Cal Club Autocross Forums

While I know that passing the smog test is an obligation of the seller, for $800 purchase price I was ready to make a few concessions

I have some good news: the truck passed the smog test with flying colors! I first replaced the oxygen sensors, but that didn't do anything as it still failed the test. What made the big difference was the catalytic converter.
Thank you all for the advice!

Mihail

Congrats

Courious what type of O2 sensor was in there (# of wires).

New cat often fixes all. Was it the original that you replaced?

If it wasn't, I'd still keep an eye on things. A bad running motor over works the cat, which leads to it's distruction, which leads to smog fail, which leads to new cat, which leads to smog pass. But if you never fix the problem, you get caught in that loop of replacing the cat every few years. If it was the original on there, it's definitly reached the end of its normal service life.

Jay W

Jayson Woodruff wrote:Courious what type of O2 sensor was in there (# of wires).

New cat often fixes all. Was it the original that you replaced?

If it wasn't, I'd still keep an eye on things. A bad running motor over works the cat, which leads to it's distruction, which leads to smog fail, which leads to new cat, which leads to smog pass. But if you never fix the problem, you get caught in that loop of replacing the cat every few years. If it was the original on there, it's definitly reached the end of its normal service life.

Jay W

The two O2 sensors were of the 4-wire type. I replaced them with Bosch 15718 4-wire sensors ($33 each from Amazon). The cat had a Ford part number stamping and by the amount of rust and soot it had accumulated it sure looked like the original that was put there back in 1992. I've replaced the spark plugs, air filter and fuel filter and the engine runs smoothly. I haven't checked the timing and I am not sure if it can be adjusted at all on this model. A shop in Simi Valley asked $55 for smog pre-test and additional $150 for diagnostics. Yeah, right. I'd much rather replace the cat ($250 from Magnaflow) each time I need to pass the smog test

While not cheap new cat can cure all. Brothers toyota smog numbers all dropped 90% with new cat installed, passed easily!