93 Camry failed smog - O2 sensors help

[newbie888]

My 93 Camry v6 failed smog (california) twice. I replaced the Catalyst Converter after the 1st failure but failed the 2nd time. I was told it could be the O2 sensors. I replaced both upstream sensors with the Denso Universal model #234-1057. If I have both sensors installed but disconnect the connector, the check engine light doesn't comes on. Is this normal? This is a single wire O2 sensor. How can I test to see if the wire connection is still good? Also, any information on why it failed smog is greatly appreciated. Btw, this car is from New Mexico so it doesn't have the downstream O2 sensor. It shouldn't be any problem passing california smog, right?


Here are my smog test results:


Test #1 - No replacement part, done at regular smog station
HC (PPM) CO (%) NO (PPM)
MAX AVE MEAS MAX AVE MEAS MAX
AVE MEAS
15 mph 84 27 174 0.49 0.02 0.57 692 147 1810
25 mph 34 16 35 0.46 0.03 0.07 711 134 228



Test #2: Replaced Catalyst converter done at smog only station


HC (PPM) CO (%) NO (PPM)
MAX AVE MEAS MAX AVE MEAS MAX
AVE MEAS
15 mph 84 270 181 0.49 1.99 0.59 692 1912 2814
25 mph 34 220 34 0.46 1.96 0.14 711 1712 398


Thank You

[BMR]

If I'm looking at your test results correctly, it looks like it got slightly worse after replacing the cat?... particularly NOx emissions?

Was the check engine light on when it failed the first test?... is it on now?

Was the second test run immediately after replacing the cat?... The ECU needs a while to "learn" how the new O2 sensors perform.

If none of that applies, it looks like it's failing for NOx's the worst, which, IIRC, can be caused by the EGR system not working correctly. Emissions problems aren't my strong suit, so hopefully someone more knowledgeable will chime in...

[newbie888]

The check engine never came on. I was told to replace the cat after the 1st failure and the 2nd test was done about 3-4 days later. I ran the car for about 1hr (so it's hot) before taking it in for the 2nd test. The smog technician thinks the O2 sensors are bad. Again, no check engine light, even after changing both upstream O2 sensors and left both unconnected. I would think the check engine light would come on. My mechanic said the EGR checks out fine but I'm not certain. How can I check the EGR system, O2 wiring are working properly? What are the emission components involve in passing smog beside the CAT, OS sensor, EGR? How long should I wait/drive the car after changing the CAT and O2 sensors for the ECU system to learn before taking it in for a retest. I haven't done so since replacing the sensors.

Any help would be much appreciated, and thanks in advance.

[BMR]

It could be a lot of things. But like I said, emissions probs aren't my strong suit, so I can't offer much help with detailed diag testing of each system, sorry. Hopefully someone else can chime in here.

[carsrus]

Always a good idea to do a full tune up with something like this. Clean throttle body good, then run sea foam through pcv line and gas. Blow it out on the highway really good then change plugs+wires+ air filter.

At the end of it all pull neg battery cable for good 30 min and drive around for a few days. OBD1 is pretty low tech that's why your not throwing codes.

Does the engine burn oil? If it doesn't burn too bad this probably will solve it.

[hill8570]

Originally Posted by newbie888

no check engine light, even after changing both upstream O2 sensors and left both unconnected. I would think the check engine light would come on

FWIW, I can drive around for days with my upstream O2 sensor (single wire) disconnected, and never throw a CEL. This is on a '95 2.2L, but the tech is similar to the 3VZ. I've seen folks with the same engine mention the same thing, so it's not just my rig.

Not sure why you're having problems. Looks kind of rich, although NO usually doesn't run that high with a rich mixture. Have you checked your air filter, intake hoses and MAF? You'd think the ECU could trim out a slightly rich mixture based on the O2 sensors, but maybe it's too rich to trim out.

[newbie888]

1) The car was tuned up, the timing is good according to my mechanic. What's a good way to clean the throttle?

2) The engine does smell like some burning oil but don't see any major leak. What is an easy way to check for oil leak?

3) I disconnected both battery cables for an hours and reconnected them to reset the ECU. I'm hoping this will help trigger the CEL.

I'm hoping someone can guide me on how to verify the following components:

a) Check if the O2 sensor wire connection from the sensor to the ECU is good. The easy way is to check the wire continuity with a multi-meter but what's the best way since one end of the wire is on the engine and the other is under the glove box.
b) Check if the ECU is not faulty and working fine. I manage to trigger the CEL by disconnecting one of the temperature sensor. There are 2 above the engine (green and red), one triggers the CEL when disconnected but the other doesn't. Again, not sure why. Anyone knows what they are? I think one is the coolant sensor.
c) Check if the new OS sensors are recognized by the ECU. This is the reason why I disconnected the 2 O2 sensors connection to trigger the CEL, then reconnect them to see if it goes off. Any other way to test this.
d) Check if the EGR value is working properly. What/how can I clean it?
e) What are all the emission components involve in a smog check beside the CAT, O2 sensors, EGR value, and the ECU?

Thanks again for all that replied.

[fenixus]

elevated NOx could be a result of failing EGR system (mechanical valve, electro-mechanical vsv, flow modulator or vacuum hoses between them).

EDIT:

hard to read your results, but if I am reading it right it seems that new cat converter made things worse on all 3 HC, CO and NOx tests. what brand of cat was that?

does your Check Engine Light bulb light up when you turn the IGN key ON ? could be burned.

[newbie888]

The smog failed for the 3rd time after changing both upstream O2 sensors, clean the EGR valve, hoses, air flow sensor, the temp & coolant sensors are still new. It looks like the replacement and cleaning wasn't the issue. We did notice steam with coming out of the exhaust pipe and some water dripping out. One of the customer waiting to smog his car thinks it may be a head gasket problem but the car runs great, no overheating, the temp gauge stays at 1/3 and never exceeded the half point mark. I notice the results went up after changing the CAT (test #2), not sure why. The different is test #1 was done at a regular smog station whereas the 2nd was done on a test only station. Are the tests the same on both type of stations? Any suggestion on what I should check for now?

Here are the smog results in better formatting:

Test #1 - No replacement part, test at regular smog station

15 mph (Fail)
HC (PPM) Max: 84, Ave: 27, Meas: 174
CO (%) Max: 0.49, Ave: 0.02, Meas: 0.57
NO (PPM) Max: 692, Ave: 147, Meas: 1810

25 mph (Fail)
HC (PPM) Max: 34, Ave: 16, Meas: 35
CO (%) Max: 0.46, Ave: 0.03, Meas: 0.07
NO (PPM) Max: 711, Ave: 134, Meas: 228

Test #2: Replaced Catalyst converter, retest at smog only station. the results went higher, not sure why.
15 mph (Fail)
HC (PPM) Max: 84, GP: 270, Meas: 181
CO (%) Max: 0.49, GP: 1.99, Meas: 0.59
NO (PPM) Max: 692, GP: 1912, Meas: 2814

25 mph (Pass)
HC (PPM) Max: 34, GP: 220, Meas: 34
CO (%) Max: 0.46, GP: 1.96, Meas: 0.14
NO (PPM) Max: 711, GP: 1712, Meas: 398

Test #3: Replaced both upstream sensors, clean EGR valves/hoses, and visual check the MAF, temp, coolant sensors, re-test at smog only station. the results went down a little.
15 mph (Fail)
HC (PPM) Max: 84, GP: 270, Meas: 162
CO (%) Max: 0.49, GP: 1.99, Meas: 0.55
NO (PPM) Max: 692, GP: 1912, Meas: 2155

25 mph (Pass)
HC (PPM) Max: 34, GP: 220, Meas: 34
CO (%) Max: 0.46, GP: 1.96, Meas: 0.28
NO (PPM) Max: 711, GP: 1712, Meas: 398

Thank You

[Brit101]

You may find this of interest.

http://www.aa1car.com/library/tr1196.htm


Now learn about Sea Foam

Here is the website, $10 a can. You may buy the new Deep Creep for your throttle body cleaning.

www.seafoamsales.com

This is from the testimonials, click on "Our Company" on the top right, and testimonials will drop down, silly place but...

Last two smog tests my old clunker just barely made the cut ('91 Merc Tracer). Don't get me wrong I love my old car, it's just old. A mechanic friend told me about this stuff and it works. Last smog I just added some to the fuel tank and the emissions were somewhat better. But this time only a week ago I did the gas tank thing and put it in the engine oil as directed - ran it for 150 miles. Then I changed the oil (day before the test) and filled up the gas tank with nice fresh gas. I had also changed the wires, spark plugs, cap and rotor, and air cleaner - but I always do that. The day of the test I gave it a good run on the freeway to clean up the engine and heat it up pretty good. Took it in for the test and WOW the emissions were lower than I ever expected; I mean really low almost like a new car! I was skeptical when I first used Sea Foam® two years ago, but I can tell you now this stuff really works, it does! It can't be bad for your car if it cleans up the engine so well you pass your Calif. smog test with flying colors. Amazing stuff!

Walter S

Good luck.

[newbie888]

The sticker under the hood labeled as "62180 3VZ-FE FED & CANADA" CATALYST. It looks like it was built to Federal and not California standards but the replacement CAT is since I had it changed. Could this be the problem all along? Can a car built to Federal standard be made to pass California smog standards? Since this car never passes or registers in California, I'm not eligible for the 2 yr smogs waiver, repair assistance, or the retirement option. Any helpful information on how to get this car passes smog (if it's possible) will be greatly appreciated.

Btw, is the catalyst converter what made the car compliant with the Federal or California standards? or are there other components in the emission system involved?

[Mister_Perkins]

have you by chance checked to see if the check engine light bulb is working correclty? Does it illuminate when you turn the key to the on position *right before start* ?

I saw on a court show one time a dude painted over the CHK ENG light to sell the car. If you've recently purchased the car this would be an important thing to check.

[newbie888]

yes, the check engine is definitely working. It stays lit when I turn the key to the ON position, and displays briefly when the engine starts. When I put it in diagnostic mode by jumping TE1 & E1, the check engine light blinks continuously indicating it didn't detect any error.

[fenixus]

California specs 5s-fe has 2 catalytic converters. 1 is unmonitored (upstream) and resides in the exhaust manifold, while the other (monitored by o2 sensor behind it) is under the car, past the flex pipe.

example 5s-fe differences between calif vs fedral go even deeper and include (but are not limited to):
a) upstream Air Fuel Ratio sensor (wideband) on calif specs instead of HO2 sensor in federal specs
b) different IAC valve, also in 97-99 years having an Air Assist tube connected to the back of engine head (you may have a bolt plug over there instead of a port on back of head)
c) exhaust manifold heat shield is different to accommodate the upstream cat converter (which federal emissions specs car lacks) and also the location of AFR sensor is different than the federal o2 sensor
d) fuel injectors are different
e) lastly the ECU programming is different model.

V6 is surely different too on calif specs as it has 2 AFR sensors upstream instead of 2 o2 sensors (on federal). again 2 catalytic converters and different ECU.

thorough conversion could be pricey.

Originally Posted by newbie888

The sticker under the hood labeled as "62180 3VZ-FE FED & CANADA" CATALYST.
...
Btw, is the catalyst converter what made the car compliant with the Federal or California standards? or are there other components in the emission system involved?

[newbie888]

So, it sounds like it won't pass California smog standard w/o making costly changes as it stands. I wish I had done more research before buying this unregister car.

Thanks again for all the replies!