z4csl428

I installed a cold air intake and whenever i reach about 7600 it starts to sputter and fights to hit redline, ive adjusted the screw on top of the throttle body and it helps a little but is there something else i need to do, or is there something else wrong?...

Syonyk

Um... at least on the S4s, the screw on top of the throttle body adjusts the idle and should have nothing to do with top end.

It looks like you have a quite free flowing system. There's a possibility that the injectors can't dump enough fuel in at high RPM/load to keep the engine fed. Have they ever been cleaned?

Also, sputtering at high RPM is often related to spark plugs being dirty/old, or plug wires being ancient.

Does it always have problems, or does it rev freely in neutral?

-=Russ=-

calio64

maybe it leaning out at top end cause of the cold air

z4csl428

i havent tried to bring it up to redline in neutral to see if it does the same thing, the wires are new (less than 500 miles) as are the plugs.

the screw i was adjusting wasnt the idle, whenever i screw it to the left the air filter gets louder (meaning its sucking more air) but if i tighten it down the filter gets real quiet. I had it running right when i had an aluminum pipe from the AFM to another aluminum pipe then down to the filter but the first pipe didnt fit good so i put the stock pipe from the throttle body back on and i cant get rid of this problem...

harley71105

Dude....maybe she's doing all she can....she don't know where the red line is....her redline is at "all I can do"....lol...sounds like a nice rig....congratulations

Kenteth

umm... no. That screw adjusts nothing other than an extra path for air to flow through during idle. During load that path is so restrictive that hardly any air will flow through it. why? Fluid dynamics, if the air flows through that path, it causes massive (compared to not) air turbulance. The air flows the least restrictive path (through open TB plates) and not through the path that the screw adjusts. Mind you, that path is less then the width of a pencil, its not like its flowing enough air to cause high-rpm problems.

However, the reason it gets "louder" at idle when you open it, is because more air is being sucked throught he passage, more air *IS* being sucked at IDLE. This means a leaned out idle. Great for idle. Get the idea that this screw affects power at anything above 3800 (or for that matter anything on-load) out of your head. Fill that thought by reading the FSM and removing the TB to see how TINY that path is. There is no possibility that a path less the width of a pencil will have a marginable affect on 1300ccs of displacement at 7800rpm.

WAYNE88N/A

I vote that your ignition system is breaking up at high rpm's. Cleaned up your grounds lately?

powrdby13B

dude of course it sounds like its sucking in more air when you turn it... thats why its called the "idle adjustment screw" it adjusts the a/f ratio at idle...
Sounds like bad ignition, or maybe dirty injectors.
Have you done any mods to the tb or fuel system?

Agent_D

iTrader: (2)

he isnt going to lean out n/a injectors with just a street port. maybe they are dirty, or maybe your having ignition breakup as was said earlier.

z4csl428

ill take your word for it, im not gonna waste my time taking the TB off and studying it when i need to fix this problem.

it didnt do it when i had the aluminum pipe on that went into the TB but that pipe tilted the AFM and it didnt fit like it should so i removed it and put the stock pipe back on. and if ive confused anyone: by sputtering i mean backfiring and not pulling hard after 7600....

z4csl428

i went to pick up my friend saturday (which is about 15 mins away) and when i got over there it starting raining. on my way home it was pouring, i felt my car sputter at low RPM's so i was thinking my cold air intake was sucking water, well i got home and pulled everything from my filter to the throttle body off, everything was soaked. i dried everything out, hooked it back up, and made sure everything was working fine. now the problem where it was sputtering near redline seemed to clear up a little bit, it still sputters some, but not as bad. could this make it seem like its something else?

andrew lohaus

dirty feul filter or intake element perhaps???

BlaCkPlaGUE

Maybe a bad fuel pump? or fuel regulator valve or whatever the hell it is. The engine needs more fuel to hit redline, and if it can't get it then its bad pump or injectors, thats my guess.