Black soot from exhaust?

[RS12Turbo]

Recently when I crank up the car, and let it idle for a few minutes, it will spit black soot out of the muffler onto the garage floor. Does this mean it's running rich? I've had the engine for almost a year, and this didn't start until a couple of weeks ago. Also the exhaust smells kinda rich or something now too. I pulled the plugs, which are IX 7's, and are almost a year old. All 4 were very clean.......a little black right above the threaded edge, but the electrodes and everything else were clean. I've heard the stock fpr can't handle a walbro 255, so I'm wondering if mine is starting to let go.My old ca18et did this for years, and I assumed it was always running rich, but not for sure.....the plugs on it were always BLACK, even after a couple hundred miles

[r34 gtr]

Sounds rich to me. My car used to do this when it was running really rich, and so did my mom's Volvo 850 turbo. Get a gauge and check your fuel pressure. How much soot is it spitting out? Mine would turn your hand black if you put it in front of the muffler when the car was cold.

[RS12Turbo]

Sounds rich to me. My car used to do this when it was running really rich, and so did my mom's Volvo 850 turbo. Get a gauge and check your fuel pressure. How much soot is it spitting out?

Maybe a 3 foot long trail, x maybe 1 foot wide. I'll hold up my hand in front of it, and see what happens.I'll get a gauge and see what it the pressure is. Also....if I let it idle for 10 minutes or so, I'll get smoke from the exhaust. Only at idle....under boost it's clean. I had the smoke problem before I got it dynoed tuned a few months back. Once they leaned the crap out of it and got the afrs back to normal on the afc2.....the smoke problem went away.....now it's back along with the soot splatter

[buddy_s13]

i have the same problem, accept mines been doing it for ages. i was told it was running rich, but yeah it spits black unburnt fuel when it idles. i **** white sock in front of it and gave it a rev n dam was the sock black. also it gos all over the back of my car.

i have a walbro 255 and stock injectors so if anyone could confirm the theory about the injectors and the fuel pump not liking each other that would be great.

[buddy_s13]

sorry didnt mean injectorsfpr + 255 = spiting?

fpr = fuel pressur regulator?

[rico05]

Mine does the same, but I know I am running rich and I have no catalytic converter. Honestly, it is not a big deal. More fuel = less detonation. Get a wideband and check your AFRs and trim them accordingly with your SAFC or base ROM as needed.

buddy_s13: You are correct. A high flow/high pressure pump can overwhelm the stock, old and junk FPR. I run a Nismo unit, as it is the easiest to instal, but I have heard of them developing vacuum leaks. When I completly build my motor here eventually, I will run an Aeromotive FPR. Rock solid construction and great reputation. If you run an adjustible FPR, you will need a fuel pressure gauge so that you can properly adjust the fuel pressure to 36psi with no vacuum.