Does anyone know the effect of adding oxygenates such as MTBE to gasoline in terms of exhust emission testing. In winter time many parts of the US have to switch or add oxygenates to gasoline. I am wondering what effect that has when you take your car for emission testing. This is an interest to me since my car 92 400E just failed the HC part of the emission test (102 limit is 100).
Does make sense to store some gasoline from summer time then put it in the car before going for emission testing?

Rafi,

It is my recollection that the oxygenated fuel will yield better emmissions which is the whole reason that they require its use during the winter. Cold weather makes the engine more polluting, especially during the warm up period - which of course is longer in January than July - adding the oxygenating additives helps to counterbalence this.

You will notice poorer fuel economy as measured in miles per gallon however since less of what goes into your tank is the actual fuel that powers the car. You're also getting some oxidants which during the summer come entirely from the air.

jlc

__________________
Jeff

'87 560SEL 267K (177K on motor) Blue/Blue
'98 Buick LeSebre 60K (wife's car)
'56 Imperial Sedan 124K
Past Cars:
'67 Dodge Monaco 130K (Sold)
'87 Chrysler 5th Ave 245K and going strong (sold)
'73 Plymouth Satillite 175K (sold)
'96 Chrysler LHS 80K (totaled)

Heres a link www.eps.gov/mtbe/ that helps to explain.

Also, as a comment, here in the cesspool city of missouri, they use MTBE in the winter and I get 2-5 mpg LESS than with regular formulated gasoline. So I wonder... milage is less,therefore more gasoline is burned= more emissions. Even if a vehicle emits less pollutants with mtbe gas per volume burned, does the overall decrease in emissions balance out? I dont think anybody knows.

That link doesnt work, got to www.epa.gov and search for "mtbe", then click on what may be the second choice, www.epa.gov/airlinks/airlinks6.html, then clikc on the highlighted "methyl teriary-butyl ether"

inspector1 - I think they know all effects they only release enough skewed information to justify/coerse certain behaviour they want from us.

Oh yeah, using old gas is a bad idea

I agree, also is tied in with major chemical companies, as is cited in the web page, over 200,000 barrels of mtbe is distilled each year, thats, lets see 200K times 55 gallons per barrel=11 million gallons, ker-ching!,ker-ching! for DOW chemical.

Down in southeastern Mo mtbe is in alot of the ground water and it is a known carcinogen and other serious health effects.

inspector1 - why is using gasoline from summer without the oxygenates a bad idea?

Yes, I have noticed too that in the winter the gas milage goes down. It is consistent, since oxygenated fules are partially oxidized or burned so they do not have the same caloric energy as plain hydrocarbon, therfore you use more fuel. Now if you use more fuel does the HC emmision go up?

I did go to the EPA website and all I could find is oxygenates is used to reduce CO emmision in winter time. I could not find the effect of oxygenates on other emissions such as HC or NOx. My car's CO emmision is 0.28 for max of 0.50 it is well below the limit. If oxygenates increase HC emission then certainly reducing the oxygenates content in gasoline will have the right effect for my situation.

This is backwards, oxygenates are supposed to help combustion go to completion, decreasing HC emissions for X volume.

California has banned the MTBE additive. They have found it in ground water and it will not naturally decompose.

Haasman

__________________
'03 E320 Wagon-Sold
'95 E320 Wagon-Went to Ex
'93 190E 2.6-Wrecked
'91 300E-Went to Ex
'65 911 Coupe (#302580)

MBTE is being phased out nationwide. Everyone knew the stuff was water soluble when it was implemented, but the idiots went ahead with it anyways. Clean air at any cost, right?

Here's the deal:
Oxygenated fuels contain less energy.

Cars with modern sophisticated feedback induction systems simply inject more fuel to compensate for the air/fuel ratio change.
Cars with primitive carbs may pollute somewhat less due to a leaner mixture. The cooler winter air is more dense, so the mixture is getting 'optimized' with oxygenated fuels (in a crude way).

Since 'dumb' carbs are becoming rare, the whole matter is rather silly, and very costly to implement in the supply chain.

Now the mandated additive is polluting our drinking water. What will that cost? Regulatory meddling at its finest...

Anyways, there should be near zero difference in your emissions test. Just make sure the motor is fully warmed up so that the cat is hot, which is a seasonal factor to some extent.

__________________
1986 300E 5-Speed 240k mi.