up and try again.

Have fuel pressure gauge on the passenger side fuel rail and FP shows good. Havent seen any fuel leaks anywhere.