W126 FAILED Emissions Test!

[drosen]

I bought this 1990 300SEL that had been sitting parked for over 2 years.
As part of getting it in shape over the last 2 months I changed the oil & filter (twice), replaced the fuel filter, and it is on its 3rd tank of fresh premium gas.
Each time, I poured a bottle of fuel system cleaner in the gas tank when I was filling up with gas.

The car idles nice and seems to run strong, so I took it for the emissions test. It failed.
Hydrocarbons 1.4136 GPM (maximum allowed is 1.4000) and
Oxides of Nitrogen 2.7471 GPM (maximum allowed is 2.5000).

1. Is it possible that the oxygen sensor is bad even though the car runs nice and the check engine light never comes on ?

2. Is there some heavy duty stuff I should pour or spray directly somewhere to get rid of built up carbon or other junk?

3. I purposefully didn't change the spark plugs yet because if I need to run some heavy duty stuff through the car I wanted to have it foul the existing plugs and THEN change to nice clean plugs. I didn't think changing the plugs yet would make much difference in the emissions since the car runs well - am I wrong about that? Can changing the plugs reduce the emissions that much?

Any help much appreciated, especially with step by step directions that a moron can follow.

Thank you.

[KarTek]

Contrary to popular belief, regular gas is preferable to get you over the top on an emissions test due to it burning easier than premium. Also, make sure the car is good and HOT before testing. This is kind of a moot point if your state does load testing but more important if you have to wait in line for a static test. Try picking a time when there's no line. Another thing I've done is to put a piece of cardboard infront of the radiator so that the temp gauge runs steady a little higher than normal.

Changing the plugs is a good idea because worn plugs can effect combustion. If the plugs aren't that old, make sure they're gapped properly. If they were run at all with older gas they can be fouled to some extent.

I went through this time and time again with my old white truck. It was always just over the limit. Finally, they did away with emissions testing for non-OBDII vehicles...

[johnjzjz]

run out the tank of fuel you now have real empty than re fill it BUT add
( Acetone ) 2 oz per 10 gallons of fuel is the most you want to use, it drastically reduces the surface tension. Most fuel molecules are sluggish with respect to their natural frequency. Acetone has an inherent molecular vibration that "stirs up" the fuel molecules, to break the surface tension. This results in a more complete vaporization with other factors remaining the same. More complete vaporization means less wasted fuel, hence the increased gas mileage from the increased thermal efficiency. and lower emissions --- please NOTE you must use the stuff they use on girls nails for removing the polish - wallgreens sells a small bottle has to say 100% pure ( the industry type stuff ( home depot ) does not work ) and its the reason some mope will tell you it does not do what i have written --
That excess fuel was formerly wasted past the rings or sent out the tailpipe will now be mixed with acetone it gets burned, though the engine still thinks it is running straight gas. as well as the test equiptment testing the engine --
i have used it for almost 10 years now my 2003 duramax diesel has over 100,000 with no ill at all -- in my shop in jersey we have small problems like yours all the time and its what we do, it almost never not fixes a small problem like yours -- it wont fix a bad or dead cylinder but will reduce the emissions in almost any engine - jz

[KarTek]

Originally Posted by johnjzjz

please NOTE you must use the stuff they use on girls nails for removing the polish - wallgreens sells a small bottle has to say 100% pure ( the industry type stuff ( home depot ) does not work ) and its the reason some mope will tell you it does not do what i have written --

That's interesting there. I did try the stuff from HD and it did absolutely nothing in my truck... Hmmmm...

[johnjzjz]

Originally Posted by KarTek

That's interesting there. I did try the stuff from HD and it did absolutely nothing in my truck... Hmmmm...

HI my 1990 305 5 speed stick 2500 chevy would not clime up hills with the air on with out downshifting it had 200,000 miles on it, than we started to use the acetone and it got 1 to 2 better MPG and over all it ran better when i forgot to put it in within 2 tanks of gas i thought their was something wrong with it. then i remembered sold it to a friend 3 / 4 years ago and its still going - jz

beauty supply places sell gallons its what i buy there is a difference

[drosen]

Thanks so much for the tips.
Not what I was expecting to hear, but I appreciate everything people tell me that I can learn.