'99 Sonoma Failing CA Smog

My 99 Sonoma - 2.2L - just tanked on the %^($#! new CA smog test. Failed the NO measurement at 25 mph, which I understand is new, more stringent test. Max is 527, I measured 876. Passed at idle. HC measure 0.0 (pass), CO measured 0.01 (pass). Anybody got an idea of what I am looking at with this high NO measurement? Truck feels like its running fine. No "Check Engine" light ever. New AC platinum plugs a few months ago. Thing doesn't even HAVE an EGR valve, which would be my first suspect. I am told that a lot of vehicles are failing on this test.

Thanks

Reply to
stevejoin
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I assume you went to a test only smog station, lots of these fail in high mileage vehicles. Try the cheap things first: Change the oil, this helps Change the air filter, unless it's clean Check the timing, this is critical, advanced timing will give you high NOX readings. If that doesn't work then the catalytic converter and egr valve are next. The electric EGR valve for your vehicle is by GP Sorensen and is part number 7792700. This valve is expensive and likely not the culprit and can be checked for operation by any "non test only" smog shop. Smog stations in your area can be located at

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Reply to
dougmcp

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Reply to
One-Shot Scot

One reason I prefer living in Florida. No Emmisions tests. Just have to make sure they aren?t blown away by Hurricanes.

Reply to
BadBow99S10

Just in the interest of helping anybody who has this same problem, here's the GM fix so far. I took it to big GM dealer early yesterday a.m.. Sat and waited for emissions guy to get in. He took one look at previous test results and said, "Oh, you're running 89 octane, aren't you? (yes, I was) "Run it out, run a full tank of Chevron 93 through it, bring it back to me when its almost empty. I will test it while you wait and I guarantee it will pass." He never even looked at the truck or tested it. He told me, "I don't have to look at it. There's nothing wrong with your truck." He explained that -- since '99 and later 2.2 do NOT have an EGR system -- most if not all will fail new, stricter CA NOx standards at slow speed IF you take the test on regular (89 octane) gas.

Well, so at least the EGR controversy is settled. It'll take a while to run a full tank of 93 octane through it. Then I'll take the test again.

BadBow99S10 wrote:

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Reply to
stevejoin

Sorry about the misinformation on the EGR. I was sure it was on that engine, only missed by a year, Oops! I be having the little woman administer 6 lashes with a wet noodle. Good to know about the high octane thing from an expert. I tried that and an octane booster a well and still failed but mine engine was differerent ('93 4.3 V/6). Good luck, hope it passes, this new CA emissions test is a PITA.

Reply to
dougmcp

Sorry about the misinformation on the EGR. I was sure it was on that engine, only missed by a year, Oops! I be having the little woman administer 6 lashes with a wet noodle. Good to know about the high octane thing from an expert. I tried that and an octane booster a well and still failed but my engine was differerent ('93 4.3 V/6). Good luck, hope it passes, this new CA emissions test is a PITA.

Reply to
dougmcp

I have a Toyota that failed the Nox test at a "test only" shop in Calif. and the guy told me what I already knew,"change the cat.converter" Before the new converter the NOX level was way above the 936 ppm max allowed.After the new converter installation the reading was 13 ppm !! Then I repaired the leaking intake mani gasket that caused the rough idle and the damage to the Cat converter. Best...Brian O.

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Reply to
Brian Orion

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