How to cheat emmissions 101! Hopefully
Registered User
Joined: Jan 2002
Posts: 134
From: culleoka, tn. 38451
heres what happens is you get whats called dilution. what do you think that gas analyzer is measuring? how loud yer car is? without giving away the store here-co, o2, co2, and hc to a lesser extent (we will leave nox out of the picture for simplicitys sake)are all byproducts of combustion, most smog techs as well as the analyzer that your car is hooked to for the test know for sure how much of one gas begets how much of the next and if the previous 2 gas readings are such and such what the 3rd gas should look like, its simple physics, all the gas ratios are related to the other in the brew. so here comes clem with a big ole compressed air tank rube goldberged into his exhaust(some of the stuff that gets posted on this board is, well, um, lets say astounding) 
and clem has his cousinsbrotherssistersunclemother "hit" or is that "heeeeat" the switch and inject "air" "o2" or whatever, dontcha think that when the residual o2 gets to be 10% or so that the analyzer will abort the test, cuz to have 10 % residual o2 mother nature says something aint burning right. so dilution is too much oxygen in the exhaust stream, flags an abort and take it from there, same with a exhaust leak exhaust gas out air in=dilution.
and clem has his cousinsbrotherssistersunclemother "hit" or is that "heeeeat" the switch and inject "air" "o2" or whatever, dontcha think that when the residual o2 gets to be 10% or so that the analyzer will abort the test, cuz to have 10 % residual o2 mother nature says something aint burning right. so dilution is too much oxygen in the exhaust stream, flags an abort and take it from there, same with a exhaust leak exhaust gas out air in=dilution.
Registered User
Joined: Mar 2001
Posts: 956
From: Winston Salem, NC
lets hear it for South Carolina 
Have you tried all the standard tricks? Drive the car around for an hour letting it get real hot before the test, change the oil, throw some of that guaranteed to pass emissions stuff at the auto parts store in the tank, and above all make sure your car is running right! Everything in the world you do isn't going to work if you have a miss somewhere...
Have you tried all the standard tricks? Drive the car around for an hour letting it get real hot before the test, change the oil, throw some of that guaranteed to pass emissions stuff at the auto parts store in the tank, and above all make sure your car is running right! Everything in the world you do isn't going to work if you have a miss somewhere...
Administrator
Joined: Nov 1998
Posts: 71,094
From: Hell was full so they sent me to NJ
If you're failing for NOx, its likely the engine is running too hot, and too lean. Those are the conditions that promote oxides of nitrogen. Is your EGR system still connected? That reduces NOx.
Adding "air" to the exhaust might have a remote chance of reducing HC and CO.... they require "oxidation" to reduce the quantity. But NOx forms because there is too much "air".... so it is unlikely that adding air to the exhaust will do anything other than cause an un-natural level of O2 in the exhaust, as noted in the post above.
Be interesting to see how this works out......
Adding "air" to the exhaust might have a remote chance of reducing HC and CO.... they require "oxidation" to reduce the quantity. But NOx forms because there is too much "air".... so it is unlikely that adding air to the exhaust will do anything other than cause an un-natural level of O2 in the exhaust, as noted in the post above.
Be interesting to see how this works out......
Registered User
Joined: Jan 2002
Posts: 134
From: culleoka, tn. 38451
not to pick nits but nox is a byproduct of heat and high combustion pressures, emission control systems as seen on modern computer controlled cars like combustion chamber temp to be as close to 2000 degrees farenheit as possible. 2500 degrees brings on a very sharp increase in nox formation. hence reverse cooling and aluminum heads. believe me that the boys at gm designing these motors were not just looking for max power, emission output levels obviously were taken into account too. but its funny how an engine design that concerns itself with emission output invariably makes good efficient power too. (meaning any motor designed during the computer controlled, fuel injected era we are in now, not some funky 307 olds motor with a ccc or c4 system calling the shots) i like my cake, and i get to eat it as well.
Registered User
Joined: Jun 2002
Posts: 1,817
From: O-Town
Originally posted by Injuneer
If you're failing for NOx, its likely the engine is running too hot, and too lean. Those are the conditions that promote oxides of nitrogen. Is your EGR system still connected? That reduces NOx.
Adding "air" to the exhaust might have a remote chance of reducing HC and CO.... they require "oxidation" to reduce the quantity. But NOx forms because there is too much "air".... so it is unlikely that adding air to the exhaust will do anything other than cause an un-natural level of O2 in the exhaust, as noted in the post above.
Be interesting to see how this works out......
If you're failing for NOx, its likely the engine is running too hot, and too lean. Those are the conditions that promote oxides of nitrogen. Is your EGR system still connected? That reduces NOx.
Adding "air" to the exhaust might have a remote chance of reducing HC and CO.... they require "oxidation" to reduce the quantity. But NOx forms because there is too much "air".... so it is unlikely that adding air to the exhaust will do anything other than cause an un-natural level of O2 in the exhaust, as noted in the post above.
Be interesting to see how this works out......
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