Let me start with saying that my Z runs PERFECTLY. Smooth idle, no tapping/pinging/banging from the engine, no overboost/boost creep... The A/F ratios are spot on where they should be. The coolant is not contaminated with anything. I mix 100 octane in the tank every now and then to give myself a little margin of error on my 93 octane tune. I regularly change the oil with Mobile 1 10w40.

Anyway, I just got back from the northeast "Monster Cruise" down to NC and someone commented that whenever I really got on the gas, I leave a cloud of thick black smoke behind me. I don't know if this is a new thing since I normally am looking straight ahead when I boost and usually, I only do so at night when the roads are empty.

Any thoughts on what this may be?

BTW, here are my mods:
https://my350z.com/forum/forced-induction/186561-aps-tt-w-cats-dyno-attached.html

Thanks in advance for your thoughts.

 

black smoke= burning gas. You must be getting incredibly rich on WOT

 

you're running rich....get a better AFR reading and retune

 

I'm running AFR's in low 11's at WOT in the higher rev ranges. I will see it drop to 10.9 every now and then for a moment, but mostly I hover around 11.2-3. That's rich, but not THAT rich.

 

Welcome to the fun filled world of turbos!

 

just running rich, my z smokes like that too but I opted for a safe tune AF wise. I leave em in the dust w/ some wonderful air to breathe LOL. My bumper is turning black from the soot around the tips.

 

Is this happening during WOT or on decel from WOT?

 

recalibrate your wideband. it could be reading inaccurately.

 

I dont think you can re-calibrate the PLX WB....I could be wrong though.

 

Just WOT. Not on decel. By the time I hit the brakes and look back, the cloud is far behind me.

Sounds like people agree that it is just from a rich condition. I always knew that rich=black smoke, but I just didn't think it would make that much smoke... especially with AFR's in the low 11's and cats.

It also seems odd (though certainly possible) that I could have been driving this car 3-4 times a week for 10+ months and not notice it.

 

could be a turbo seal issue as well...a bad turbo sela doesnt always produce the tell-tale smoking on decel...sometimes it is towards the end of a wide open throttle run, and not as noticeable on decel...

good luck, hope it is just running rich

 

Mine is tuned the same way, and so are some others that I know. From what I've been told is that its tuned this way to avoid pinging in the Upper revs. So its somewhat normal for a safe tune from what I've been told.

 

Mine does it also, noticed this last week, when I push it to 4500rpm it is fine but as soon as I gas it hard and go above 5k it leave a cloud of smoke behind me. My rear bumper is also a little black. Actually is a little embarassing to leave a cloud behind me when I do it during the day.