oil viscosity emissions question
05-05-2003, 06:46 PM
#1
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oil viscosity emissions question
does thicker oil produce more HC or thinner oil?
i failed my emissions and i want to know if i switch oils it can drop my HC slightly.
i failed my emissions and i want to know if i switch oils it can drop my HC slightly.
05-05-2003, 07:13 PM
#2
what are your readings? Use the oil the keeps the lifters happy.
I need to see your values to let you know if your HC's are a result of misfire or richfire - hmmm new word 
Also, old oil due to blow by may be soaked with fuel which causes high HC's. My experience is synthetic seems to be better (due to oil vapor going back into the engine)
Also, old oil due to blow by may be soaked with fuel which causes high HC's. My experience is synthetic seems to be better (due to oil vapor going back into the engine)
05-05-2003, 07:14 PM
#3
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Do not think so, try changing fuel and/or cleaning fuel system.
Fuel may have problems burning properly due to its composition (crappy fuel) or lack of proper atomization (fuel injectors leaking or failing to spray in a fine mist).
I have also seen off the shelf fuel additive products specifically designed to help you pass emissions testing.
What percent do you need to decrease HC's?
Fitch fuel catalyst can drop them slightly. I have used it for over a year (maybe two), and it has worked absolutely great--perfect combustion based on spark plug condition. Basically, it adds nothing to your fuel, it just changes the length of the fuel molecules combining shorter ones into longer ones and breaking up the ones that have become too long (double linked). Overly short molecules pre-ignite and overly long molecules may not burn at all.<ul><li><a href="http://www.fitchfuelcatalyst.com">Click here</a></li></ul>
I have also seen off the shelf fuel additive products specifically designed to help you pass emissions testing.
What percent do you need to decrease HC's?
Fitch fuel catalyst can drop them slightly. I have used it for over a year (maybe two), and it has worked absolutely great--perfect combustion based on spark plug condition. Basically, it adds nothing to your fuel, it just changes the length of the fuel molecules combining shorter ones into longer ones and breaking up the ones that have become too long (double linked). Overly short molecules pre-ignite and overly long molecules may not burn at all.<ul><li><a href="http://www.fitchfuelcatalyst.com">Click here</a></li></ul>
05-05-2003, 11:55 PM
#6
Your problem is NOx not HC or CO, although your CO is a bit high which can increase your HC...
But deal with the NOx first.
First thing, I don't know what your 272 cams do for you at emissions testing. Did you have them 2 years ago when it passed? If not, what is you idle vacuum reading right now? Does the car idle smooth? If not, then that could explain higher HC. Also, NOx is reduced with valve overlap. Eliminating that via more aggressive cams means you have to solely rely on the EGR valve. More on this below
NOx is strictly nitrogen combining with oxygen because combustion temperatures where so high.
The oxygen comes from excess when the engine is running optimal A/F ratios. Increased temperature is due to many factors. High compression either by design or carbon buidup. Advanced ignition timing (from specs), an engine running too hot (oil and water temps too high). A lean mixture also increases combustion temps, which starts to increase NOx formation, but at the same time, lean causes misfire which means raw fuel and air (as opposed to excessive 02 from complete combustion) is dumped, so HC's increase more so than NOx. Plus your CO readings don't look anywhere lean. What rpms are those run anyway? I'm assuming cruising rpms and not idle. Was the car under load during the test? They don't do that yet on California (nor use a 5 gas breather - HC, CO, CO2, 02 and NOx)
Does your EGR work? Do you know how to test it? The EGR's main purpose is to feed inert gas in the chamber to lower temperature because the volume of combustible misture is reduced (including power). Inert gas is residual exhaust gas after ignition happens. Hence why I mentioned valve overlap. Take it away and the only way to fill it back in is through the EGR. This means if the cams are modified, the EGR may need to be modified to compensate (make it's ports bigger).
Other things - what is your timing now? Is 18 or 15 close to stock? I'm too lazy to look. If not, put it back to stock. Notice your NOx went down when it was retarded?
How's your thermostat? temperature readings normal? water pump working? Oil temps look good? too old of an oil or too thick or too thin may increase oil temps
Of course we can't forget your cat. You mention it is only 20k miles old. A cat is really good at reducing NOx down (since that's intentionally what a 3 way cat was designed to do) You do have a 3 way cat right? A two way only breaks down exessive CO. Rich CO's can overburden a cat and prevent it from cleaning up NOx properly also.
Check your O2 sensor to make sure it is working properly to keep the CO's in check. Check you plugs and wires to keep HC's in check.
First thing, I don't know what your 272 cams do for you at emissions testing. Did you have them 2 years ago when it passed? If not, what is you idle vacuum reading right now? Does the car idle smooth? If not, then that could explain higher HC. Also, NOx is reduced with valve overlap. Eliminating that via more aggressive cams means you have to solely rely on the EGR valve. More on this below
NOx is strictly nitrogen combining with oxygen because combustion temperatures where so high.
The oxygen comes from excess when the engine is running optimal A/F ratios. Increased temperature is due to many factors. High compression either by design or carbon buidup. Advanced ignition timing (from specs), an engine running too hot (oil and water temps too high). A lean mixture also increases combustion temps, which starts to increase NOx formation, but at the same time, lean causes misfire which means raw fuel and air (as opposed to excessive 02 from complete combustion) is dumped, so HC's increase more so than NOx. Plus your CO readings don't look anywhere lean. What rpms are those run anyway? I'm assuming cruising rpms and not idle. Was the car under load during the test? They don't do that yet on California (nor use a 5 gas breather - HC, CO, CO2, 02 and NOx)
Does your EGR work? Do you know how to test it? The EGR's main purpose is to feed inert gas in the chamber to lower temperature because the volume of combustible misture is reduced (including power). Inert gas is residual exhaust gas after ignition happens. Hence why I mentioned valve overlap. Take it away and the only way to fill it back in is through the EGR. This means if the cams are modified, the EGR may need to be modified to compensate (make it's ports bigger).
Other things - what is your timing now? Is 18 or 15 close to stock? I'm too lazy to look. If not, put it back to stock. Notice your NOx went down when it was retarded?
How's your thermostat? temperature readings normal? water pump working? Oil temps look good? too old of an oil or too thick or too thin may increase oil temps
Of course we can't forget your cat. You mention it is only 20k miles old. A cat is really good at reducing NOx down (since that's intentionally what a 3 way cat was designed to do) You do have a 3 way cat right? A two way only breaks down exessive CO. Rich CO's can overburden a cat and prevent it from cleaning up NOx properly also.
Check your O2 sensor to make sure it is working properly to keep the CO's in check. Check you plugs and wires to keep HC's in check.
05-06-2003, 06:29 PM
#7
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NOx problem: I would change spark plugs in addition to what Audiboy said . . .
If you lower combustion chamber temps, you should see fewer NOx's.
#1: check your EGR valve; it exists solely to solve the NOx problem.
A couple of additional ways, (1) richer fuel mixture (increase fuel pressure with adjustible FPR if you have one); (2) cooler plugs to absorb more heat and cool down the combustion chamber (that's 70-100 degrees right there).
Good Luck!
#1: check your EGR valve; it exists solely to solve the NOx problem.
A couple of additional ways, (1) richer fuel mixture (increase fuel pressure with adjustible FPR if you have one); (2) cooler plugs to absorb more heat and cool down the combustion chamber (that's 70-100 degrees right there).
Good Luck!
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