'94 Chevy Astro Smog Results

[ASTROMFG]

Greetings!

I went in for a smog check today and failed due to defective ignition timing it was set at (04 ATDC) advanced by a few degrees. The emission numbers barely passed during the first test. The tech adjusted the timing to 00 TDC and we underwent another test to find that the NOX levels skyrocketed and the hydrocarbons increased as well . The change in ignition timing had an adverse affect on the emissions so what could possibly be the culprit? The van has 184k miles.

[markmitch]

ask Chevy Maher he knows all, lol just stopped to say hello I am from Nor Cal.. Mark

[chevymaher]

The change in ignition timing had an adverse affect on the emissions so what could possibly be the culprit?

People that run the state of calif are idiots, that is the culprit. It passed emissions, they re-tuned it and it didn't pass anymore. Really do I need to say more.
Reading went the opposite direction that they should have for the timing change. So I thinking the timing chain is stretched and that is why the timing was advanced to compensate.
De-carbon the engine with some water. Shoot water into the intake with a squirt bottle and let it smoke. Revving the engine at the same time. Run a gallon of lacquer thinner in a tank of gas to clean out the catalytic converter. That will help the mech end of things.
Check your vacuum lines, leaks are terrible for this. Tune up, incomplete combustion never helps. Some lucas injector cleaner, Same thing raw and not itomized gas kills emissions. Check the EGR for sticking, PCV also.
Before the test. Disconnect the battery 20 minutes to clear the computer. Drive it like a race car an hour before the test get that engine running hot and clean. Jackrabbit starts, run it hard on the freeway to the floor some. Just don't let it idle around. Computer settings will reset as much toward performance as the POS computer will allow.
Once you pass re-advance the timing untill the next test. And go through all this again. No matter what the morons say your engine obviously likes the timing better.

[Lumpy]

Sounds like fun. In CA, you are legally mandated to pay someone to take your engine OUT of compliance. Then they issue you a warning that you must have your engine brought into compliance.

I'm embarassed that I was born there...


Lump

[icebrrg3rd]

Question. How did they determine that you were at 4° ATDC? '94 is still OBD1, IIRC you'd use a timing light on the front timing marks? If so, are they accurate? When swapping my V8, the manual says to note the TRUE TDC and mark it, so when the timing cover is put back on, the timing marks could be checked to see if they were really accurate. So a mass-produced engine that's 20 years old, it's timing marks are dead nuts on, right?!? Yours was 4° off? Probably within tolerance specs, especially if you were running w/o a CHECK ENGINE light and passing emissions.

So how much did it cost you to FAIL? They get their pockets lined from it?

-Andrew

[97cargocrawler]

I seriously doubt they really checked and if they did I doubt they read it accurately. I had my smog test the other day. When I got home (after passing) I swapped out the distributor. I went to check my timing afterwards and I couldn't even see the index on the engine cover through the fan shroud and all the other crap in the way AND it was so covered in grease it was hidden. I even had to make a silver paint pen mark on the balancer before I could see that to compare. So I KNOW my smog guy just went through the motions and typed in whatever it was supposed to be even though he didn't see sheeeit.

Those number are real bad though regardless. With number that bad I would replace the catalytic converter if you have not already.

Mine for comparison:

[californiaastroluv76]

smog1.jpg

Smog2.jpg

Greetings!

I went in for a smog check today and failed due to defective ignition timing it was set at (04 ATDC) advanced by a few degrees. The emission numbers barely passed during the first test. The tech adjusted the timing to 00 TDC and we underwent another test to find that the NOX levels skyrocketed and the hydrocarbons increased as well . The change in ignition timing had an adverse affect on the emissions so what could possibly be the culprit? The van has 184k miles.

clean your EGR Valve and replace your air filter.

http://www.youtube.com/watch?v=51z-k4YRHI4