RECENT EMAILS: Exhaust Systems. Aftermarket headers, mufflers, and exhaust pipes. Aftermarket exhaust pipes. California legal exhaust headers must have EO or ARB number.

Question: Will holes in my muffler result in an instant smog failure - I noticed some small perforations where the tail pipe is welded to the muffler...and am wondering if I need to have them patched before going in for a smog test. The holes are pretty small so I guess I will just go for it and hope I pass. If not, do you know if a repair shop can patch a hole in a muffler or would the smog test failure specifically mandate an entire new muffler?

Answer: If the muffler is still intact but has holes consider this: Smog machines calibrated in California (which they all are, every three days) are designed not to allow the testing of vehicles which emit oxygen levels exceeding a smog machines preset limits. In other words, if the holes on the muffler were large enough to where fresh oxygen would be vacuumed in with the emissions stream, the test results would have been incorrect, the machine may not allowed the inspection to continue and/or fail the smog inspection.

If possible, the holes may be welded. The smog technician can tell you before the smog test if the holes will be a problem. Just make sure to inform him/her before the smog test.

Question: I have a 1986 Ford truck that has exhaust headers on it instead of factory cast exhaust manifolds. They are properly hooked up and function exactly the same as the cast manifolds it is just that they are made out of tubing. The smog station said they would not test the truck unless I put the factory manifolds on the engine. These headers have been on the truck for at least 6 years and it has passed smog 2 or 3 times with them on. Do I need to change to factory manifolds?

Answer: The headers you've installed must have an EO (executive order) number. If you can show proof that the units are sold legally in California or are 50 State legal AND possess an EO number, (EO stands for Executive Order- this is the number given to the product by the government, certifying that the component is emissions legal) then you shouldn't have a problem passing the visual portion of the smog inspection.

Most manufactures of aftermarket exhaust or emission components will stamp this number on the actual unit or they will print it the units manual, catalog or some other paperwork which pertains directly to the component in question. In some cases decals with the EO or ARB (Air Resource Board) numbers on them are provided also. You will have to present on of the mentioned forms of proof to the smog station where the car is being tested.

Question: I have a 1989 corvette convertible. It has never failed a smog check. It had two mufflers, however one of them recently fell off. Will it pass a smog check with just one muffler, or does the state of CA require two mufflers to be able to pass a smog check? I need to get a smog check for my DMV registration renewal, and I can't afford to replace the muffler before the registration due date.

Answer: The smog test does not test the muffler. However I don't recommend you take the vehicle in for testing without it. It may cause the smog technician a problem with inserting the emissions probe. If the muffler is still intact but has holes consider this: Smog machines calibrated in California (which they all are, every three days) are designed not to allow the testing of vehicles which emit oxygen levels exceeding a smog machines preset limits.

In other words, if the holes on the muffler were large enough to where fresh oxygen would be vaccumed in with the emissions stream, the test results would have been incorrect, the machine may not allowed the inspection to continue and/or fail the smog inspection.

Question: I have a 1993 Honda Civic VX hatchback (the one with no catalytic converter); The car failed smog. I already replaced the o2 sensor, spark plugs, ignition wires, cap and rotor, PCV valve, Changed OIL and OIL filter, airfilter. It failed emissions with high number in both 15mph and 25 mph test, the reading of CO was 1358@ 15mph and 1112 @25mph. I just noticed there is a crack in the exhaust manifold. Would that be the likely cause?

Answer: You mean the type with no EGR valve. Correct? Also I have to assume the emissions numbers 1358 and 1112 are PPM amounts for NOx. If this is in fact the case you may want to look into the CAT. Vehicles without EGR valves rely heavily on the CAT to lower NOx... however... no diagnosis can be properly conducted until you fix the exhaust leak. The cracked manifold will introduce oxygen to the exhaust stream causing it to burn way to hot, thus creating high NOx. First fix the manifold and then inspect the CAT.

Answer: A "CAT Back" exhaust will not effect the smog test. The state is only concerned with components upstream the CAT. The noise is another issue... once again the state's emissions enforcement bureau (EPA, DMV, BAR) is not concerned with it, however you will have to watch out for the CHP, LAPD, LASD and local law enforcement officers.