I failed the emission test on my truck w/ 22r-e. The engine is completely rebuilt with new piston and rings and honed/scratched cylinders. I put only 300 miles on it before doing the emission test and the HC value reached 300 ppm (200 ppm is the limit in Sweden). What can I do?

Two things you might look into that can have a great affect on HC's in the exhaust at the tailpipe:

O2 sensor - tells the engine how much oxygen is in the exhaust stream. You need a certain amount of oxygen in the exhaust for the catalytic converter to do it's work of converting NOx and HC's.

Catalytic Converter - If your Cat is dying, you will measure higher HC's or NOx at the exhaust pipe. Most are honeycomb type units that have two separate catalyst structures in them. The honeycomb that works on HC's might be the culprit.

As usual with a Toyota, make sure the TPS is adjusted properly and the timing is set as per the FSM.

Any other mod's that you have done?

Good luck,

Mike

On a higly modified motor, running rich, with a high flow cat, I'm seeing values of 299-300.

I suspect your converter also.

Make sure you get it good and hot befoe bringing it for testing.

I also suspect that the cat has seen it's best days but for now i just want to pass the test. Somebody told me to put some alcolhol type methanol or ethanol in the tank to make the combustion cleaner or remove a small vacuumhose from the intake to draw in some more air, but then the engine won't idle smoothly. I think I'll try the alcohol before looking for a new cat.
I'm not sure I know where to find the O2 sensor, could that affect the HC levels?
I haven't adjusted the TPS after the rebuilt. Not sure if that has something to do with it but the engine idles a bit high, after releasing the pedal it stays on 1500 rpm fo a while and I have to lift up the pedal from underneath with my foot to lower the idle to 700 rpm.
I've got the timing set at 5 dgrs before TDC with the electrical wires shorted in the diagnosis box.

If the TPS idle adjustment is no correct, idle speed can be off and also the base timing will not be correct (i.e. the timing jumper will have no effect):
http://www.4crawler.com/4x4/CheapTricks/TPS/index.shtml#Troubleshooting

So I would check that. If timing set to 5 BTDC, with the TPS out of adjustment, then the ignition will be retarded and that could lead to high HC. Might also try advancing timing a little to see if that helps cut HC.

The sticking idle may alxo be due to the dash pot:
http://www.4crawler.com/4x4/CheapTricks/TPS/index.shtml#Dashpot

And you can add ~10% ethanol to the gas for the re-test, might help cut HC a little.

I initially failed my emissions test, luckily I was in a shop where they let me use my laptop under the retest.
To pass, I leaned the truck out at idle from 12.4-13:1 to 14.7:1. The leaner I got the more cranky the engine became, but 14.7:1 is still reasonable.

If they test it at fast idle, stalling won't be as big of a deal. You could lean it out youself via a vacuum leak as you've mentioned. If it leaks too much, it will stall, so connect that unplugged vacuum hose to some sort of small filled pipe that you can drill through. IE - take a small pipe, fill it with epoxy, and then drill that hole out slowly until you get to the point where the truck isn't runnin very well, then reexpoxy and go back one drill bit size... Consider it idle air jetting.. :-)

I honestly don't know if the 02 sensor is active at idle. Most vehicle disregard 02 sensor readings at lower RPMs, so I suspect the 22RE is like that. To test, take a reading from your 02 sensor (which is under the drivers seat, typically) and see if it fluctuates back and forth across .5v fairly quickly.. If not, tell us what it reads. Note - do this after the truck is warm, not on initial start up.


Getting a working cat would be the best option, but I know they can be expensive. No experience with the additives that are sold for the purpose of passing tests like this, so you'll have to do your own homework.

Going from 300 to 200 is a 50% reduction in hydrocarbons.. That's going to be tough.

>>>*One thing to remember is high hydrocarbons simply means unburned fuel. A 300 PPM reading is actually very low, that is the limit in our State of Oregon for older vehicles.

Then consider that you have only 300 miles on her, a good long brisk run to fully seat the rings is helpful. Bores that are simply honed often take a thousand miles and sometimes more to seat fully due to minor imperfections.

So before you do too much, I would run the engine more and see if it doesn't just cure itself....*EB

Yeah, 300 PPM is nothing. Mine was blowing over 5000 PPM when it failed.

Turned out the valves weren't closing completely. After adjusting them my HC dropped to below 200.

Here's my thread about. It's a shame all of Thief's posts are blank now.
High HC at idle

I took the shortcut with the ethanol, about 1/4 gallon in 3 gallons of fuel. Also adjusted the air screw a bit, ran the engine really hot and came down to 80 ppm. I hope next year after breaking in the engine I will pass without alcohol.
Thanks a lot for your help.