Backfire

[tibbar650]

I have a 1995 240sx, it backfires when you let go of the gas, usually at lower rpm's (2-3k) sometimes, but less frequently at higher rpms. I also noticed there is much more significant amount of backfire if OD is on. (its a auto)
I have a GP sports exhaust with 3 inch piping, running on a stock intake. I would like to know if the car is running rich? Or is it just because of the 3 inch piping due to the lack of back pressure. Should i worry about it?

[cencal180]

yea, its fine. my cousin had a gp exhaust on his fastback always poped at 2-3K rpms..my friend has a 95 S14 with an N1 pops at the same rpms. so you should be normal from what i can see. correct me if im wrong.

[surge s14]

mine pops too no worrys man

[tibbar650]

aight thanks, yeah i was a little worried, i had it pop really loud once, so i thought something could be going bad. :0 I bought the exhaust for 50 dollars. ;)

[NemeGuero]

you're running rich..

exhaust leak possibly..

[clutch kick drifter]

if you have a SR, get used to it. Mine back fires in btw every gear and then likeevery time in btw that :wiggle: , if a Ka, just running rich, check timing.

[smelly240]

at least ur not shooting 4 foot flames - every now and then i get a good one (one night i blew a oil seal b4 i installed a restrictor - and i shot one that lit up the neighborhood - like WHOA)... most SR guys shoot lots of fire. on a stock car tho - popping is semi normal when u add exhaust. less backpressure so it - naturally - goes outta tune a lil bit.

my one buddy has a ka-t and that thing pops constantly. I dont run a blowoff valve so i dont have the every gear popping stuff.

[SoSideways]

I get pops between every shift, but no flames.

I used to get flames on the decel (the infamous 1700rpm pop/flame) but I have not gotten anything since I fixed my BOV issues.

How are you guys popping flames still?

[smelly240]

my car does it when it wants i guess... like if i lift and get back on it - maybe its my tip-in? maybe bc i have big injectors? i just know it does it when i drive it hard.

[Replicant_S14]

exhaust leak possibly..

Probably. It's hard to get the flanges on 3" stuff to mate with o.e. sized stuff. On top of that, 2 bolt flanges suck anyway.

[RalliartRsX]

Probably just running rich from exhaust. From my understanding, with a stock ecu optimised to run with the stock everything, adding a larger diameter, free flowing exhaust will actually have the computer running slightly rich to compensate for the increased flow. Simple fix is to get a fuel pressure regulator.

I have the same problem (signs are incessant backfires and pops regardless of rpms, entire rear end is covered in sooth, crappy MPG, etc.)

I actually find it quiet ammusing as when I drove my car to school every once in while, whilie chugging around campus, it would just do a loud 'pop' and people would drop phones and walk into poles!!! So freaking funny (until I realized I just left about 10 gallons of gas on the back of my car from running rich and and empty wallet :duh: )

[nsn240]

at least ur not shooting 4 foot flames - every now and then i get a good one (one night i blew a oil seal b4 i installed a restrictor - and i shot one that lit up the neighborhood - like WHOA)... most SR guys shoot lots of fire. on a stock car tho - popping is semi normal when u add exhaust. less backpressure so it - naturally - goes outta tune a lil bit.


4 foot flames for ~6 seconds :)
(only cause my timing was off though)

backfiring, popping... whatever.. doesnt hurt anything, sounds cool haha

[SoSideways]

Well all of my pops happen in between shifts, when the BOV doesn't even open cause I want it that way, so I'd hear compressor surge and a pop.

I think as a matter of fact my car runs lean until I boost and the BOV opens for the first time, then after that it'll run rich.

TPS voltage = 0.37v closed / 4.07 WOT

Timing at 15 degrees BTD per stabbing the CAS according to the FSM.