okay, so my friends s5 n/a shoots flames at idle every 4 seconds and blows thunderous flames at redline shifts. what is the cause. its pretty crazy

 

extremely rich conditions during shifts and misfiring at idle.

neither are really desirable but on high HP setups shooting flames at shifts when really pushing the car is natural but shooting flames at idle is a big finger at a lack of care of the car.

 

Why is it natural on just high horsepower cars?
Is it not normal that my NA FC shoots flames sometimes when I shift above 7K RPM just because it is pig rich from the factory and not having a cat allows the excess fuel to go through my exhaust?

 

yea that part is true I have NA single exhaust no cats and I shoot flames.

BUt shooting flames at idle is a combination of extremely rich and some car care problems.

try posting in the 2nd gen tech section to get more info

 

I shoot huge flames when I shift at 65 or 7 when I'm running it hard....everytime and even when I let off the gas

 

n/a's are rich from the factory so that is fairly normal also but with no cats you actually are losing power so i don't necessarily consider them running right unless tuned. they run as designed, which helped to keep the cat in one piece but without it there is no need for them to run rich any longer.

 

My old S5 used to pop blue flames at idle, but it was because I had a blown apex seal and I was trying to limp it off the track lol. When everything was running all good it would only pop tiny flames on high RPM shifting or getting off the throttle at high RPMs going into corners. At the time I was only running single Apex N1 with no cats.

Basically high HP car run on massive amounts of fuel. ie. The more air and fuel you can cram into a chamber with the correct Air:Fuel ratio, the bigger the bang will be. I guess you could call shooting flames at high RPM's "normal" IF you're running straight pipe exhaust. When I was running N/A it would shoot out small flames every now and then. After I did my TII swap I could shoot massive flames all day. I never really got around to tuning though. Kept the SAFC tuned rich until I could get a chance to tune it properly, but ended up selling the project before I could finish. We lost our track here in Hawaii and slowly I started to lose interest. Anyway, I would think that tuning a car at higher RPM's to be a LITTLE on the rich side would be a safety precaution. The unburnt fuel will flow out of the motor and through the exhaust. The more open the exahust, the more farther the unburnt fuel can travel before evaporating or being burnt up in the piping.

 

Shooting flames at idle is not a good it's running to rich and is not good on the motor but shooting flames on full throttle is cool it doesn't take a high horse power car to do that.

 

My old S5 used to pop blue flames at idle, but it was because I had a blown apex seal

see this is logic a blown apex seal will make the car spit out flames @ idle what does not make any sense TEDDY is saying that on full throttle shooting flames is cool. if you are shooting flames a full throttle it means that your tunning is out of wack. too much fuel not enough air and too little spark those are a couple of things that come to my mind ... come on all you have to do to shoot flames is lay off the throttle a bit and then hammer it back down everybody knows that .
so what i would have your buddy do is take a compression test to make sure ur apex seals are ok, because no matter how rich that motor is @ iddle it should not flame out every four seconds..............

 

i mentioned a properly tuned car, only when making decent numbers should well tuned cars still pop flames all the way past the tips, on lower HP cars it is only because they are running stupid rich or the timing is way off.

 

[QUOTE=Karack]i mentioned a properly tuned car, only when making decent numbers should well tuned cars still pop flames all the way past the tips, on lower HP cars it is only because they are running stupid rich or the timing is way off.[/QUOTE

TEDDY you still have time to learn something lol

 

stuck/leaking primary injector would be my first suspect.

 

that would still not be enough , ive had cars with raw fuel coming out of the exhaust while its @ idle because the floats were stuck and still no flames, shoot it happened to teddy's dad rx7 when i first built it about six years ago, back then in the day's when teddy use to loom in my garage all the time now he thinks he is big time and i hear he thinks he can smoke me ..... like it say's below my aveter little buddy "come get some" youve got my # and know where i work and while your at it y dont you bring me the money you owe me for porting those rotor housings 4 ya
anyway goin back to the flaming exhaust last year during the nhra sport compact season opener in west palm beach fl we had an injector mess up on jesus padillas all motor rx7 and still no flames from the muffler @ idle call me crazy but i belive its something else

 

If a FPR takes a crap it can dump fuel into the vac system. Pull off the vac line going to it and see if it is leakiing fuel on the vac side.

 

thanks

 

Hey Karack, is it not common to run a (fairly) rich fuel map on most turbo applications?

I don't blame anyone that shoots flame on shifts and has a turbo... I call that fire "engine insurance" heh. Am I wrong here or what?

--Gary

 

it is safer but you will lose some gas mileage.

 

This is a rotary forum, we don't know the meaning of "MPG" ;P

--Gary

 

all we know is car mileage =P