91 3SFE Failed Emisison test

[RIP]

How's the compression? Low compression = worn rings = higher oil consumption = high hydrocarbons.

How's the timing? Timing misset = poor combustion and wasted fuel = high hydrocarbons.

An O2 sensor covered with soot is an indication of poor combustion. How did yours look?

Your sticking idle can't be helping. I would either lube the cable or as already suggested SeaFoam the throttle body or both.

[idmetro]

Don't have a compression gauge so can't answer that question. Timing I will double check. The old O2 sensor was soot covered when pulled. I have cleaned the throttle body, seafoamed the engine, fixed the idle and still can't quite pass the emission test.

[xfeejayx]

that 02 sensor helped quite a bit at the 2500.
think your cat might be bad?

[idmetro]

Not sure about the cat. I have a parts car and pulled the cat off it so will try swapping that one in this week to see if it makes a difference. The ceramic grid on the "spare" cat looks nice and clean so I am hopeful.

[idmetro]

Update: Pulled the cat and found 95% of it's internal packing gone so am in the process of replacing it. Was slowed by one of the exhaust manifold studs pulling out of the head (did it with my fingers: !@#$ I must be strong!) a run to the parts store for a helicoil on Sunday evening only to discover they don't have the appropriate drill bit so I'll get one today. Once that's resolved I'll button it all up and I'm certain I'll pass emissions. Will post the final results.

[idmetro]

Swapped in the used cat and finally passed smog with dramatically lower numbers:

1st results 2nd results 3rd results 4th results
2500 rpm test
CO% .72 .78 .67 .21
HC 181 186 146 24
Dilution 14.72 14.15 14.71 15.01

Idle test
CO% .49 .56 .52 .12
HC 377 328 280 23
Dilution 14.69 14.56 14.40 14.79

Thanks for the help. Interesting to see that the engine could almost pass without a cat and equally as interesting to see the drop with a functioning cat.

[xfeejayx]

Originally Posted by xfeejayx

think your cat might be bad?

I win

[Brian R.]

Good call

[RIP]

idmetro - Great to hear your headache is over. It's too bad you had to go to the last resort (cat) to fix it. This is a great thread for others to look at. You showed results of every step you took and quantified them with test results. It's among the best threads on the forum for emissions problems. A big thanks to you.

xfeejayx - When's the party!

[xfeejayx]

Originally Posted by RIP

idmetro - Great to hear your headache is over. It's too bad you had to go to the last resort (cat) to fix it. This is a great thread for others to look at. You showed results of every step you took and quantified them with test results. It's among the best threads on the forum for emissions problems. A big thanks to you.

xfeejayx - When's the party!

I'm with RIP, thanks for the feedback.

Classes start up again Wednesday, party is every day till then

[idmetro]

Thanks for the compliments. I have found this forum immensely helpful and hope others might be spared unecessary pain/frustration/expense as well as being able to get more life from their Camry by what I learned.

One thing I should mention is if you find yourself in a similar position you can (at least on a 91) disconnect the exhaust pipe from the bottom of the cat, shine a flashlight in there and get a pretty good view of the physical condition of the cat (all for the $2.50 cost of the gasket). In my case it was immediately obvious that a change-out would be needed. I found it easier to pull the cat, the exhaust manifold and the bracket supporting the cat to the engine block as a unit and then work on them outside of the engine bay.