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Emission on steriods?

What’s the rub on the emission cure in a bottle that’s sold in all the autoparts stores? Is it 21st century snake oil or is there something to it?


Could you as a service to the readers of this Forum purchase this product and use it in your own “failed emissions test car” and give us a report from a person who has actually used the product?

I would love to but I already got the fix that I needed and passed but I did consider trying it beforehand and just thought to ask about it for future reference. Hopefully, someone else has used it already and can let us both know.

I could use some time in a parts store so I hope to get a good read in tomorrow. I still won’t know anything but the wording might be fun.

If it is failing due to neglected maintenance, it may just work. If it is due to a mechanical failure, it will not work. No bottle treatment will fix a broken EGR or burned out catalytic converter. Or vacuum leak. Or bad fuel pressure regulator. Or broken etc etc etc.

People never admit to buying this kind of stuff,no one wants it to be known they were so easliy conned,just for future reference.

There is no miracle cure. If the emissions failure is due to a dirty injector is could possibly help, but emissions failures can occur for a huge variety of reasons, none of which can be helped by an additive.

A few are
worn ignition components
overly dirty filters
a bad oxygen sensor
a bad (inefficient) cat converter
a carboned-up or inoperative EGR valve
fuel pressure problems (typically caused by the pump or regulator)
worn injectors (as opposed to the proviously mentioned dirty injectors)
a worn out engine (burning oil om particular)
an EVAP system problem. Including a plugged up carbon canister preventing proper fuel delivery via a vacuum in the tank.
inaccurate ignition timeing, especially in distributor based ignition systems

And, if your state does OBD downloads add a few hundred more possible causes.

None of the above can be fixed by an additive in a bottle.

Since I have no pride, I will admit to having bought a can of that stuff once. I don’t recall the brand, but the car was a 20-year-old Volvo with 300k miles and the original catalytic converter. Come to think of it, that car had almost everything original. It just barely failed smog for both NOx and CO, and I knew the air filter was clean, plugs were fresh, MAF and throttle body were clean, hot air intake was disabled, no major vacuum leaks. Was not sure what to try that was not expensive, so I tried a can of magic juice to see if it would help. No effect at all.

P.S. although the can says “Your money back if you don’t pass” I did not bother. I expect that the manufacturer counts on most people not going to the trouble to get their money back.