I have a 2000 GSR and just noticed some major black spots on the rear bumper after not washing the car in a while, looks somewhat like oil spots.

Has anyone had this problem and what does it come from? The car still runs very strong and I had a leak down test done not to long ago and it came back fine (no leakage).

Please advise. Thanks in advance.

 

maybe runnig rich ?
what other mods do you have. ?

 

AEM ITR CAI
Skunk2 Manifold
Skunk2 Cam Gears
VAFC
DC 4-1 (soon to be replaced with JDM)
Apex N-1 cat-back

 

Maybe you have that V-AFC dialed in a bit too rich in certain RPM ranges. Have you had it dyno tuned?

 

The VAFC has not been dyno tuned yet but there have been no adjustments made to the fuel on it either. Only thing that was done was we raised the VTEC x-over a little bit b/c it responded better with the manifold (nothing major, I think like 4600 on 4500 off).

Thanks for all the help so far guys. I am having my clutch/flywheel installed next week Wednesday so I will have my mechanic take a look into it also.

 

you could lean it out a bit with the vafc

 

im betting the vafc and the cam gears.
just my .02 though.

 

are you running a cat or test pipe?

 

No test tipe and it's still the stock cat. There is going to be a carsound cat going on with the JDM header but it's not on yet.

 

yeah its usually because of exhaust fumes from rich combustion. i get it all the time since i got turbo.

 

I'm pretty sure you are running rich. Happen to me on my old integra, **** load of black sport on tip of the ehxaust and bumper area.

Since you have the vafc, I suggest you lean the car out as soon as possible before it destroys your cat. converter and o2 senosr.