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Failed CA SMOG

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90GMCJim

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I went to get smogged today and failed. I just recently purchased from a friend. It sat for a while. I drove it around and put some fresh gas. no smoke no issues.

Can anyone point me in the right direction on where to start and what to replace first? Appreciate any help

Thank you
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HC's in general is from incomplete combustion. Prob look at spark plugs/wires/cap/rotor stuff. Make sure charging system is good.

CO's generally are from being to rich and yours look ok.

The NO's if I'm remembering are potentially from a bad EGR, or cat converter.

These are all off memory, and I'm getting old... lol
 
What year, with cat NA in inspection. HC are unburnt fuel, and NO is high combustion temps. With out a cat No are hard to get down. I think Cal is moving the line to make you give up these old cars.

You can retard the time a couple of degrees, open the gap on the plug to .060", Make sure the cooling system is in top shape, since no cat maybe 180° thermostat. EGR show functional on test report, there still may be a restriction in the manifold passages. All this esp the plug gap is for test only.
1/4 to 1/2 of e85 mixed with 87 might also help with the NO.
If the carb air fuel screws are unsealed, you can adjust ea screw for best rpm, then close it 1/4 turn. Make sure you have a nice clean air filter, clean oil helps too, some of the HC came be from dirty oil in the pcv system.
 
Wes Harden said:
What year, with cat NA in inspection. HC are unburnt fuel, and NO is high combustion temps. With out a cat No are hard to get down. I think Cal is moving the line to make you give up these old cars.

You can retard the time a couple of degrees, open the gap on the plug to .060", Make sure the cooling system is in top shape, since no cat maybe 180° thermostat. EGR show functional on test report, there still may be a restriction in the manifold passages. All this esp the plug gap is for test only.
1/4 to 1/2 of e85 mixed with 87 might also help with the NO.
If the carb air fuel screws are unsealed, you can adjust ea screw for best rpm, then close it 1/4 turn. Make sure you have a nice clean air filter, clean oil helps too, some of the HC came be from dirty oil in the pcv system.
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1990

As soon as I parked the car at the smog shop the radiator showed signs of leaking. Looking to replace that as well.

Thank you for the advice. Will gap the plugs and change a few things out. Going to call around and see about replacing the CAT.

Thanks again
 
Since you do have a catalytic converter no 180° thermostat.
Use a 192-195°. Since tbi no carb adjustments.
You should run the engine with air cleaner of. Watch the injector spray pattern, should be a nice cone shape curtain. No drips or open segments.
The regular timing is computer controlled, but base timing is set manually. There is a comp timing disable connector by the distributor for setting the base timing. One wire connector. Disconnect to set timing. 0 TDC for smog test.
 
Wes Harden said:
Since you do have a catalytic converter no 180° thermostat.
Use a 192-195°. Since tbi no carb adjustments.
You should run the engine with air cleaner of. Watch the injector spray pattern, should be a nice cone shape curtain. No drips or open segments.
The regular timing is computer controlled, but base timing is set manually. There is a comp timing disable connector by the distributor for setting the base timing. One wire connector. Disconnect to set timing. 0 TDC for smog test.
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Thank you very much

Any recommendations on radiator.
 
A timing light works good to see injector spray pattern, hook it up and shine in in the TB, like Wes said you want a nice cone not dribbles.
 
^^^ This is true, but can be negotiated away just like any other business deal
 
Move to an American state.

Which county are you in? I was in San Bernandino and they seemed to be more helpful than when I was in Orange county. Clean oil, run it until its warmed up before you pull into the shop, those helped me.
 
Yes keep the cat warm don't let it cool off while waiting to be tested, 3 min high high idle used to be part of the procedure for imediate retest after fail. This was in the 90s.
Still a good idea before a test.
 
Any luck passing the smog with a new cat?

Had a failed test years ago after I thought I could just take my k5 out of the driveway and zip over to the smog guys. It had been sitting for months. Guy told me “any vehicle that fails by a little can pass by a little… go change the oil and gas and bring it back fully warmed up”

It makes a pretty big difference.

I’ve always been able to get through the test with new oil and a tank that is MAJORITY fresh gas. Then take it in hot.
 
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Although my last test caused me some issues. I had a a spark plug wire with intermittent short- unburnt fuel going out the pipe. Then after figuring it out, went back and the smog guy couldn’t figure out how to operate a manual trans on the dyno- refused to shift into a gear that would keep the rpm and wheel speed in their correct ranges…. Then said the state of CA would not allow him to shift? He told me to remove the lift and big tires and put the truck back to 100 percent stock condition before coming back. I told him to learn how to drive a stick shift and then went down the street to another guy. Passed with zero drama.
 
So far I changed oil and spark plugs. I’m waiting for my new radiator to show up. The exhaust shop is like 1 hr away so I wanted to address the leaking radiator first. Hopefully by next week I’ll be out of the exhaust shop and getting a new smog
 
90GMCJim said:
So far I changed oil and spark plugs. I’m waiting for my new radiator to show up. The exhaust shop is like 1 hr away so I wanted to address the leaking radiator first. Hopefully by next week I’ll be out of the exhaust shop and getting a new smog
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Did you get a radiator from Heath?
 
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