Yup, like it says. I just rebuilt my motor with CP 9:1 OS pistons, eagle h beam rods and new bearings on bottom end. Anyway, i used to have JDM ITR pistons in there and had no problems as far as crap on bumper goes, but now its all over the place. Right above the muffler its pretty thick, then it just extends all over the back of the car. When i drive there is no smoke and it smells pretty normal, even tho i have had some kids say my car smells like it runs rich even before the build up. Now here coems the question, i know its most likely running real rich, but what would cause that after just a build without touching fuel or anything? also how can i fix it? and one last thing, i have a VAFC sitting here at home waiting to go in with the turbo in about 2 months, can i install that and lower fuel at all and help this situation if it is running rich? i know this is a long thread but i figured id cover as much info so there wouldnt be too many questions. So fire away people, thanx in advance.
BTW, its a 94 GSR

 

Every honda i've ever worked on blows some soot out the back. If its running REAL rich, it'll do that more than others. Honda tuned the stock ecus to run rich to prevent problems with crappy gas, real hot days, etc.

If you get the engine properly tuned it'll fix that :up:

 

are you throwin any codes? if so your o2sensor might need to be replaced or cleaned...but yes a vafc would help you greatly. get a vafc and a air fuel ratio gauge and you should see some improvement.

 

i had problems with the O2 sensor a while back, i replaced and am currently not thowing any codes...in fact i am in the middle of installing the VAFC right now and i have a Autometer A/F running right now too...any other thoughts? or why it would change so much with just change in pistons?

 

anyone else? i just hooked up VAFC and adjusted the fuel down -4% below vtec at narrow and wide throttle. is this wat i wanna do?

 

ok i just drove around for a while and messed with the vtec controller, all i really did was lower the fuel settings below vtec starting at idle...the idle setting at narrow throttle are at -7 right now and go up from there slowly to vtec, so i hope that helps with the running rich problem, any other thoughts on y this would start after new pistons?

 

Rings not seated correctly?

 

i thought about that too, but really the car running rich and the carbon cant really have anything to do with the carbon build up...cause then i would be burning oil. Im going to take the car to the machine shop tthat did it tomorrow and have them listen to the light tap and tell them the story and see what they say, but im still lost as to how its running so rich