J30 smog
J30 smog
I have a 95 j30 that just failed smog as a gross polluter. The pre test at 15 & 25 mph were fine and well within specs. Tested and failed. Did a another pre test right after and was well within specs and then spiked high on HC and CO2. Both pre tested on a dyno. I've changed the MAF, plugs, air filter and fuel filter(before test). No check engine light so its i cant get codes. But the smog tech says its running rich which i can smell it. I put 91 oct in before the test and beat it up and down the freeway to get it hot before the test. Runs smooth and doesnt smoke. 189k on it. CA car. Couldn't find anything in the forum and im just wondering what i should do next.
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Q451990
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- Joined: Tue Jul 23, 2002 8:21 am
- Car: 1990 Q45 - 118K, 2022 Toyota 4 Runner, 2004 Frontier M/T - 108K, 2012 Xterra (Mom's), 2023 Rogue (Inlaws)
- Location: Columbia, SC
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Re: J30 smog
to NICO!I know old sluggish O2 sensors can cause a car to run rich, but I have no idea if that's your problem or not. If they've never been replaced, they're well overdue just as preventative maintence. We've found www.sparkplugs.com to be a good source for discounted sensors.
Other thoughts would be faulty knock sensors, which would cause the engine to run richer to protect from spark knock. These will not throw a check engine light, but would have stored codes.
I would also clean the port where your EGR valve enters the intake. Those tend to clog up with carbon, preventing the EGR gases from getting much past the valve and actually into the intake.
Hopefully someone with more experience with smog tests can come along shortly to give you some more input.
Good luck!
Heath