Hello all - I've been reading some threads and hope you can help me with my failed smog test & what I need to replace and/or clean to make my 3rd gen pass (for personal knowledge & to try not to get ripped off!).

Here are my Smog Numbers

15 mph (25 mph)

NO2
Max = 414 (701)
GP = 1902 (1702)
MEAS = 2516 (2552)

Co2
MEAS = 14.8 (14.7)

02
MEAS = 0.35 (0.51)

HC
Max = 50 (34)
GP = 267 (217)
MEAS = 14 (14)

CO
Max = 0.48 (0.45)
GP = 1.98 (1.95)
MEAS = 0.01 (0.01)

The mech @ Unical said it'll cost me $95 to replace 02 sensor & radiator temp sensor (?) + $60 to re-smog.

For the out-of-state people, yes, I hate the Smog test. Wish I was in your shoes

Thanks a ton.

 

NOx: too hot or too lean... so it looks like he's hoping one or the other, possibly both to fix it. Next time look into a pre-test if they offer it.

 

Had similar issues during the low speed part of the test. Changed out the plugs and made sure that the system was good and hot before the second test and she was good to go.

If you dont have a MIL indicating that the O2 sensors are bad cant imagine why you would want to change it

 

I live in the Bay Area and ran into the same prob 3 months ago. I dont have any advice on what TO DO but what NOT TO DO.

I let them talk me into a $700 cat upgrade. This did fix it but I looked at the re-cert numbers and it only barely passed. I ditto tms2u on the O2 sensor change. I actually just had the indicator light come on and the OBDII code says specifically that its an O2 sensor problem. Funny how your person says it would only cost $95 to replace. The OEM part is $140 and the Stealer wants another $120 for the install. If you do get the O2 sensor replaced, my research of the threads say to only go OEM for any kind of emission sensors.

Not much help but I can empathize. Good luck.

 

my friend had high NO readings on his 97 4runner and it turned out (after reading the OBDII code from my auterra) that it was the front 02 sensor. changed it out (see my writeup at http://www.4runners.org/articles/02sensor) and that fixed the problem.

bob

 

Hi all - Thanks for the input. My "check engine" light came on about 1.5 yrs ago for approx 2 days and I suspected the O2 sensor then, but it disappeared and never came back on, so didn't think much of it after.

Bob_98 - Should I change just the front O2 sensor, or should I do the rear as well?

Islander - Do you know if Kragen or Autozone in the area do OBDII code check for free? I don't have a reader, and wasn't planning to investing in one just yet.

Also, does the O2 sensor replacement require any "re-tuning" or "re-calibrating" of the computer? I am assuming not, but someone told me re-tuning may apply for this 3rd gen.

Thanks again

 

Kragen will not help you. They told me they will sell me one, but thats it. In regards to Autozone. I read threads that say they will read the code for you for free, but that is not true at least in the Bay Area. What they will do is "loan" you the reader for 30 days. You just have to pay a deposit on your CC for $170 which they will refund when you return it. I went to the Autozone in Milbrae. If you go to this one make sure you call ahead because they only have two and I still have one of them :-)

 

your first step is to find an ObdII reader. next, figure what the code is telling you to replace, replace that item.

bob

 

First off I want to thank Bob_98 for his most excellent write up. I will be using this in the near future.

Secondly on a semi related note, I read a thread when researching my P0133 OBDII code that someone on 4x4wire recommends doing a Throttle Body cleaning before replacing the O2 sensor. A very detailed write up on how to do this can be found here . It is a lot cheaper than replacing the O2 sensor since it will only cost some time and $4 for the cleaner. At the very least I hope it will make my 4Runner run pepier. Unfortunately it won't help you since they are going to charge you for each retest :-(.

 

islander - I research the threads & also found something about cleaning the throttle body, so I am hoping to do that this weekend.

I have a chilton manual so I believe the manual gives me the OBDII code breakdown?

Any no...I'm now going to one of those "fail & you don't pay" place this time. I got too cocky last time, so I paid for being too confident in my car...

 

When I read these numbers what I see is basically an engine that's running fine, ei, low HC's, CO's.. I'd take a look at the EGR but I believe the cat is bad, it make the largest reduction in NOX. It is very easy to see if the cat is working. Go to Radioshack and get an IR thermometer or ask a shop to let you use theirs, it'll only take a minute. Get the engine warmed up and see how hot the cat is. It should be around 360C. If it's much lower, it's bad. I forget how to check the EGR, and since I have a 1st gen yours is likely too different anyway.

In short, combustion chamber temps over 2800F produce NOX. EGR cools the burn to lessen NOX. The cat takes care of the other approx 2/3. You could, for example, richen the mixture to lower temps, but you'd fail HC's horribly.

If you have high HC's, that's too much gas and usually caused by a bad O2 sensor.

Frank

 

my friends truck seems to have a power issue, and at crusing speeds the truck kind of bucks, and all the smog test passed except for NOx, could this all be signs of a faulty EGR?