It was about 2 a.m. and we have this long stretch of 2-lane black-top that runs pretty much straight for about 20 miles. I was running with an Audi A-4 close behind. I had the speed up to 125, but eased up to 115 to let the A-4 catch up. After about 4 miles, I noticed another vehicle headed toward us on a side street up ahead. So, not knowing who he was or which direction he was headed when he got to the intersection, I let off of the gas. I didn't want to tap on those Brembo's at that speed. It was no biggie though and soon the A-4 and I went our separate ways home.
Two days later I met up with the driver of the A-4. He told me he wished he had a camera to show me what happened when I took my foot off the gas. He said first there were sparks followed by flames coming from my exhaust for a couple of seconds.
Now, I had the stereo blaring, so I didn't notice any pops or bangs. I usually notice a pop while shifting when the motor is warmed up. I don't have the turbo upgrade either.
I was too busy looking down the road for the occasional rabbit or coyote to pop up, so I didn't look at the Tach or Boost gauges.
You know one thing that I noticed, this baby gets up with not much action on the gas pedal. I mean there was still a long way to go before hitting the floor. Do we have one of those Toyota type electronic gas pedals? I don't recall seeing any mechanical linkage involved.

 

I wouldn't doubt that GM has the throttle curve set to give you a fair amount of pedal before the power really kicks in. It is electronic so it's easy to do. When I got the upgrade installed I noticed a change in how the pedal brought in the power. They seems to have lowered it a bit so it seems more peppy at part throttle.

I've had a buddy say there is a bit of excitement coming from the tail pipe on high throttle shifts and snapping the throttle closed (black, flames, sparks). This was a night for the flames and spark. It looks like GM runs these things pig-rich at WOT to protect the engine. I am always cleaning the tailpipe.

 

I have an automatic, and i've noticed that when I mash the throttle, there's a lot of black smoke. So I think they effectively run the LNF rich.

 

Yep, GM runs the 2.0 turbo motor a little fat. The direct injection has alot to do with that, and the really high fuel pressure. Not real sure, but I think there is no return fuel line to bleed off excess fuel when you get out of the throttle, so it goes out the tailpipe, and a lot of it gets burned on the way out. I know mine[with the wickflo muffler] pops and burbbles on deaccelatrion[mis spelled]. Sure sounds nasy tho.
Had a buddy folowing me awhile back after dark, said he thought he saw some flames out the tailpipe. Makes sense. "Moon"

 

actually they run it pretty lean, the soot is because its direct injected, think diesel. for a turbo vehicle they run real lean especially in the mid range. iirc about 14:1 whereas I personally run 13:1(running around 20psi to 6k) with quite a bit more timing. even with the turbo upgrade they run the same air to fuel. they can run a bit leaner than a normal fuel injected car because of the direct injection. when your decelerating the car should actually cut all fuel. its called dfco, deceleration fuel cut off. most forced induction cars get tuned for about 11.8-12.5 at the leanest.

 

He is correct it is just direct injection and not a rich condition. Yet the fuel is cut off when the throttle is closed.

The pop and smoke lifting off at high speed or throttle is a by product of the waste gate opening. THe release of pressure will do this. I was not aware the SS would also do any flame like the old turbo cars but it must have done this.

There is a lot of good info out there on the LNF from GM. Might Google it and learn how these new engine do what they do. They are very advanced.

The LNF is one of the best engines GM has ever done and will do well in the new cars hooked to a 6 Speed in more upscale cars like the Regal GS next year.

 

Cool! learn sumthing new every day, sort of.

 

when i had the car dyno'd after the upgrade, the guy also said it was running lean.

 

That's interesting to read that you were shooting flames pappa smurf. I don't see any exhaust or DP upgrades in your sig so I asume you have the stock exhaust still correct? Either way it's cool to know we can do that.

Later
Allex

 

speaking of flame out.. remember this video?
http://www.youtube.com/watch?v=7JVLy2fsq0M