Dark "Soot-Like" deposit on tailpipe

[fxpthl]

Enthusiats all, after a great drive up to Yosemite and many twisties in between there and So. Calif., I noticed that my tailpipe was pretty much covered with a black, chalky substance! It looks to me like the engine is running way too rich and if so, how do I adjust that? If it is something that a professional should do then so be it, but I am not afraid to get my hands dirty if it saves me a few tokens in the process. BTW, I didn't see any type of smoke while driving these over 1100 miles and it was a great run for my Ebay- bought 97 Miata. All toll about 20+ cars attended this event from So.Cal.Miata Club as well as SJMC, Carson City,NV club too.

 

[fxpthl]

So....61 views but not one suggestion, answer, anecdote or anything else!? Perhaps this subject is just too mundane for this forum or my question is so dumb that there isn't a brave soul out there to tell me so. Either way, I will simply hope that someone will give me the benefit of the doubt and throw at least a comment of two on this subject. Everyone have a great day and for those of you in the path of "Sandy"...........time to leave or batten down your hatches!

 

[Tillos]

1. Is the car a speed or N/A?

2. What modifications have been done to the ECU, if any?

3. Check MAF/plugs/filters/pump/o2sensor/etc

If it's really REALLY soot-covered moreso than a normal car would be after 1,000 miles of driving, then it could be something to look into... but you also did travel quite a distance

 

[fxpthl]

Thanks for your reply and comments Tillos. This is a normal / stock NA with the 1.8 engine. No modifications at all mechanically. O2 censor is fairly new and all the filters are good. I guess just traveling all those mile just might be what I am seeing. Thanks again.

 

[THE Phen]

Unfortunately, it's a Mazda. Mazdas run pig rich, especially dealing with altitude changes.

 

[WillD]

I agree with Phen on this one, sounds perfectly normal.

You might want to check your catalytic converter too. I've read that when people don't run a cat at all or when it goes bad that this happens. But I wouldn't bet on this.

 

[fxpthl]

Thanks for the replys. My 97 M Edition has just over 182K on the chassis but only about 80K on the new/used motor. Does that kind of mileage dictate that the cat. is bad? Only asking because I just don't know the answer!!

 

[THE Phen]

If it's a factory cat, then it could be plugged up. It's really hard to say exactly when a cat will go bad since it's a wear item and no two people drive exactly the same. Example, we had a Mercedes 190E with the factory cat at 335k miles.