Well, it could be bad or nothing. Try changing the spark plugs and make sure that you gap them properly. If that doesn't do it then its bad, it might be that your timing is off, or just a leaky valve.

 

Pressure pops... backfires are shotgun loud. All KA's do that on decel. Your stock tune is fine

 

ding ding ding.

addict hit the nail on the head..... my ka used to do it when it was n/a w/ just 3" exhaust as well, its just pressure, not an actual backfire.

 

Mine also does it after switching to the 3" cat back, sometimes it also does it between shifts if I shift slowly at a lower RPM. I contribute it to my CES light being on and my car running pretty rich. However its usually just a normal thing with switching to an aftermarket exhaust.

 

some one told me that this is caused due to the BOV not being re circulated?

 

Haha I'm pretty sure 240-kid rolls with only KA24DE power... no BOV included

 

^^hes right, unless scoots rocking a BOV on a CAI for his N/A KA.

 

Dont be jealous lmao

 

Damn scoot Ida figured you would know that one being that you know more about cars than I do. Its just part of the KA personality, actually it is just a little unburnt fuel burning up in the exhaust. My E does it too, expecially when I am slowing down in 3rd gear. Actually shot flames outta it the other night after I cleaned the throttle valve and maf.

 

I knew it was of that sort just wanted verification, but see it it cause of the 3" pipping or cause of the test pipe? Both?

 

The test pipe. I don't have a cat on my E, but I do have the stock exhuast diameter, and it pops just as much if not more than most other 4 cylinders I have heard. Finally it was me telling you something, instead of the usual you going " didn't you read that?". lmao

 

Agreed^^^

I think the test pipe would cause these pops and the full 3" inch doesn't make it any quieter. Its probably "out of the ordinary" loud because the large diameter piping adds to the sound.

 

So an ecu tune wouldn't solve this right?

 

Prolly not. But I am not really the person to ask on that one. My exhaust is prolly louder than most 3" I have heard because my canister has been hollowed out. Talk about reverberations, right at 65, which is what I usually drive at.

We should record clips of our exhausts see what they sound like with two different exhausts.

 

since when teh hell do u have headers, liar!!!.

u got stock shit son

 

Does the pop sound like its running rich? Can you smell more fuel in your exhaust than before the modifications? I could see why a more breathable exhaust/intake system would make it run lean, but richer without fuel modifications? Unless the absence of the cat counteracts?

 

Does the pop sound like its running rich? Can you smell more fuel in your exhaust than before the modifications? I could see why no cat and an more breathable system would make it run rich, but is it really worth the tune?

lolol, the ECU will compensate for the exhaust speeds, you will not run more rich or lean from changes in exhaust diameter unless you are pushing the flow capabilities of said exhaust (i.e. running 40+ psi may start to challenege it). The pop, as discussed earlier is simply due to the change in flow of air as the car is decelerating which causes pockets of turbulance in the large 3" exhaust, i can almost guarentee w/o the test pipe he'd still be hearing these pops.

 

Dude i've had a full header some time, the down pipe was like 25 off egay

 

Yeah I didn't think two such simple things could have such an effect on how the ecu controls the motor. I still agree that the 3" exhaust amplifies the sound to a small extent. Haha I was just shooting ideas out there.

 

they do it with or without a cat...

 

yup, but putting the cat back on will make it less noticeable

 

Na, this is from exhaust leaks. You all are wack.

 

I have a stock cat and mines very noticeable. I am also running rich which may play some role in it.

 

also the stock timing on the 240sx is 20 degrease advance. in most it is only cars the advance is 10-15 degrease. this will also add to it. yes it can be caused from leaks in exhaust, but that also is a pressure problem.

 

^Stock? I thought you had an eGay exhaust?

 

because your running on a MAF. the more air that is sucked in by the motor the more fuel the ECU calculates to spray in compensation.

Very true... My quick to reply honda trained brain forgot about the MAFS. I guess it would correct the air/fuel ratio as long as the injectors don't max out, which won't happen with such a low tuned setup.

 

timing is off to much

 

lol fail

 

^:12dunno, it's stock timing