zlancer

iTrader: (1)

well...i just installed the RRM test pipe. that was supposed to get rid of the popping noises becase the theory was extra gas was running through my motor and exploding off the cat. WELL...there is no more cats for the gas to explode off of but there is still a POP. this is what happens:

1. Before i installed the Test Pipe and had 1 cat
in 4th gear at about 2000 rpm when i give about 8% throttle then let off real quick there was sometimes a POP. this i thought was from the extra gas hitting the cat and there was a bubbling noise at that rpm range. also...then i put the car in any gear (2nd seems to be the most) and i let the engine slow the car down...it slows down..goes slower...slower....slower then at about 1,100 rpm it feels like there is a release and then it coasts. what is that??

2. After installation of Test Pipe
in 3rd gear it now makes a POP at 2000 rpm again...and there is like a "bubbleing" noise at the rpm level...i'm guessing there is still too much gas...but what can it be exploding off of...the exhaust???? and the release is still there at like 1,100 rpm....

I still don't think it is an actual backfire because its not like i'm straining the motor. i'm only crusing in 4th or 3rd at 2000 rpm and not like going WOT. .....ne ideas????

CivicEater

the release is your engine getting close to it's idling RPM.. the closer the car gets to that 900-1100 RPM, the less it's gonna help slowing down the car..

as far as the backfiring.. it may just be something that happens normally, but you couldn't hear with a stock exhaust.. My theory is.. the less backpressure, the farther down your exhaust the gasses travel before exploding.. which makes the popping louder than you've heard before.. Do you have the stock muffler still? try putting it back on the car.. see if the popping goes away.. ??

zlancer

iTrader: (1)

ne 1 else have ideas????

DaTenshi

what about increasing the piping size to a larger size from the headers down~

zlancer

iTrader: (1)

i already have 2.5 inch

Smoktout

iTrader: (1)

mine makes the same noise, i think it's a natural noise. i hear it a lot from cars that have custom exhausts, turbo and NA.

zlancer

iTrader: (1)

its pretty loud tho....i'm not talking like a lil pop...i'm talking like a gunshot noise sometimes....i'm just making sure that i keep persisting....i don't want my engine blowing up.....are theye any experts out there???? do you moderators know about this?

bahamut

Sound like you are extremely rich on the low rpm end (not going to give advice since I haven't seen your set up) . . . do you know any local DSM'ers? They might help you on your learning curve . . . yes, at times, they maybe be arrogant "no 4g63T = no help" (steer away from those) . . . you gotta find those gearhead wanting to fix up stuff.

ishi

Do you have a knock sensor? also I noticed you have aftermarket
injectors?? right? Have you invested in an after market ignition system? More fuel ...need better and hotter spark to ensure full detonation of fuel... My EVO 4 backfires too but not at such low RPMs. Invest in the knock meter first.(cheaper) HKS make one and there is one on POWER FC COMMANDER(mine)

3K

iTrader: (9)

Deceleration backfires are usually caused by a lean condition.

You might want to check your A/F ratio to make sure your not leaner then 17.1:1 ratio during deceleration.

You could get an autometer A/F gauge to check on this. They're pretty cheap but not very accurate, but at least it would give you a better idea of what your A/F is like.

Your best bet is to run your car on a dyno, or if you know someone with a lambda meter you could get an exact A/F ratio that way.

KMcW

Its called backpressure, your exhuast is sucking air back into the engine when you let off the gas. Thus the pops. No biggy, if you don't like the sound, turn your radio up.

3K

iTrader: (9)

Actually it's called reverberation when air is sucked back into the engine.

Backpressure is created when you have a bottleneck in the exhaust flow.

stealth-wrx

its completely normal. all cars do it.

reverberation? a reverberation would be like an echu effect.

http://www.dictionary.com/search?q=reverberation

i was covinced it was called reversion. hence most companies making anti-reversion chambers create a vacuume and assist pulling air out of the cylinder. the dynamics are called the venturi affect.

read about anti-reversion here.

http://www.hytechexhaust.com/who_we_are/who_we_are.htm

3K

iTrader: (9)

That's right "reversion" sorry my bad.