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Registered
1985 2wd Truck XtaCb
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11 Posts
Discussion Starter #1
Hi y'all!

My 1984 Tercel (Wagon 2wd) failed CA smog recently with high NO levels.
I replaced the Oxygen sensor and spark plugs, and added a new air filter.

While looking for the EGR, I accidentally altered the timing, which I proceeded to put back into spec (5 deg. with vacuum advance plugged).

When I took the car back to the Smog Test guy, it failed for different reasons. NO levels were fine, but HC and CO levels were up. And he marked down the timing as being at 1 degree, which is also a point of smog failure. He unfortunately was too busy and at the end of the day to talk about it.

I'm confused. Did I read it wrong? I'm looking at the numbers printed on the timing belt cover, and 5 degrees is the second indent from the right, which is where it's sitting when I shoot the timing light at it at idle with a warm engine.

Any ideas of what I might be doing wrong?

Thanks,
Marshall
 

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Senior TN Member
Porsche
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7,508 Posts
Check timing with vacuum disconnected I think. In CA, you're allowed base-timing +/-3 degrees. So if base-timing is 5-degrees, you're allowed anywhere from 2 to 8 degrees BTDC.

There's a criss-cross function of NOx vs. HC/CO. More ignition advance will increase NOx, but lower HC/CO. Less timing lowers NOx but increases HC/CO.

If your latest test passed NOx and HC/CO and only failed base-timing, I would nudge timing 1-degree more to pass while not increasing NOx too much.

Good luck!
 

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84 tercel 4wd wagon
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13 Posts
Make sure to disconnect your distributors vacuum advance before altering your timing and reconnect it when you are finished. 5* will pass your emissions test. After your emissions test you can set it to 10* and you will get some extra power out of it. Tercel4wd.com has a bunch info on these cars 2wd tercels are welcome as well. Everything you will ever need to know about the 3a engine is on that site. Hope to see you there.
 
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