VTsuckah

iTrader: (1)

https://www.clublexus.com/forums/is-...eanliness.html

The 'soot' is common. I remember another thread concerning this issue as well.

hirsch2is

i just noticed VTsuckahs post about the diffuser too. very likely culprit as well

darylrsv4

iTrader: (2)

I have the same issue with my M2 exhaust. Pretty sure it's the carbon issue. No idea why it wasn't happening with your stock exhaust. Maybe your carbon issue has gotten worse?

FSportIS

iTrader: (13)

Oh interesting. How many days after driving do you see the layer of dust on the rear bumper and trunk? You have IS250?? It seems like smoky, and me with IS350 don't have this issue. Only the IS250 has.

Well, I did not have this issue when i bought the car brand new. Few weeks after switching to FSport exhaust, I started seeing exhaust black dust all over my back of the car after about few days of driving.

To all, if you have a IS250, do you have this problem?

darylrsv4

iTrader: (2)

Only normal road dust on the bumper. Couple days on the exhaust tips and I notice a black build up.

smokyis350

iTrader: (21)

I can't tell right now. I haven't washed my car in a few months

VTsuckah

iTrader: (1)

Another plausible reason for having dark soot on your rear end is from brake pad dust and the wind vortex created from the car's aerodynamics. It's very prevalent on white cars.

PLEASE take a picture of the areas of concern so that we can provide you with better insight. If there is dust all over the rear end vice just around the exhaust tips, it is highly unlikely that it's from your exhaust.

FSportIS

iTrader: (13)

Below is the picture. This fine layer of dust are only present in the rear bumper and the trunk, not anywhere else.

I think your speculation on the brake dust is a good one but not likely to be in my case. My wheels/tires are even cleaner than this. Also I use Akebono brake pads which has very little dust. My IS350 also runs on the same pads and do not have this dusting issue.

minato

iTrader: (1)

I have an 08 250AWD and do not have this problem,or havent noticed it. I have the no emblem fsport exhaust.
I drove from montreal to ottawa this weekend, and the usual, passenger side exhaust was black inside
I will keep an eye on it though. since the exhaust is black inside some of the soot should probably be getting outside in the air / on the car

IS-SV

Unfortunately quite common with DI gasoline engines. Those of us w/darker colored cars notice it mainly on tips.

Future DI gas cars in Europe might require cheap DPFs to hit emission standards.