Help passing the sniffer!
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Posting Guru
Joined: Jun 2001
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From: Conyers
Help passing the sniffer!
I just failed a sniffer, due to bad plugs, so I hope. Looking at 'em, I wonder why the truck even ran. They were REAL sooted up with gas. I changed the plugs. I tried to get it retested today but the sorry SOBs wouldn't/ couldn't do it so my truck is now illegal to drive. No emmissions, no tag. My readings at 25mph were: HCppm-212 "allowed is 179"; CO%- 2.85 "allowed 2.22"; NOx ppm-713 "Allowed 2457". My readings at 15mph were: HCppm- 233 "allowed 183"; CO% ppm- 3.5 "allowed 1.65"; NOx ppm- 722 "allowed 2638".
Damn smog *****...I set the carb to 3 stages lean on the power mode and cruise since then. My truck doesn't like it at ALL! Anyone have any ideas to help me pass?
Damn smog *****...I set the carb to 3 stages lean on the power mode and cruise since then. My truck doesn't like it at ALL! Anyone have any ideas to help me pass?
Junior User
Joined: Aug 2002
Posts: 67
Likes: 0
From: Irvine
Help passing the sniffer!
Hi,
O.K. first off your carburator is not using the power or main metering circuits at 15 and 25 MPH; it is using the off idle port and low cruise circuits, so put your carb back to the way the truck likes it. Next thing where is your base timing set? Based on your CO and HC readings I would advance the base timming a little. Is your fuel system clean? Try running some carb cleaner in the gas, or use the spray type. You could also try hotter plugs and a hotter thermostat (I use 195 deg myself). I would also lean the idle as much as possible, but not so much as to make the engine run rough. Do you do more in town driving than highway? If so I would recomend driving about an hour or so before your re-test, and/or using a can of GM top engine cleaner to eat the carbon deposites out of the combustion chamber(DON'T USE WATER). Also be sure to do the following a day or so before your re-test: Change the engine oil, new air filter, new fuel filter, clean/new PCV valve and hose, make sure the timing is set to factory specs, make sure all hoses are connected to what thy are suposed to be connected to, and lastly- run the vehicle at least half an hour before testing.
Good luck!
O.K. first off your carburator is not using the power or main metering circuits at 15 and 25 MPH; it is using the off idle port and low cruise circuits, so put your carb back to the way the truck likes it. Next thing where is your base timing set? Based on your CO and HC readings I would advance the base timming a little. Is your fuel system clean? Try running some carb cleaner in the gas, or use the spray type. You could also try hotter plugs and a hotter thermostat (I use 195 deg myself). I would also lean the idle as much as possible, but not so much as to make the engine run rough. Do you do more in town driving than highway? If so I would recomend driving about an hour or so before your re-test, and/or using a can of GM top engine cleaner to eat the carbon deposites out of the combustion chamber(DON'T USE WATER). Also be sure to do the following a day or so before your re-test: Change the engine oil, new air filter, new fuel filter, clean/new PCV valve and hose, make sure the timing is set to factory specs, make sure all hoses are connected to what thy are suposed to be connected to, and lastly- run the vehicle at least half an hour before testing.
Good luck!
Hotshot
Joined: Oct 2002
Posts: 18,488
Likes: 22
From: The Big, Oregon
Help passing the sniffer!
Lean the idle about 1turn, up the timing, and set the idle to about 750-800rpm. Also, change the oil. If your truck was running that rich, the oil is more than likely diluted, causing more hydrocarbons to spew from the exhaust. Also, check the float level.
Post Fiend
Joined: Nov 2002
Posts: 9,987
Likes: 7
From: Memphis, TN
Help passing the sniffer!
DON'T turn the engine off while you're waiting. That's the biggest reason for failure. In fact, hold it at a high rev for a few minutes (yes, minutes) just before you pull in so everything is plenty hot.
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