Hey guys, Need some help
Please examine this photo for further confusion




Recently: I have gotten an Oil change, changed spark plugs, cleaned airfilter, cleaned distributer cap, and had my AC serviced a little (I don't know if any of this information helps, but here it is anyway.) - Oh yea, a new battery too.

The smog-man told me I probably need a new Cat Converter. Only problem with that is I recently replaced it with a new one less than 2 years ago (the old one was stolen.) Could i need to really replace it again? THAT SOON? I was sure they lasted for thousands of miles?

or could I need to have my mechanic check something else out? (he's an honest fella)

The truck is a 1992 pick up 2.4L Engine manual transmission with 66,670 miles on it.

Before I head over to my mechanic in an hour I was hoping to get any advice on the subject matter.

Please help oh knowledgable Toyota gurus

 

You failed nox. Possible causes: timing advanced too far, carbon build up in chamber, inoperable egr valve, cat converter. With you mileage, I would lean towards an EGR issue. Put a vacuum pump on the top of the valve and see if the engine stumbles or dies. I suspect it will, that means it is working. Next check for vacuum from the egr modulator(round doo-hicky with 3 vacuum lines on top, next to egr valve). Put the vacuum line from the top of egr valve to a vacuum gauge. You should see vacuum while lightly revving the engine to 3k. If no vacuum, check for leaks, plugged up lines. If that checks good, you probably need a vacuum modulator and/or vsv. I typically replace them at the same time.

 

Thank you very Much J2the-e, I will be certain to let my mechanic know, if he doesn't already!

 

If he is a CA certified smog tech, he better know these things!

 

Well my mechanic is separate from the smog man

 

Good luck! Be sure to update this thread for future users!

 

Will do, I'm at the mechanic now, as I come with a solution I will update you!

 

So the EGR valve/system (I think thats what its called) and the vacuum were both fine, Turns out my oxygen sensor was bad, and I need a new catalytic Converter. I will be getting both pieces replaced and serviced tomorrow, will update this post after the re-inspection of my smog

 

Let us know. Your O2 sensor may have been bad, but with your low O2 numbers it was not contributing to your smog problems. Similarly, your low HC and CO numbers suggest your Cat is okay; the Cat has a small effect on NOx but mostly HC and CO. But your mechanic saw something I didn't.

The most likely cause is somewhere in the EGR system. That is its job; that's its only job. But if your new O2 sensor and Cat clear it up for you, that's great.

 

I had this same issue on my recent Smog check. First time I have ever had issues with passing smog.

In my case, the thing that was causing the issue and ultimately solved the problem was cleaning out the upper intake. The upper intake had a bunch of sludge and oil built up that was blocking several of the vacuum lines, rendering much of the EGR system ineffective. If you tested the components by themselves, they checked out fine, but running on the vehicle they were not operating properly.

In my case, all I had to do was pop off the throttle body and shine a flashlight inside and I could see the issue quite clearly.

This might not be your issue, but if it is a higher mileage engine its a possibility. The other possible one could also be the intake pipe. I have had a friend who had a similar issue when the rubber elbow in the intake pipe was cracked or had a small hole. This was letting in unmetered air at idle that the computer couldn't adjust for and caused him a bunch of problems (including idling issues).

Just another couple of thoughts.

 

So I'm here now, and the mechanic speculates that the Cat still needs replacing, but we're changing out the O2 censor anyway (the old one is bad) he says my EGR System is fully functional and is doing its job..

 

So after a nervous 20 minutes at the smog station, I passed!



So under the advice of the Muffler guy (who was going to replace my Cat converter) I didn't need replacing of my Catalytic converter, Instead I went back to my mechanic and we went ahead and replaced the old O2 sensor. My numbers were nearly cut in half, Likely because of the replaced (front) O2 censor ($77).

My mechanic determined my EGR system was fully functional and (the vacuum) was operational. Timing was fine, everything else was fine.

The only other change we made was an alternator belt change but that doesn't even matter.

Thank you for everyone who helped contribute to the discussion- for your knowledge, assistance, and optimism!

 

Good to hear the yota is good now...sweet

 

Congrats.

And yet both your HC and CO went UP (HC all the way to the limit) You may have to face this again in 2 years (but by then, the Zombie apocalypse could have happened).

Drive safely.

 

Aftermarket cats don't last two years on high mileage vehicles. You'll have to replace it every time you have a smog check. The O2 sensors should last 90K miles.