What's a "Mexican tune-up"?

From this thread.

Clearly derogatory, but I’m unfamiliar with it. Googling didn’t help.

I believe the original usage is an “Italian tune up”. It refers to filling up the gas tank and/or crankcase with some sort of solvent (kerosene in the version I’ve heard) and driving at top speed on the highway (or autostrada) for a long period of time. Supposedly this would clear carbon deposits from the engine.

During the days of non-detergent oil, engines had to be periodically disassembled and cleaned and since an “Italian tune up” was seen as a lazy work-around to this, that might explain why it’s morphed into an “(insert ethnic group here) tune up”. According to the entirely cite-free wikipedia article, there actually was some basis in it being “Italian” originally: Italian tuneup - Wikipedia

With the engine running, inject a bit of water into the intake. Steam cleans the carbon out of the cylinders. Allegedly.

Probably best to do this with a carbureted engine rather than fuel injected. Because I suspect trouble will ensue.

It means taking the car out onto the highway and stomping on the gas to blow the carbon out of the engine.

It’s also called a “poor man’s tune-up”.

The Urban Dictionary also lists “Italian tune-up” to mean the same thing. I have personally heard the Mexican version more than the Italian version, but YMMV.

I’m seeing regional variants on slang here…

Anything’s better than the “Youngstown tune-up,” in which your car explodes upon ignition.

When I was growing up in Chicago, a Polish tune-up was similar, but rather than “drive it like you stole it” freeway driving, it involved annoying the neighbors with repeated pedal to the floor revving while parked.

The intent was the same - get the “junk” out of the cylinders without doing any actual repair work.

Ok, I guess the next question is:

Does any of this actually help engine performance?

On modern cars, no (with a handful of exceptions). An up-to-date equivalent, more likely to be helpful, is to add a fuel system cleaner (Techron is best) to the gas tank a few times a year.

If the car has been driven “grandma style” for a long time an Italian tuneup does do wonders. I’ve done a few of these and when you floor it an impressive amount of black smoke comes out the tailpipe. Afterwards the engines ran noticeably smoother. This, BTW, was on both older carburated and newer EFI cars.

The “proper procedure” is to first drive it on the highway for 20 minutes or so to get everything nice and toasty, slow down to an almost stop, down shift, and floor it as long as you have the nerve. Repeat until you see no more smoke in the mirrors.

The modern usage seems to be SEAFOAM

I see what you did there.

And here in Mexico, I’ve heard people call that process “quitarle el burro” (get rid of the stubborness or laziness is how I seem to interpret this), which is something I do to my father-in-law’s Caddy CTS every year. It’s a fully modern MY2003, and driven like an old man’s car by an old man: 30,000 km in seven years. I take it easy for a while, and then hit it hard (i.e., drive it like it’s mine). There’s some black gunk a few times, and then the engine seems to run a lot smoother. It does work.

It used to be a common term among VW Beetle owners. If the engine was running rough, you took off the air cleaner, revved the engine by pulling on the throttle cable, then blocked the top of the carburetor with your hand, which caused a vacuum in the intake manifold and sucked the dirt out of the jets. Sometimes it actually worked, sometimes you got a backfire and scorched your hand. I live at the end of a dusty dirt road, so I give it a try every couple of months.

Never done it but have heard of sprinkling rice kernels into the intake to remove carbon, also heard about water, again never done it.

I know of a factory service bulletin that to cure rough idle / misfire at idle instructed the technician to change the oil to synthetic, and then drive the car for 10 minutes at 5,000-6,000 RPM.
It seems the valve did not rotate at engine speeds under 4,000 rpm and if the car was driven like a little old lady owned it the valves would leak and cause problem.
Flogging the crap out of it cured the condition.
They called it (informally) a Kentucky tune up.