Hoping maybe I could get some insight into the LNF and some of the things I have noticed since I have owned it.

My car is tuned by trifecta with their standard tune and has a Magnaflow cat-back and sometimes at WOT I notice that I can see a small bit of smoke. Now the only time I have noticed it is after idleing at a light for a bit, and then getting on it. And I only ever see it at night when I have a pair of headlights illuminating the smoke.

What AFRs would be considered rich for the LNF? I notice the direct injection tends to run leaner than FI setups. Is the car runnign rich from the tune? Soooo.....enlighten me?

For reference, the AFRs run around 13-13.5 at WOT. Seems lean to me but I'm used to pig-rich aftermarket turbo setups...

 

What color smoke?

 

Is this after shifting? Using NLS? If so I believe its normal ..could be wrong tho

 

It's dark out so I can't really tell if it's blue, white, or black. It's not particularly after NLS, though last time I noticed it it was after that.

The car had some semi-synth blend oil in it from the dealer, which I switched to M1 5w30 today. Is the motor picky with oil? That's my only thought. I would hate to know I bought it and it's got some blow-by or the turbo seals are shitting the bed.

 

So u did keep the engine with full synthetic right??

 

It is normal, on heavy load at wot there will be a brownish smoke coming from exhaust , even stock.

 

Yes, I went with the full synth this time instead of the garbage the dealer put in it.

 

Ok just making sure, haha and more info you do know once you go full synthetic you have to stay synthetic

 

I haven't seen actual smoke out of mine, but it's bone stock and every time I wash the back end, even if only after a couple of days, there's a black residue, so it's definitely spitting something out. Mine's had Mobil 1 since day 1.

 

I notice a nice puff right after nls.. Catless downpipe and a muffler delete

 

At WOT your AFR should be around 12.4-12.6

Youre runnin a little lean bud

 

stupid dealer!

 

The LNF money spot is 12.8, or .88 lambda.

 

Some of it could also be soot build up from inside the exhaust. It's a by-product of DI engines and going WOT can flush some of it out (like blowing through a straw).

 

Why would the dealer put Syn Blend in it? Says Mobil 1 right on the cap

You have paperwork proving this incase of any warranty issues in the future and they try to blame you?

 

I'm going to get all of their maintenance records this next week. So I will have it on record. As far as the AFRs (13-14) WOT It does kid of scare me sometimes that I'm lean. Is the OE wideband reliable on the RPD?

 

It really has nothing to do with DI and everything to do with A/F ratio. DI is actually more precise in fuel metering than port injection, so it runs much cleaner, hence better emissions and fuel economy.

Forced induction engines are naturally tuned to run richer from the factory, and aftermarket tunes typically run on the rich side for safety purposes as well. So if you see any black smoke, thats what causes it, unburnt fuel. I've never noticed any smoke from mine, but I'm basically stock with a factory catted exhaust.

I've seen plenty of supercharged cars that puff black smoke on hard acceleration, especially Cobalt SS S/C's, even stock. If you've ever seen an Evo or STI with a carboned up bumper, thats another example. My Grand Prix used to to the same thing, especially when it was cold out and you opened the throttle quickly. They load up on fuel, and it ends up goingout the exhaust in the form of a puff of carbon. Perfectly normal as long as its not excessive.

 

DI engines generate more particulate matter (i.e. soot) than port injection. Other emissions are generally better, but not particulates. You can run it as lean as you want and you'll still get soot. Hell, look how lean the stock tune is on the turbo cars.

 

You are right about the particulate matter, due to the fact that the fuel is not always atomized as well with the incoming air since it is injected directly into the cylinder and not injected into the path of the incoming air above the intake valve. Good catch.