Have an older mustang 4-cyl, auto. I took it to have e-check performed and it failed the CO(carbon monoxide) on both idle and loaded. Idle failed by 3/100 and loaded failed by 36/100. This car is not F/I, and has no computer system. Just lots of vacume lines, and a CAT. What causes higher CO emissions, and what can be done to help it pass?
Here's info from a book:"CO is produced when there isn't enough oxygen to complete the combustion process. In general terms it is correct to say the richer the mixture, the higher the levels of CO. However, even when the air/fuel mix is at the stoichiometric or chemically correct ratio of 14.7;1, carbon monoxide will be formed due to non-uniform (fuel)droplet sizes, cylinder to cylinder distribution differences, scavenging differences, and combustion differences". So check your float level and blow the carbon out of that engine.
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07:26 PM
Patrick Member
Posts: 36239 From: Vancouver, British Columbia, Canada Registered: Apr 99
I've tried Phil's suggestion in the past and it's never worked for me. However, what HAS worked is to take the air filter element out (just for the test). With a non-computerized engine, removing the filter helps to lean out the mixture. You can also put a LOT of air in the drive-wheel tires to lower the rolling resistance (again, just for the test). Of course, if there's some real bad mechanical problems, no number of shortcuts are going to help.
[This message has been edited by Patrick (edited 07-26-2000).]
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10:43 PM
Jul 26th, 2000
Patrick Member
Posts: 36239 From: Vancouver, British Columbia, Canada Registered: Apr 99
Here's some info from a Monza internet site. Grab a coffee and start reading...
quote
In order of time/money required: * Have the car tested after it's warmed up. The warm engine will burn the fuel/air mixture better than a cold one. Many cars will dump extra fuel into engine when they're cold to help them run better until the engine warms up. * Use high-grade gas. Try a fuel system cleaner. This will help prevent an engine miss, in which the fuel/air mixture isn't burnt and is dumped directly out the exhaust. * Change the air filter. A clogged filter can limit the air your engine is getting, making your air/fuel mixture too rich. * Change the oil. If you're burning oil, contaminants in the oil make the problem worse. * Check the ignition timing. Again, this will help prevent engine misses. Also, if the timing is too advanced, you might not be burning all of the air/fuel mixture before it gets blown out the exhaust. See Robert's notes below. * Change spark plugs, wires, distributor cap and rotor, again, to help prevent engine misses. Make sure the vacuum advance is working correctly. * Fix vacuum leaks. They can cause all sorts of havoc. * Make sure the carb isn't dumping too much fuel into the engine-- this could be due to a number of reasons, for example, leaking from the bowl, wrong carburetor, etc. * Test and fix emissions equipment. A properly tuned engine stands a good chance of passing emissions even without the right equipment, so that's why I put it so far down on this list. But if it's broken or missing, there can be problems (also the inspector might fail you for missing or broken pieces). Check PCV and EGR valves. * Replace catalytic convertor. See Robert's notes below. * Check for and fix engine damage or modifications. Look at the valvetrain, camshaft, and piston rings. A radical cam will let unburned air/fuel into the exhaust, which is bad (for emissions, but not necessarily bad for performance). Burnt valves won't seal correctly, allowing unburnt fuel/air into the exhaust. Worn piston rings will allow oil into the combustion chamber, letting burnt oil into the exhaust. A stretched timing chain will mess up valve timing, which will affect emissions.
Robert Herndon, a licensed California Smog Technician, writes: "When an engine is producing too much "CO's" it is ingesting too much fuel. High "HC's" indicate how the engine is burning the fuel. Common causes of high HC's are Engine Miss, Burnt Valve or a Vaccum Leak. If the valves are in good shape, compression is even and you have no vacuum leaks, you may retard the timing to effect a change in HC emissions. However, in California, you may only reduce the ignition timing 2 degrees either side of the manufacturers specifications. One other cause of high HC production is a faulty Catalytic Converter. Check exhaust pipe temperature in front of and behind the Cat. You should have several hundred degress higher temperature behind the Cat compared to your reading in front of the Cat. An example would be 350 degress in front and 600 degrees after the Cat."
Hopefully there's something there that will help.
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12:01 AM
Oreif Member
Posts: 16460 From: Schaumburg, IL Registered: Jan 2000
You don't say what year Mustang, But does it have the old style A.I.R. pump on it? If it does the inlet filter can be removed and rinsed out with water and Dawn dish soap. The old AIR pumps were used to pump air into the exhaust to aid the catalytic converter. If filter is clogged this will cause you to fail.
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01:33 AM
olympic Member
Posts: 544 From: Saskatchewan,Canada Registered: Oct 1999
We bought the car about a month ago, and since it had been sitting for near a year before we bought it, I decided to burn out all that stale gas, and run a cleaner through it before e-check. All filters have been changed, oil is new and clean, timing is perfect, plugs, cap, rotor, wires, all new, everything looks good. No nasty exhaust smells, doesn't appear to be burning anything. All cylinders have VERY good compression, I will try a higher grade gas, first, and report.
Well, I finally got a chance to take that ol' mustang back to e-check today. All I did was put 93 octane and a bottle of octane boost in the other day. The new certificate says "PASS"(haha! victory!!!)and shows that emmisions are cut 70% from the first two attempts. I changed nothing else. I can't believe it worked, but it did. Good tip Phil. Now, hopefully the Fiero passes when I finally get around to it later this month.
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12:33 AM
Raydar Member
Posts: 40685 From: Carrollton GA. Out in the... country. Registered: Oct 1999