Exhaust Backfire (Blessing or a curse?)

[spux]

Guys, got a question hope u guys cud shed some light on,

I drive a 02 s15 silvia Spec R. Car's great and all, but my car constantly backfires under certain circumstances, especially after a hard drive or when im dragging the car in the lower gears.

It sounds like a loud Bang/Boop and it is not continuous. It is just one bang after i change gear and the loudness vary from subtle to thunderous! (might have caused a few shock induced heart attack as i tear down the LDP)

While sometimes i liked the attention the backfire creates, but i cant shake the feeling that something might not be working optimumly.

Hope u guys can share your opinion on this issue.

Thnx
Spux

 

[rajie]

maybe ur car is running rich .....im also having this problem with my car
according to a few people my fueling is very rich ....
just my 2 cents might be wrong

 

[spux]

Rajie,

Thnx man, ive consulted a few and some have given me the rich lean theory. It made perfect sense, the only thing is that i have never meddled with the fuel air intake system. Maybe the previous owner in Japan tuned it.

Anyhow, running rich is always safer than running lean anyways, especially with the malaysian weather, dont want the lean mixture to cause knocking every other rev cycle.

cheers dood
Spux

 

[jinkl]

how about blow off :P , r u using a blow off

 

[liz@rd]

2 words for you "yeng loh" ... get it tune is better IMO ... running rich but not up 2 performance but wait s15 spec R ... well still fast ... anyway mind me asking how's the FC ?

 

[SubVerSiv]

Is the car equipped with:

1. Aftermarket blow-off valve?
2. Aftermarket air filter (open pod type)?

When you rev your car at high RPM, does the exhaust emit visible black smoke?

If it does, then most probably your car is running rich.

Running rich can be considered as only a waste of fuel.

 

[spux]

Hey Guys,

Thanx for the reply. Much appreciated. In answering u guys:

1. Yes, I am using HKS bov

2. Yes, I am using Apexi Air filter

3. No, when i rev high, very rarely does black smoke comes out from the exhaust. Only when i have not rev high for a week or two then there's black smoke for a couple of second, but it does not repeat itself again.

4. The fuel consumption is manageable. In the city i get about 360 KM for RM130 full tank when the light comes on. If i drive on until empty i suppose it can do about 420 km for RM140+

Thnx guys

 

[8229]

hello guy...

im newbies, as my exprience this problem maybe from ur exhaust magnifold, since ur fuel consumption is ok... check if there have any leak between the exh. gasket, or any screw have been loose, or if there have any crack at ur exh. magnifold... its hard to check, if the leak is small, i had this problem before with my vr4, and some of my evo friend...

 

[jinkl]

Hey Guys,

Thanx for the reply. Much appreciated. In answering u guys:

1. Yes, I am using HKS bov

2. Yes, I am using Apexi Air filter

3. No, when i rev high, very rarely does black smoke comes out from the exhaust. Only when i have not rev high for a week or two then there's black smoke for a couple of second, but it does not repeat itself again.

4. The fuel consumption is manageable. In the city i get about 360 KM for RM130 full tank when the light comes on. If i drive on until empty i suppose it can do about 420 km for RM140+

Thnx guys

yeah i understand, many users and mechanics dont know bout it, u r using a Air Flow Sensor fitted cars , u r not supposed to vent out , u r not supposed to use a BOV , u supposed to blow that back into ur intake , once u blow out, the ecu has already got the reading from the MAF that you have AIR , it will still supply fuel and further make the car run rich , and u get a POP , u r lucky enuff that ur car doesnt die off, some ppl face die off , this scenario only happens when u shift gears or cruise on the highway and while u lift off ur accelerator, the bov opens up

 

[monazarudin]

Some people say that if that happens, it means that you have the perfect configuration for your car..., but I don't know how true that is... You should get your friend to follow you in another car and see if flames come out of your exhaust when this happens...

 

[jinkl]

Some people say that if that happens, it means that you have the perfect configuration for your car..., but I don't know how true that is... You should get your friend to follow you in another car and see if flames come out of your exhaust when this happens...

no way bro, its never perfect that way , hehe someone playing playing tipu u la :D , if got flames it means RICH :) , wasting petrol

its not anti lag system :D

 

[ronniehor]

yeah i understand, many users and mechanics dont know bout it, u r using a Air Flow Sensor fitted cars , u r not supposed to vent out , u r not supposed to use a BOV , u supposed to blow that back into ur intake , once u blow out, the ecu has already got the reading from the MAF that you have AIR , it will still supply fuel and further make the car run rich , and u get a POP , u r lucky enuff that ur car doesnt die off, some ppl face die off , this scenario only happens when u shift gears or cruise on the highway and while u lift off ur accelerator, the bov opens up

yup.....im support your topic.

 

[TurtleV10]

my rear bumper.. is black. on one side. LOL

 

[xinghonh]

im facing the same prob as u wid my 4g93 bot
but mine the pop sound level is not really that loud

 

[D-IV]

aiyah... just take out the spark plugs and see whether all black or looks normal or even white. I doubt you'll have time to look at your rear and notice black smokes when you're already at high RPM pressing the pedal. PLus, normally it won't be noticeable by the driver, people following your rear might notice it though. Normally this occurs if you use aftermarket full exhaust system.