[Vegas]

The first time I took my 91 Previa in for smog, it failed badly... gross polluter, tons of reds, etc.

I didn't give up, so I bought and replaced some parts: new spark plugs, spark plug wires, new catalytic convertor, up and down o2 sensors, cleaned air filter

The old catalytic convertor was missing half of it inside, with a giant hole... not sure how that happened. That was the biggest culprit for sure.

When I took the van in for smog again today, it still failed. The results were a ton better, and it's very close to passing... but fails in the 15 mph test. 25 mph passes though.


I'm out of ideas on how to fix this thing :headbang:

 

[AlaricD]

What particular pollutant was out of range?
High NOx would mean it's running too lean, maybe a vacuum leak that doesn't manifest itself all the time and conditions may be right at the speed of the test.

High CO could mean too rich a mixture, high hydrocarbons also would point to that (but can also mean too lean, as well).

I believe you have to jump two connectors in the diagnostic connector under the seat to be able to properly set the timing, as well.

 

[cmh1129]

Running some fuel system cleaner through it wouldn't hurt. We had a car one time that failed emissions, we ran some fuel cleaner through it and it passes afterwards. I would also check the timing.

Good luck....

 

[Vegas]

Thanks for the help. I actually bought some fuel system cleaner yesterday, just waiting for the tank to go near empty so I can use it

I believe it was NOx but I'll have to double check

Also, when the car is idling at lower RPMs, I can hear a little bit of missfiring... could that be related to timing as well?

 

[AlaricD]

Misfiring can result in higher NOx. Misfire can result from a bad coil or hall effect sensor (or points and condensor if you've got a very old car). Could also be predetonation causing it.

The 91 isn't supercharged, so 89 octane can cut down on predetonation -- 91 may actually be TOO high.

A Seafoam treatment might just knock out some of the more easily removed carbon deposits.

How long of a window do you have on passing inspection before they impound or whatever it is they do?

 

[Vegas]

Good info.. I'm not entirely sure if it's misfiring, it might actually be an exhaust leak because I only hear it at idle

As for the octane, I've actually been using 91 for the smog... I'll try 89 next time

I think I have about another month before it's due to figure this out

 

[AlaricD]

Exhaust leaks forward of the catalytic converter can also be problematic.

 

[cmh1129]

I have a 91 as well... i get my best MPG from 91 octane, but it pulls much harder and performes better with 87...

 

[Vegas]

I was able to get it to pass with some Alcohol

I wrote about it here: http://grandmighty.com/index.php/2010/07/third-times-the-charm/

 

[SuperchargedMR2]

I was able to get it to pass with some Alcohol

I wrote about it here: http://grandmighty.com/index.php/2010/07/third-times-the-charm/

Interesting story & I'm glad it passed. :thumbsup: It sounds like it would be easy to put a bottle of HEET into a full tank too & still pass. You mentioned bumper paint in your list for $4. What did you do with painting the bumpers for only $4. :naughty:

 

[Vegas]

^ about the bumper paint, I was originally going to use that on the wiper arms... but haven't gotten around to it. I don't think I'm even going to bother, so I'll have to revise the list :facepalm: