Black soot on rear bumper above exhaust pipes?

xavier

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Pearl White 2007 Mazda CX7 GT with Tech Package
I know I have a color that will show this pretty easily but the fact that its showing up kind worries me. I'm having some black soot buildup on my bumper around the exhaust pipes. Anyone else experiencing the same? Im thinking its an indication of running rich? If im running rich enough to have a fair amount of buildup at 3100 miles, how do my plugs look? (ughdance)
 
Mine is black, so it wouldn't show that easily. However, the inside of the tips stays sooty, even after a 400 mile interstate highway drive. I've been told by my service advisor that it's normal.

I think that that particular hatch back tends to suck exhaust back toward the body more than the average body style does.
 
I have a RX-8 that has the same thing. May it be inherent to the Mazda family????
 
Definitely running a bit rich....Solution..I have no idea with stock ECU, and yes the RX-8 is a oil eating engine....Be sure to constantly check the oil and refill as necessary...
 
ProtoType5 said:
Definitely running a bit rich....Solution..I have no idea with stock ECU, and yes the RX-8 is a oil eating engine....Be sure to constantly check the oil and refill as necessary...
Yeah, I figured it was running a bit rich. Maybe 1 of the ECU updates that Mazda is working on will bring the fuel/air a little closer to where it should be. If not, I guess safe is better in the long run
 
Most new vehicles run on the rich side to play it safe... this is a pretty common thing with every vehicle I've ever owned.
 
It's a turbo...it'll do that. You should've seen my '97 Eagle Talon Tsi AWD. But...my 300ZX is like that and even my TSX has torched its pretty twin pipes black. Nothing a little cleaning and rubbing can't get off.
 
never dull for pipes?

offset_98 said:
It's a turbo...it'll do that. You should've seen my '97 Eagle Talon Tsi AWD. But...my 300ZX is like that and even my TSX has torched its pretty twin pipes black. Nothing a little cleaning and rubbing can't get off.

What do you (or others) suggest for cleaning? I miss my pretty chrome tail pipes. I picked up a tub of nevr-dull, but haven't tried it yet. Is that product a good choice or likely to cause harm. As you can no doubt tell, I'm new to doing this kind of thing. Thanks for any advice.
 
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UpNorth said:
What do you (or others) suggest for cleaning? I miss my pretty chrome tail pipes. I picked up a tub of nevr-dull, but haven't tried it yet. Is that product a good choice or likely to cause harm. As you can no doubt tell, I'm new to doing this kind of thing. Thanks for any advice.

for me i just use a chrome polisher, my tail pipes still are lustrous with it
 
Use some S100 soap on the pipes works wonders and will also quickly remove the soot from the panel without any marking/damage. Found this problem to be very noticable on my wifes white CX-7 although I can not see it as well on her new Copper Red, although the cleaning sponge used shows the same problem. I also have two MX-5's requiring the same cleaning. So either I have four Mazdas running rich or its just the nature of the design. I will guess it's the latter.

S100 is available at most Harley shops and you can always check out their (S100) site for more product information.

-Gary
 
Thanks you guys (and my apologies for the hijack.) I fear no more. I just used the chrome cleaner/polish and it worked like a charm. My tail pipes are gleaming again.
 
I've had 3 mazdas and my gf drives a 6... all 4 of them have the soot issue. My MSP is the worst, especially before I put the AFC in to lean out the Air/Fuel curve. I would guess that's the same issue with the CX7 as Mazda generally tunes the car rich to make sure it doesn't blow up! Once someone tunes this engine you'll be shocked by how much more HP and performance this thing is capable of.
 
how much improvement would you see if the engine was tuned properly to run a little leaner? Will this car even pass an emissions test with as much exhaust residue as it makes? I have a F-150 with many miles on it and the inside of tail pipe still looks like new without any soot or exhaust deposits. But my old bimmer with triple 40 dcoes may never run lean enough to produce a clean exhaust without a loss of power.
 

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