bad fuel mileage and exaust popping - Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum

95civicEX · 07-27-2002, 12:24 AM

I just got my 89 240 a little over a month and a half ago, and have already replaced the cat back with an apexi n1 unit, before I replaced the exaust, and now that it's been done, if I rev the motor, it will randomly pop, the car also does this on occasion if I'm cruising and let off the gas and just let the car slow down in gear...is this a bad thing and could this be related to my next problem?

My fuel mileage is terrible, I just filled the car up today - 10 gallons at 170 miles, I know I'm ragging on the car a bit, but this is horrible, my civic used to get 300 miles per fillup, and that was only around 10 or 11 gallons...

any ideas, I've changed the oil, and used fuel injector cleaner for the past two tanks, and have noticed no difference at all...

thanks for any help in advance

oh yeah, almost forgot, the car is an 89, original motor with 130,000+ miles, the sr20det will go in eventually but for now I've gotta get this motor running better

Tyler Durdan · 07-27-2002, 12:28 AM

As for the popping, it could be a crack in your exhaust manifold.  Someone else might know better though.

As for the bad fuel mileage...try replacing the fuel filter.  I've heard on occasion of this fixing the problem.

tnord · 07-27-2002, 01:21 AM

you're running too rich. why? could be hundreds of things, but at least you have a starting point.

HKrpS13 · 07-27-2002, 04:02 AM

popping sound is back-fire. Good, bad, I don't know.
Please do not compare with Civics on the gas mileage because they are very high.

tnord · 07-27-2002, 09:52 AM

hmmm.......i suppose i should've read your post instead of just the title. Apexi N1 duals have been known to backfire. it's because their piping is too large.........i think. but yeah, drive normally for the next 10 gallons and you should be in the mid 20mpg range.

RoNx777 · 07-27-2002, 10:07 AM

I'm having the same problem w/ my N1 cat-back, when i cruise @ 2500 - 3000 RPM, then pull off from the gas, i hear the back fire. However i had the exhaust for about 3-4 months, and i jus notice it now, not too sure was it there from the beginning.

Da808aZnRaVr · 07-28-2002, 04:48 AM

actually yeah i have the apex n1 and my exhaust makes that poppin noise too when i let off the gas...have had the exhaust for bout a year now and its been doin that ever since...i dont think its a problem or anythin..actually i kinda like that noise...my friends also have n1's on thier cars and they too have that poppin noise...so i wouldnt worry bout the noise...

95civicEX · 07-28-2002, 12:57 PM

alright, I've checked the car out, and after seeing the air filter,which was disgusting, I've replaced it, the car is running rich as there is a nice black spot on the bottom of my bumper where the exaust comes out, so what can cause this and how can I fix it? thanks for any help in advance.

*sykikchimp* · 07-28-2002, 02:22 PM

o2 sensor, and spark plugs would be were I would start..

I started getting crappy mpg after I installed my exhaust and then I realized I was just running the car a lot harder b/c it's fun to listen to the exhaust...

bing · 07-28-2002, 04:52 PM

same problem...

did the o2 sensor, and sparks and wires recently. no difference. i'll try the fuel filter.

also, i like the noise kinda, but the exhaust sounds better when it doesnt pop.

98SilviaS14 · 07-29-2002, 12:23 AM

what's all this i always hear about the backfiring on the dual n1's. i have had mine on for a while now and it runs smooth as silk, so to speak.  actually i was pleasantly surprised cuz i thought that mine was gonna do that when i did the install, but so far so good.

07-27-2002, 12:28 AM	#2
Tyler Durdan Zilvia Junkie Join Date: Feb 2002 Location: Don't mess with Texas Posts: 546 Trader Rating: (0) Feedback Score: 0 reviews	As for the popping, it could be a crack in your exhaust manifold.  Someone else might know better though. As for the bad fuel mileage...try replacing the fuel filter.  I've heard on occasion of this fixing the problem. __________________ "Pure adrenaline attached to a license plate.  Isn't it time to experience one yourself?"                           -Dan Gurney Turbo for Sale

07-27-2002, 10:07 AM	#6
RoNx777 Zilvia Member Join Date: Dec 2001 Posts: 252 Trader Rating: (0) Feedback Score: 0 reviews	I'm having the same problem w/ my N1 cat-back, when i cruise @ 2500 - 3000 RPM, then pull off from the gas, i hear the back fire. However i had the exhaust for about 3-4 months, and i jus notice it now, not too sure was it there from the beginning. __________________ Master Of The Curve. Ruler Of The Twist. Emperor Of Then Hairpin Turn.

07-28-2002, 04:48 AM	#7
Da808aZnRaVr Zilvia Member Join Date: Jan 2002 Location: hawaii Age: 42 Posts: 153 Trader Rating: (0) Feedback Score: 0 reviews	actually yeah i have the apex n1 and my exhaust makes that poppin noise too when i let off the gas...have had the exhaust for bout a year now and its been doin that ever since...i dont think its a problem or anythin..actually i kinda like that noise...my friends also have n1's on thier cars and they too have that poppin noise...so i wouldnt worry bout the noise... __________________ 95 240sx SE,custom dual apex n1, 17" rims,tanabe sustec front STB,nismo rear STB,intake,tanabe sustec pro coilovers,autometer guages, soon to have stock 97-98 side skirts and rear mud guards and bomex drift wing

07-28-2002, 02:22 PM	#9
sykikchimp WOW addicted Join Date: Dec 2001 Location: the moon Age: 44 Posts: 6,525 Trader Rating: (0) Feedback Score: 0 reviews	o2 sensor, and spark plugs would be were I would start.. I started getting crappy mpg after I installed my exhaust and then I realized I was just running the car a lot harder b/c it's fun to listen to the exhaust... __________________

07-28-2002, 04:52 PM	#10
bing Post Whore! Join Date: Oct 2001 Location: ontario canada Posts: 2,699 Trader Rating: (21) Feedback Score: 21 reviews	same problem... did the o2 sensor, and sparks and wires recently. no difference. i'll try the fuel filter. also, i like the noise kinda, but the exhaust sounds better when it doesnt pop. __________________ www.son240sx.org /// www.nyspeed.com

07-27-2002, 12:24 AM	#1
95civicEX Zilvia Member Join Date: Jun 2002 Location: Silver Spring, MD Age: 42 Posts: 196 Trader Rating: (0) Feedback Score: 0 reviews	I just got my 89 240 a little over a month and a half ago, and have already replaced the cat back with an apexi n1 unit, before I replaced the exaust, and now that it's been done, if I rev the motor, it will randomly pop, the car also does this on occasion if I'm cruising and let off the gas and just let the car slow down in gear...is this a bad thing and could this be related to my next problem? My fuel mileage is terrible, I just filled the car up today - 10 gallons at 170 miles, I know I'm ragging on the car a bit, but this is horrible, my civic used to get 300 miles per fillup, and that was only around 10 or 11 gallons... any ideas, I've changed the oil, and used fuel injector cleaner for the past two tanks, and have noticed no difference at all... thanks for any help in advance oh yeah, almost forgot, the car is an 89, original motor with 130,000+ miles, the sr20det will go in eventually but for now I've gotta get this motor running better

07-27-2002, 01:21 AM	#3
tnord Nissanaholic! Join Date: Dec 2001 Posts: 1,975 Trader Rating: (0) Feedback Score: 0 reviews	you're running too rich. why? could be hundreds of things, but at least you have a starting point.

07-27-2002, 04:02 AM	#4
HKrpS13 Zilvia Member Join Date: Dec 2001 Location: SoCal Posts: 267 Trader Rating: (0) Feedback Score: 0 reviews	popping sound is back-fire. Good, bad, I don't know. Please do not compare with Civics on the gas mileage because they are very high.

07-27-2002, 09:52 AM	#5
tnord Nissanaholic! Join Date: Dec 2001 Posts: 1,975 Trader Rating: (0) Feedback Score: 0 reviews	hmmm.......i suppose i should've read your post instead of just the title. Apexi N1 duals have been known to backfire. it's because their piping is too large.........i think. but yeah, drive normally for the next 10 gallons and you should be in the mid 20mpg range.

07-28-2002, 12:57 PM	#8
95civicEX Zilvia Member Join Date: Jun 2002 Location: Silver Spring, MD Age: 42 Posts: 196 Trader Rating: (0) Feedback Score: 0 reviews	alright, I've checked the car out, and after seeing the air filter,which was disgusting, I've replaced it, the car is running rich as there is a nice black spot on the bottom of my bumper where the exaust comes out, so what can cause this and how can I fix it? thanks for any help in advance.

07-29-2002, 12:23 AM	#11
98SilviaS14 Join Date: Aug 2001 Posts: 37 Trader Rating: (0) Feedback Score: 0 reviews	what's all this i always hear about the backfiring on the dual n1's. i have had mine on for a while now and it runs smooth as silk, so to speak.  actually i was pleasantly surprised cuz i thought that mine was gonna do that when i did the install, but so far so good.