I live in CA where the emission standards are one of the most stringent in the country. In recent years the CARB( California Air Rescorces Board) have lowered the allowable emissions by 30% for many older vehicles, including mine. There goal is to get the older cars off the road. I agree many older cars should not be allowed but not a great clean Mercedes w124 wagon!
The current standard for HC is at or below the allowable levels for many 2007vehicles with much more electronics and designed to run on the reformatted lower octane fuels.
These older cars ar being tested in my area on a Dino at a simulated 15 and 25 mph with HC limits of 57 and 32 respectively. They can be met but everything must be operating perfectly. Here is what I have done and I am sure some of this information is redundant but might be worth revisiting,
This is the normal stuff. Clean fresh oil, air filter,correct Bosch plugs, good wires coils, not to overlook clean good working fuel injectors and O2sensor.
Check for codes and clear them. Do several start cycles after clearing to allow the ECM to relearn. When you are checking things out, pulling vacuum lines and such some codes may come back. Make sure they are all reset before you take it in.
Spark plugs gapped @1mm, the wider the gap the hotter the spark. If your coils won't cut it, they on the way out. If it don't run baby but smooth you will more than likely fail.
No vacuum leaks. Do a smoke test you would be surprised what will show up and don't rush it. Any signs of oil leaking from your oil filler cap is a indication that it might be allowing a intake leak. If oil can get out air can get sucked in.
I Found my EGR valve was leaking from the stem past the bushing. The way the valve is made it allows vacuum to be drawn past the stem and bushing. Even with a new valve some will sneak buy but with a valve 25 years + and 185K it was leaking bad. On a side note I also discovered the EGR valve opens @ 15 MPH.
My other main issue was with the vapor purge solenoid. It was stuck open and with bits of charcoal in in it. Major vacuum leak.
Replaced it and shortly after found more little bits in it. Changed the vapor filter. I haven't found much information on the vapor recovery system and what triggers the ECM to activate the solenoid. I think it is by engine tempature and God only knows what else. I remember reading somewhere the fuel tank level plays into it but I am not convinced. Any verification of how it is operates would be helpful.
The EGR and vapors from the fuel tank are drawn in through the intake and appear not to be metered. I know the purge solenoid is cycled and I Am thinking, hoping,the ECM is making some fuel trim adjustments when the EGR is called on and and the MOT valve is cycling but I don"t know for sure. The fuel vapors would raise the HC levels and if the EGR valve bushing and stem have excess clearance, it could lead to failed emissions.
Take it out and drive it hard for about a hour. The CAT requires temperature to work correctley and try to make a appointment with the smog station so the test is done without sitting around and allowing the CAT to cool off. Buy the way, my converter is the original !
My final attached..... Good for another 2 years.... Can hardly wait!!
Hopes this helps someone and saves them some frustration....... Woodman
The current standard for HC is at or below the allowable levels for many 2007vehicles with much more electronics and designed to run on the reformatted lower octane fuels.
These older cars ar being tested in my area on a Dino at a simulated 15 and 25 mph with HC limits of 57 and 32 respectively. They can be met but everything must be operating perfectly. Here is what I have done and I am sure some of this information is redundant but might be worth revisiting,
This is the normal stuff. Clean fresh oil, air filter,correct Bosch plugs, good wires coils, not to overlook clean good working fuel injectors and O2sensor.
Check for codes and clear them. Do several start cycles after clearing to allow the ECM to relearn. When you are checking things out, pulling vacuum lines and such some codes may come back. Make sure they are all reset before you take it in.
Spark plugs gapped @1mm, the wider the gap the hotter the spark. If your coils won't cut it, they on the way out. If it don't run baby but smooth you will more than likely fail.
No vacuum leaks. Do a smoke test you would be surprised what will show up and don't rush it. Any signs of oil leaking from your oil filler cap is a indication that it might be allowing a intake leak. If oil can get out air can get sucked in.
I Found my EGR valve was leaking from the stem past the bushing. The way the valve is made it allows vacuum to be drawn past the stem and bushing. Even with a new valve some will sneak buy but with a valve 25 years + and 185K it was leaking bad. On a side note I also discovered the EGR valve opens @ 15 MPH.
My other main issue was with the vapor purge solenoid. It was stuck open and with bits of charcoal in in it. Major vacuum leak.
Replaced it and shortly after found more little bits in it. Changed the vapor filter. I haven't found much information on the vapor recovery system and what triggers the ECM to activate the solenoid. I think it is by engine tempature and God only knows what else. I remember reading somewhere the fuel tank level plays into it but I am not convinced. Any verification of how it is operates would be helpful.
The EGR and vapors from the fuel tank are drawn in through the intake and appear not to be metered. I know the purge solenoid is cycled and I Am thinking, hoping,the ECM is making some fuel trim adjustments when the EGR is called on and and the MOT valve is cycling but I don"t know for sure. The fuel vapors would raise the HC levels and if the EGR valve bushing and stem have excess clearance, it could lead to failed emissions.
Take it out and drive it hard for about a hour. The CAT requires temperature to work correctley and try to make a appointment with the smog station so the test is done without sitting around and allowing the CAT to cool off. Buy the way, my converter is the original !
My final attached..... Good for another 2 years.... Can hardly wait!!
Hopes this helps someone and saves them some frustration....... Woodman
s were fully warmed up to spec"
