Rubbing Alcohol To Pass Smog



Myths or Truth?

I have heard that adding about 1 1/2 oz. of rubbing alcohol/gallon will help in smog test. Also, it was suggested that the wastegate rod be disconnected before testing.

Can alcohol reduce O2, HC, and NOX emissions and, if so, will adding it damage O2 sensor?

How would disconnecting the wastegate rod help pass the test? Is this the rod under the front of the turbo?




Active Member
I use Denatured Alcohol...not Rubbing...does it work...who knows?...but I haven't failed yet using I figure it can't hurt...


intercooled engines rule!
taking off the wastegate rod will not let the turbo boost and not comanding more fuel. just dont get on it going to the test. and if you have any aftermarket gauges disable them and cover them, the kids like to watch the gauges rather than looking at the test screen.


Active Member
Alcohols (rubbing, methanol, ethanol, denatured, etc.) will not hurt the O2 sensor. The driver shouldn't make boost during the test anyway, so in theory taking off the rod won't make a difference. However, some around here like driving in digital mode, stomp gas until going too fast, then lift completely until too slow, then repeat :). In that case taking off the rod may help some, but may not help enough. That's why I like to have the laptop with DirectScan (or Turbolink) recording (set DS to 4 frames/sec or slower so it will get the entire test) while the car is on the dyno, and I tell them all about how it is recording all the sensors, including the tps, so I can tell if they are doing an acceptable job of driving so if I fail I can show their boss. I also tell them before they turn the key on to mash the gas pedal a few times, then to rev it up once or twice in neutral, so they can get the feel of the car - I want the smoothest test I can get.

Will alcohol lower emissions? Maybe, especially if you are running too rich. How much to add? Dunno.


Certifiable Member
One thing you guys should know... Alcohol is corrossive, Make sure you add alky to a very low tank of fuel, like under a 1/4 I added a whole gallon and I got through a test without a Cat (hollow) you must go fill your tank right away, because the alky will corrode your fuel system, might not hurt anything but probably would if you left a high concentration in your tank during winter storage.....

p.s. run some boost with your alky gas mixture and see how well it works...:biggrin:


Staff member
I wouldnt use rubbing alky unless it was nearly 100% alky. The stuff you buy at a store is a max of 91%. The other 9% is water:eek: . From my experiences with methanol, it will lower the CO if you can get the block learn out of its correction window. Basically it will stay at 150 when out of its correction window. Then the correction is maxed out and anything further you do to lean it out will work. If you fail on HC you may have other issues. It will take a lot more than the amount that was suggested to you. You will need 20-30%. Dont forget that most gas in the USA has up to 10% ethanol already. Our fuel systems are very resistant to corrosion from alky.


1 sec reaction King
Pep boys carries a product called G2P- Guarunteed to Pass. Its a few bucks for a bottle. Never failed using this stuff.

Race Lutz

New Member
The first thing you need to do to pass emissions is to change the oil. You will have a large collection of burned gasoline and oil by-products in the motor oil. So, that's the first thing you do.

Next, make darn sure all your filters are in really good shape. That's air and oil filters, both.

Next, make sure your ignition system, including the wires and spark plugs are good.

Get the gasoline low in your tank and make sure it is good gasoline. Then, add to your tank, the off the counter stuff from Pep Boys. (Forgot the name.)

To make sure you can use some gasoline moisture remover to your tank. I use "HEET."

The three things that will cause the most problems are: Spark plugs, motor oil and filters.

Good luck!

Boy Buick85

Well on mine every thing looked good except the Nox (SINCE I HAVE NO CAT:biggrin: ) So will the g2p stuff do the same as the alky or what ?????


Active Member
your NOX is high because you either have a faulty or inoperative AIR system, or timing that is too far advanced. NOX is formed by extreme temperatures which AIR and retarded timing work to reduce.

a cat would probably produce more nox


Active Member
What chi[ are you running now? does it disable the egr? if so get an emissions chip burned for your size injectors. My NoX's were high on my GN when I had a hollow cat, I put a new cat on and passed with flying colors.