failed emissions 2nd time.
Thread Starter
8th Gear
Joined: Mar 2011
Posts: 8
Likes: 0
failed emissions 2nd time.
1993 stock motor and exhaust. first test failed all 3 (HC, CO, NO). Found out the head gaskets were bad pulling coolant through the exhaust.
Retseted and failed all 3 again but betteer than the first try.
Can it be the exhaust system is so dirty? Autozone did a check with a tool that he said all it showed was code 12. Something to do with the ignition module.
Any suggestions as to where to start?
thanks
Ken
Retseted and failed all 3 again but betteer than the first try.
Can it be the exhaust system is so dirty? Autozone did a check with a tool that he said all it showed was code 12. Something to do with the ignition module.
Any suggestions as to where to start?
thanks
Ken
Le Mans Master
Joined: Mar 2001
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From: Life is just one big track event. Everything before and after is prep and warm-up and cool-down laps
Cruise-In III Veteran
Cruise-In IV Veteran
St. Jude Donor '12
Yea a 93 we need to see what the emissions numbers are.
You could need new o2 sensors, you need to datalog though to see if the o2 sensors are reacting slow. also what did you have done besides having the heads pulled to replace the head gaskets?
You could need new o2 sensors, you need to datalog though to see if the o2 sensors are reacting slow. also what did you have done besides having the heads pulled to replace the head gaskets?
Thread Starter
8th Gear
Joined: Mar 2011
Posts: 8
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First test had anitfreeze in the exhaust. Heads were extremely dirty with soot.
Test 1
HC 148 should be below 117
CO 1.19 " 0.65%
NO 1102 " 821
Second test:
HC 122
CO .88
NO 1671
While the heads were off I replaced the ignition with MSD unit and a new water pump. Water pump went bad from the cooland getting low from heads.
Thanks for advice.
Ken
Test 1
HC 148 should be below 117
CO 1.19 " 0.65%
NO 1102 " 821
Second test:
HC 122
CO .88
NO 1671
While the heads were off I replaced the ignition with MSD unit and a new water pump. Water pump went bad from the cooland getting low from heads.
Thanks for advice.
Ken
Burning Brakes
Joined: Nov 2008
Posts: 995
Likes: 1
From: Naples Campania
I know those pre-cats get nasty. When I put in my blank Y-pipe it cut them open and they were disgusting. Considering your gaskets were leaking, I would say that caused it. All 3 cats probably need to be replaced. Your O2 sensor is more than likely also trashed.
Le Mans Master
Joined: Mar 2001
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From: Life is just one big track event. Everything before and after is prep and warm-up and cool-down laps
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St. Jude Donor '12
Pay attention - its an LT1, no pre cats. Just 2 cats one on each side.
Ok, so first things first
Did you change the plugs and wires when you did the heads and opti?
Look over every vaccum hose
How long did you drive it after changing the head gasket and the opti?
Ok, so first things first
Did you change the plugs and wires when you did the heads and opti?
Look over every vaccum hose
How long did you drive it after changing the head gasket and the opti?
Thread Starter
8th Gear
Joined: Mar 2011
Posts: 8
Likes: 0
I replaced opti, and the plugs but not the wires. I think the exhaust is trashed with soot and dont know if it will clean up if driven 50 plus miles or more before testing. The car has been driven but not for any great length.
The exhaust ports on the heads were lined with a thick soot layer and I assume the rest of the system is the same.
Does this mean a complete system replacement? Or with the code 12 I could have a misfire issue?
I will look around the motor closer to make sure it is all hoses and wires are connected well
Thanks
Ken
The exhaust ports on the heads were lined with a thick soot layer and I assume the rest of the system is the same.
Does this mean a complete system replacement? Or with the code 12 I could have a misfire issue?
I will look around the motor closer to make sure it is all hoses and wires are connected well
Thanks
Ken
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Le Mans Master
Joined: Mar 2001
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From: Life is just one big track event. Everything before and after is prep and warm-up and cool-down laps
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Cruise-In IV Veteran
St. Jude Donor '12
OK, fill tank with premium gas.
Replace plug wires
Drive it on the highway, back roads,avoid stop and go until that tak of gas is GONE.
Then have a dealer put a tech1 on it and make sure your o2 sensors are not "lazy"
When you go for the next test drive it 20 - 30 miles and get it nice and hot before going to the test station
Replace plug wires
Drive it on the highway, back roads,avoid stop and go until that tak of gas is GONE.
Then have a dealer put a tech1 on it and make sure your o2 sensors are not "lazy"
When you go for the next test drive it 20 - 30 miles and get it nice and hot before going to the test station
Le Mans Master
Joined: Dec 2000
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From: San Diego, Ca
You need to check fuel delivery with a Scanner. If it's a deadon, it's the CATS. Emission testing does nothing more than check the efficiency of combustion and when it's inefficient, the CATs can't scrub up anything. Yours looks rich - coolant, even in small amounts leans it out so it dumps fuel. Too much fuel and it kills the CATs. It also raises combustion temps which skews NOX. See what your Block Learn looks like and repost. There's no magic elixir necessary and it doesn't need to be warmer than the fan (idle threshold) if it's as good as it should be.
