Mazda3 Forums banner
1 - 20 of 22 Posts

·
Registered
Joined
·
77 Posts
Discussion Starter · #1 ·
Do all of you guys have black residue (from smoke) around your exhaust tips? It is enough o cover the top half of the tip and more? Also, when you accelerate hard in the freeway around 60mph, will a puff of black smoke come out of the exhaust tip? ARE THESE SIGNS NORMAL?
 

·
Registered
Joined
·
6,157 Posts
Yup, this car runs pig rich. Welcome to the club, drive and enjoy :agbullet:
 

·
Registered
Joined
·
6,157 Posts
Yay EMS !
 

·
Registered
Joined
·
77 Posts
Discussion Starter · #6 ·
[quote author=Mattleegee link=topic=80784.msg1495178#msg1495178 date=1182134053]
yeah a big puff of smoke...

i do it to people on purp0se :chuckles:
[/quote]

Great, because my buddy from behind told me he saw a puff of black smoke in the freeway. So i thought maybe something was in my engine to cause that.
 

·
Registered
Joined
·
1,960 Posts
[quote author=DreamMazdaRacer link=topic=80784.msg1495162#msg1495162 date=1182133763]
Do all of you guys have black residue (from smoke) around your exhaust tips? It is enough o cover the top half of the tip and more? Also, when you accelerate hard in the freeway around 60mph, will a puff of black smoke come out of the exhaust tip? ARE THESE SIGNS NORMAL?
[/quote]
Yes, these are normal signs for many cars.
 

·
Registered
Joined
·
2,935 Posts
[quote author=DreamMazdaRacer link=topic=80784.msg1495162#msg1495162 date=1182133763]
Do all of you guys have black residue (from smoke) around your exhaust tips? It is enough o cover the top half of the tip and more? Also, when you accelerate hard in the freeway around 60mph, will a puff of black smoke come out of the exhaust tip? ARE THESE SIGNS NORMAL?
[/quote]

welcome to super rich turbo engines.
 

·
Registered
Joined
·
36 Posts
I don't really think that our cars in general run richer than any other newer cars given the strict emission standards they are forced to meet (Tier II, Bin 5 on my non-California MS3, I am not sure if the CA cars have to meet a stricter standard or not). Under most driving conditions, gasoline vehicles operate right around a lambda value of 1 after the catalyst reaches operating temperature. In fact, the three-way catalysts installed on gasoline vehicles require the fueling strategies to pertubate between rich and lean modes very close to stoich so that they can effectively catalyze the exhaust.

The real "problem" with our cars is the direct-injection. DI cars like ours are predisposed under certain operating conditions (typically cold starts and WOT accelerations, where the engine is in open-loop) to form particulate matter, just like a diesel engine does. It is this PM that I believe is creating the black smoke, fouling our tailpipes and turning our oil prematurely dark.

I talked to some of our diesel testing guys at work and apparently the DI creates localized rich zones in-cylinder and these zones are where the carbon atoms join and form soot. There have been a lot of studies on this subject by the EPA, CARB, OEMs, the EU agencies, every catalyst and particulate filter manufacturer, etc. for both diesel and DI gas engines.

If I ever get a wild hair (and the opportunity) I am going to instrument my car with both wide-range O2 and standard switching sensors and run it on the dynos at work through the standard emissions certification test that EPA uses just to see exactly where our cars are running under normal operating conditions.
 

·
Registered
Joined
·
53 Posts
[quote author=CTGrey02 link=topic=80784.msg1534713#msg1534713 date=1183471573]
I have yet to see this from mine. There is soot on the exhaust tip when I wash it but it's not that bad.
[/quote]

Mine too...I've had the car for a week...I'm glad to learn that it's normal for these cars...
 

·
Registered
Joined
·
1,960 Posts
[quote author=Detroit link=topic=80784.msg1531705#msg1531705 date=1183344004]
I don't really think that our cars in general run richer than any other newer cars given the strict emission standards they are forced to meet (Tier II, Bin 5 on my non-California MS3, I am not sure if the CA cars have to meet a stricter standard or not). Under most driving conditions, gasoline vehicles operate right around a lambda value of 1 after the catalyst reaches operating temperature. In fact, the three-way catalysts installed on gasoline vehicles require the fueling strategies to pertubate between rich and lean modes very close to stoich so that they can effectively catalyze the exhaust.

The real "problem" with our cars is the direct-injection. DI cars like ours are predisposed under certain operating conditions (typically cold starts and WOT accelerations, where the engine is in open-loop) to form particulate matter, just like a diesel engine does. It is this PM that I believe is creating the black smoke, fouling our tailpipes and turning our oil prematurely dark.

I talked to some of our diesel testing guys at work and apparently the DI creates localized rich zones in-cylinder and these zones are where the carbon atoms join and form soot. There have been a lot of studies on this subject by the EPA, CARB, OEMs, the EU agencies, every catalyst and particulate filter manufacturer, etc. for both diesel and DI gas engines.

If I ever get a wild hair (and the opportunity) I am going to instrument my car with both wide-range O2 and standard switching sensors and run it on the dynos at work through the standard emissions certification test that EPA uses just to see exactly where our cars are running under normal operating conditions.

[/quote]

Because of the catalytic converters, of course the A/F ratio is stoich under idle and cruise conditions.
At WOT and under high load, the A/F ratio is in the neighborhood of 10:1.

You can read the equivalence ratio directly from the diagnostic (OBD-2) port via the ECU in realtime (one of the O2 sensors is wideband).
 
  • Like
Reactions: hatch06
1 - 20 of 22 Posts
Top