failed smog today. Troubleshooting with helms manual and basic tune-up stuff. Tech @ shop said I could try running the engine real hard for 20 mins (which i did not do b4) and/or try replacing O2 sensor. LOOKING for some good advice and/or cheats to get it passed. Would prefer remedy.

94 LS B18B1

MODS: 1 step colder ngk plugs w/ ngk wires, 3" CAI, dc 4-1 header w/ (passed previously with same mods except header)

STATE: CALIFORNIA

Failed 15MPH

15 mph CO2%: 14.03, O2%: 0.31, HC:max90 ave21 meas125, CO%:max0.54 ave0.06
meas0.74, NO:max711 ave150 meas1226 FAILED

25 mph CO2%: 14.40, O2%: 0.00, HC:max56 ave13 meas55, CO%:max0.53 ave0.05 meas0.35, NO:max754 ave136 meas0309 PASS

 

anyone? looking @ the NOX numbers, and the reading i been doing maybe i need a new cat? im clueless.. please help

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Medek &raquo;</TD></TR><TR><TD CLASS="quote">failed smog today. Troubleshooting with helms manual and basic tune-up stuff. Tech @ shop said I could try running the engine real hard for 20 mins (which i did not do b4) and/or try replacing O2 sensor. LOOKING for some good advice and/or cheats to get it passed. Would prefer remedy.

94 LS B18B1

MODS: 1 step colder ngk plugs w/ ngk wires, 3" CAI, dc 4-1 header w/ (passed previously with same mods except header)

STATE: CALIFORNIA

Failed 15MPH

15 mph CO2%: 14.03, O2%: 0.31, HC:max90 ave21 meas125, CO%:max0.54 ave0.06
meas0.74, NO:max711 ave150 meas1226 FAILED

25 mph CO2%: 14.40, O2%: 0.00, HC:max56 ave13 meas55, CO%:max0.53 ave0.05 meas0.35, NO:max754 ave136 meas0309 PASS </TD></TR></TABLE>

Is this the original cat? mileage on the engine? last time you replaced the O2 sensor? Cleaned the throttle bottle yet? is the timing at the stock setting? use the stock plugs instead of the 1 step colder plugs.

 

^^ like Lord Helmet said above, try using the stock plugs instead of the 1 step colder plugs?

 

owned the car for 4 years. never replaced cat or O2 sensor (treated O2 like a baby when installing dc header) 162,000 miles, throttle body, iacv, fitv, were all cleaned up very nicely when troubleshooting a surging idle problem. Idles at 800cold 1000 warm. Timeing supposed to be stock. But I had the belts, seals, and pumps changed 10k ago.

I did have a sticking throttle-cable recently but i fixed that. O2 sensor passed emissions as working, but the tech said it could be "lazy, and on it's way out" I havnt thrown any codes or a check light.. so im leaning more torwards a bad cat.

CAN someone decipher the actual reading for me and tell me if im rich, lean, or what I should be looking into.

Also considering using a product like "blue sky" for the re-test.

PS I also passed previously with 1 step colder NGK plugs. And passed the time before that with almost worn stock plugs.

Thanks for your imput

 

bump..

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Medek &raquo;</TD></TR><TR><TD CLASS="quote">problem. [B]Idles at 800cold 1000 warm[/B
</TD></TR></TABLE>

That's one of your problems right there, it's idling too high for the stock specs of 750 +/- 50 rpms at normal temp.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Medek &raquo;</TD></TR><TR><TD CLASS="quote">owned the car for 4 years. never replaced cat or O2 sensor (treated O2 like a baby when installing dc header) 162,000 miles
</TD></TR></TABLE>

162,000 miles? waaaayy overdue to for a cat replacement. You're suppose to replace them around the 100,000 miles range and O2 sensor around the 60,000 miles range. The 02 sensor is a key component because it tells the ECU if the engine is running too lean or too rich and the ECU adjust according to the signal it gets from the 02 sensors. replace the cat and 02 sensor at the same time.

I'm looking at the # and the HC measurements are high for the 15 mph range and the NOX #'s are sky high also.

HC is the hydrocarbon (unburnt fuel) that isn't burn completely by the engine.

Nox is the (Nitro Oxide SP?) if this NOX is high, it's because you're either running very lean or the timing is way too advanced causing a high temperture condition hence the high NOX #'s

Make sure the ignition and camshaft timing are exactly at factory specs and the idle is within factorys specs too.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Medek &raquo;</TD></TR><TR><TD CLASS="quote">I did have a sticking throttle-cable recently but i fixed that. O2 sensor passed emissions as working, but the tech said it could be "lazy, and on it's way out" I havnt thrown any codes or a check light.. so im leaning more torwards a bad cat.

</TD></TR></TABLE>

See the tech knows what he's talking about , replace the cat, 02 sensor, check the timing, and replace the PCV (Positive Crankcase Valve) while you're at it.

 

Now that was a great write-up, thank you very much.

I replaced the Cat today (carsound) and gave myself a tune up. I went with Iridium plugs. Im on the hunt for a ngk o2 sensor localy. re-checking the dile tomorrow to verify.

As far as timeing is concerned, I had a shop replace the belts, seals, pumps, and the valve cover gasket. I do have a helms and possibly access to a timeing gun. Allthough i've never done it before, what do you suggest?

Could using too hi of an octane result in a higher HC? I.e. using 92 octane instead of 89 or 87. And should replacing the o2 sensor will bring the HC lvl down since ecu should adjust?

Something I just thought of, I notice a ticking sound every so often from the engine. Also inspecting the old plugs, 3of4 plugs had white frosted tips, with a blackened outmost ring. I was curious is the tick was a slight misfire.