l have a 87 Porsche 9442.5L and l know its got a very severe carbon build up. Example I am driving along in traffic and suddenly without warning it coughs and looses all power. It idles fine and doens't over heat. It there anything that would really work. I've already used Techron and othersbut l have a feeling what l have needs soemthing extra strength. Are there any additives that work to eliminate a lot of carbon quickly without actually taking the whole engine apart?

run a regiment of stp fuel injection cleaner

introduce water in carb/throttle body from a spray bottle at slight rev or remove head and do it manually

DO NOT put water in a fuel injected car. It is not good for it at all. An alternative would be rubbing alcohol, since it will burn very cleanly & will clean the engine much better than water. but make sure it is a very small amount sprayed with a mister into the open throttle body.

Run a bottle of fuel injector cleaner with a tank full of hi octane fuel from a good gas station, like shell.

If u r still having problems, u may want to change the fuel filter, or check the Mass air flow sensor & or EGR valve, a problem with these would also cause the problem u described.

If you have a Porsche with carbon buildup.you are not drivin' it right !!!!! Mash it.Drive it like you stole it for GD is sakes! :-)

: put in combustion chamber cleaner and dog it..hey, its advice from a mechanic.

First you remove all of the spark plugs put quantity of REDX in to plug holes leave over night next day cover plug holes with a cloth and catch the RED-X that is pushed out when you spin over engine replace sparkplugs start engine up wait for smoke to recede might take 5 to 10 min. uk driver

Does the car 'run on' after u turn off the ignition? Parked & with the engine running & transmission in neutral, turn off the key. Do nothing else. You should perform this test after running the car long enough to warm it well. Does the engine quit running immediately, or does it kind of sputter on for a while, coughing & wheezing? Note that it wo not run very long this way with fuel injection; older carburated cars could sometimes keep going on their own for minutes. A severe carbon build up will act like the glow plug of a diesel engine; it does not need the electric spark to keep igniting the fuel & turning the engine over.

If it does not do this, it is likely the problem is something else, or at least more complicated than just carbon build up. Take it to a dealership.

There is some merit in the alcohol method, but I'd be afraid to try it myself -- alcohol burns with a virtually invisible flame & it is best to keep it away from all sources of ignition.

I've also got to agree with the idea that the car is not being driven hard enough. This happens a lot with Porsches that people keep as 'garage queens.' If u have not got any other problems you're worried about, try taking the car out on a local track (always obey all local & national speed limits :) ) & ''blowing it out.'' Just touching red line wo not kill it, particularly if you've got a rev limiter on the vehicle. DO NOT blow ur engine by running over the red line on the tachometer. NOTE that a single turn around an oval is not going to get the job done.

Chevron Techron is pretty good, and l do recommend it for normal buildup, but if you really want to clean your engine out, try Lubro Molly Ventil Sauber (German for ''Valve Cleaner'').

The Ventil Sauber is some caustic stuff. One bottle will effectively give your engine a ''carbon enema''. You can get some here:
http://gprparts.com/brands/lubroMoly/iframe.asp?http://gprparts.com/item.wws?cookieID=&sku=2001&mfr=GPR:LM