Hi all,

I have a look at some of the other threads on failed smogs, and could still use some advice.

Truck is a 92 toyota pickup dlx, 22-re, 4wd, manual trans. A few years back I had the engine completely proffessionally rebuilt- top to bottom. Roughly 30k miles on it since.
Shortly afterwatds I moved to CA and failed smog miserable- ended up replacing both O2 sensors (original brand parts) and the catalytic converter. Sailed through smog w/o a problem.

Then this past year I blew a head gasket (looks like rebuilder had messed up, and despite a 10 yr warranty I got ****** as they had gone out of business)

Anyway- got that fixed (new cylinder head and new thermostat) and I just failed smog again. Emissions were actually within limits- but my timing was off by 6 degrees. But the worrying part is that the NOx emmissions just barely passed (and might not after timing is adjusted), and they are much, much higher then they had been.

So, I'm thinking something (EGR? Cat?, O2 sensor?) got fried when all that water/coolant vapor entered the system when the head gasket went. Not my area of expertise though so thoughts on were/how to start? What is most likely to have fried?

anyway- here are the numbers - passing test from 2yrs ago followed by recent failure:
15mph test: RPM1563 %co2 14.8 %O2 0.4 HC(ppm)14 co%0.00 NO(ppm)372
1575 14.9 0.4 40 0.17 1053

25mph Test: RPM2506 %co2 14.9 %O2 0.0 HC(ppm)12 co%0.00 NO(ppm)97
1719 15.0 0.1 22 0/09 653

So any thoughts on the most likely suspects- either from the change in results, or what is likely to have been damaged by coolant entering the system?

I should also mention that all the spark plug wiring is pretty much new (less then 6 months old).

 

looks like your cat is hurting. replace that and you should be ok.

 

Okay, timing was off 6. Which way? Advanced or retarded?
If you were off advanced, retarding to stock timing will lower your NOx. May not be enough to pass but keep in mind that a blown HG will likely take the converter out with it so don't be surprised.

And also keep in mind that Cali smog tests don't activate the EGR system (I can drive around all day without and EGR code, but when I happen to hold over 35 for at least 5 minutes I get the code) so if the cat is working well, even a totally blocked EGR system won't fail you... as long as it looks like all the parts are there.

And don't think you'll hit the local auto parts store for a new converter here in Cali. You can't "technically" even install a converter in a truck unless you're BAR certified and the converter meets certain labelling criteria, meaning you can't even hit the wrecking yard to buy one- most yards won't even sell it to you. Maybe you can find one from a private party but better take the truck to a different shop for the follow-up retest.