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Make sure your catalytic converter is plenty hot when you get it checked. 15 minutes of highway driving is good. You need to be running gas that has had the max amount of ethanol and/or MTBE added- not premium. I agree that it is running too rich. Since you have a carb this is a pretty easy thing to fix with a meter and a screwdriver- 1/2 hour shop time and it will increase your mileage greatly as well. Basically, your car needs a carb and timing adjustment (1 hour shop time) before a new cc. Even if that doesn't fix the problem (it will) it will pay for itself in increased gas mileage. Oh, and air up your tires too.
Craig
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[quote macone]
My suggestion comes from real world dyno testing not surfing the net. Speaking of which, either you left something out or you didn't copy and paste enough in your mixture adjustment procedure or are you suggesting that he tells his mechanic what to do?
Was it your own dyno testing? How many engines were tested? US, Japanese, German, and what was the range of compression ratios? EFI and carb? What year cars? Stock or modified? Pre or post tune up? What brands of gas? Winter or Summer fuel? What State and what was the percentage of oxygenate?
Given that the NOx and O2 were low, Premium would do little to help his problem since the car was running rich from what I can see on the test. IF the ONLY problem was high NOx, and it was a car with a compression ratio over 10, then it might help.
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Heck, it has been a long time since I tuned a carb system. One thing I recall, not yet mentioned, that would push the mixture slightly rich at closed to partial throttle was a build up of varnish in the throat. The coating would restrict air flow just a bit until the throttle plate opened wider. A cleaning would take that out as a possibility.
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More than you have done on the internet. The mix was German, English(some with American engines), & Italian. Carb & Fuel Injected. One brand of gas. 3 types of fuels. 87,91, Racing. Various mixtures of gas and other products. All fuels tested within a 2 hour time frame with the car at the roughly the same operating temperature. Cars were set up to run on external fuel pumps that matched the cars fuel pressure requirements. Fuel was provided from individual containers. Cars were run until they ran out of the type of gas tested. Summer Mix. Of the non mixed fuels, premium consistantly had the lowest overall emissions. We simulated the California test method on the dyno.
Strange, before you, say do not use premium. Now you say it wouldn't make a difference in this case. In the original post, the poster mentions he used Premium. So how do you know what was or wasn't affected?
You can now return to your internet surfing.
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Car passed smog. But just barely. Dont think the Cat Convertor changed anything. The o2 are low, but the HC is 133 and just barely passed the 134 level, needed to pass. Did get the cheap cat converter and drove it 10 miles on the freeway before test. So I need to get the HC down. Sounds like a Carb adjustment and timing would be relatively easy and harmless.
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[quote macone]More than you have done on the internet. The mix was German, English(some with American engines), & Italian. Carb & Fuel Injected. One brand of gas. 3 types of fuels. 87,91, Racing. Various mixtures of gas and other products. All fuels tested within a 2 hour time frame with the car at the roughly the same operating temperature. Cars were set up to run on external fuel pumps that matched the cars fuel pressure requirements. Fuel was provided from individual containers. Cars were run until they ran out of the type of gas tested. Summer Mix. Of the non mixed fuels, premium consistantly had the lowest overall emissions. We simulated the California test method on the dyno.
Strange, before you, say do not use premium. Now you say it wouldn't make a difference in this case. In the original post, the poster mentions he used Premium. So how do you know what was or wasn't affected?
You can now return to your internet surfing.
You left off compression specs of the engines and if the manufacturers had specified that they should be run with Premium. I would also like to know if they were originally sold as cars designed to pass CA emission standards.
Just to make it clear, I first saw studies recommending not using Premium in engines not designed for it before most people were on the internet. This was prior to 1992. I stand by the recommendation. For most people with cars not designed to run on Premium, it should not significantly improve emissions as long as the car is running properly.
Microman most likely has a car with a 9.5:1 compression ratio based on the year and lack of EFI. The numbers on the emission test seem to indicate that it is running rich (assuming they are accurate). If his car failed due to high NOx but the HC and CO numbers were low, then I would recommend trying Premium as one quick option to try.
I currently have a car with a 10.0:1 compression ratio and the manufacturer recommends Premium. That is what I use almost exclusively. When gas prices went over $3.50, I tried two tanks of Unleaded. I found that I got very slightly lower mileage and seemed to lose a few HP at full throttle.
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[quote Filliam H. Muffman]
You left off compression specs of the engines and if the manufacturers had specified that they should be run with Premium. I would also like to know if they were originally sold as cars designed to pass CA emission standards.
Just to make it clear, I first saw studies recommending not using Premium in engines not designed for it before most people were on the internet. This was prior to 1992. I stand by the recommendation. For most people with cars not designed to run on Premium, it should not significantly improve emissions as long as the car is running properly.
Microman most likely has a car with a 9.5:1 compression ratio based on the year and lack of EFI. The numbers on the emission test seem to indicate that it is running rich (assuming they are accurate). If his car failed due to high NOx but the HC and CO numbers were low, then I would recommend trying Premium as one quick option to try.
I currently have a car with a 10.0:1 compression ratio and the manufacturer recommends Premium. That is what I use almost exclusively. When gas prices went over $3.50, I tried two tanks of Unleaded. I found that I got very slightly lower mileage and seemed to lose a few HP at full throttle.
Are you for real? I don't care what you stand by or for. I'll stick to my REAL WORLD data.
Everything you posted is easily derived from the net. There are websites that have references on how to read smog results. So your proclamation that is running rich is not exactly earth shattering.
My one mistake was leaving my Nox statement, It was actually supporting another sentence which I deleted.
Your funny. You put regular in a car that recommends premium. Where you really surprised it made a difference and one for the worst? Your idea of real world testing?
I have been a lurker on this forum for awhile. I usually ignore the misinformation I read about cars. You can tell which ones are the posers. The ones that do either a google or wikipedia search and then feel they are now experts. Then post. ( Actually seen this on many different subjects.) See any resemblance? For you, should I add magazines from 1992?
There is one poster on this forum that I believe that actually posts from experience about cars. From what I gather he used to work in the trenches at a GM dealership. If he is not for real he has me fooled. I don't always agree with his opinions about cars but I respect his opinion. I noticed he was much smarter than me and didn't post to this thread.
I only posted because Microman test results were so close to passing. I felt he was on the right track with the premium. Premium isn't going to make a gross polluter pass but it can make the difference between pass/fail and wanted to discourage him from removing it.
I believe this horse is dead............But, I maybe wrong.
