I need some advice on how to cure a running rich problem I have with my 94 prelude VTEC. Whenever I get on the gas more than half way or so a pretty large amount of black smoke comes out of the exhaust. My prelude has 133k on it now. I recently changed the plugs. Any other suggestions on what to do?
Thanks.

 

Check the cap and rotor, that's the only other weak link in igniting the whole mixture. Beyond that, make sure your air filter is clean. Preludes are pretty notorious for running rich anyways, but black smoke is a bit out of the ordinary.

 

correct me if i'm wrong, but isn't black smoke usually oil? rich is usually a bluish color isn't it?

 

You have it backwards.

 

I thought oil was black and fuel was bluish. Because, my car right now is running with tons of smoke coming out of the back and it is a bluish smoke. I can back that idea because I know my car is running rich. I have a swapped gsr into a civic. I have to get an aftermarket adjustable fuel pressure regulator so that I can lower my fuel ratio that way I run better and take the risk away of detonating the head. Also, how exactly do you detonate the head? I ran rich tonight racing 4 times and nothing happened. I would suggest to you that you somehow check the fuel pressure and make sure its not off. Also, take your intake off and while reving your motor at around 3 grand, spray carb cleaner into your throttle body. This should help clean carb build up if you have any. That can cause smoke sometimes. I know I have carb build up like a mother because I put new denso spark plugs in, idled the car for 3 minutes and took them back out and they were covered in black crap. I mean the way a very old spark plug looks. Its crazy!

 

blueish-white smoke = oil leak pass the valve seals
black = running rich

~~mazin

 

For the record:
Oil burning = bluish smoke
Running rich = black smoke
Please explain how lowering your fuel pressure will lower your chances of detonation? Since less fuel means the a/f ratio is more lean, that means you are CLOSER to detonating than running rich.

 

no, where I stand is running rich. If you decrese the richness, you become stoic equaling a lesser chance of detonation.

 

actualy... running rich will NOT cause detination... detination occurs when there is NOT enough fuel.. not TOO much

 

Exactly.....a stoich mixture is closer to lean than rich, and lean is detonation...rich is too much fuel :roll: