1988 chev 2.8L emission fail

1988 chev celebrity 2.8L failed emission tst. readings HC 1.63 gpm CO 14.77 gpm NOx 1.18 gpm test limit HC 0.80 gpm CO 15.00 gpm NOx 2.00 gpm this car has always passed test with readings well below the test limits. I replaced plugs and wires prior to to test. Shop suggests major tune-up and o2 sensor. Because all readings are high is it possible car was not at operating temp when test was performed?, is there any check of operating temp before test systems begins? thanks for any thoughts/info.
Reply to
nick99
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Yes, it might have failed because the catalytic converter was not hot enough to function.

No.

Reply to
Mike Walsh

Reply to
Shep

Did you drive the car for at least 20 min before the test to warm it up? Did you leave the car with them for the test or did you drive in and get it tested right away?

Do you have the test results from last time? I should think there would not be any dramatic changes unless something broke in between the tests.

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Reply to
William R. Watt

There's not much more to replace for a "major" tune-up other then plugs and wires. If it still uses a distributor, maybe a good cap and rotor could be thrown on, though I thought the 88's were DIS (not sure though). Definitely change the oil (dirty oil can increase emissions readings). An air filter if it hasn't been changed recently. As far as the O2 sensor goes, if it has over 60k miles on the sensor, probably wouldn't hurt to change it (and with double the HC output, probably a good suggestion). If you are getting a lot of engine blow-by (which you can check by looking in the breather tube, one valve cover will have the PCV valve assembly and the other just a breather tube connected to the air intake somewhere after the air filter, if that hose shows oil in it, you can bet you've got blow-by or a bad PCV valve) one trick you could try is to clean the PCV valve, then put some electrical tape over it (one piece right over the opening with each end going slightly up the sides, then one wrap around the outside) then pop it back in (effectively rendering it inoperative which is illegal). You'll need to do the same on the breather tube, but don't plug it off all the way, you'll need to allow it to vent outside the intake track without looking like it's disconnected. Did I mention that would be illegal? And if you do disconnect it, by all means reconnect it after the test! But it may get you through the test. I suppose I'll hear a bunch of flak for even suggesting that but if you're not intending on keeping the car much longer and you just need some more time with it...what the hell. There are much bigger, corporate polluters out there with gov't issued waivers, and one 2.8L engine on the road for another year won't break the greenhouse gas bank. And let the bashing begin! :P

Reply to
Todd

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