Running lean + backfire - Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum

playastarkz123 · 08-05-2008, 04:04 PM

OK so heres the deal. When i start up my car with the engine cool (left overnight) it normally starts right up and idles smoothly with an afr at about 14.1 to 14.8. IT drives smoothly too until the engine warms up. Then i get a extremely lean idle higher than 18 where my aem wideband just displays three dashes across it. At this time the car also begins to idle roughly and stalls. Under partial throttle it sputters and on the deceleration it backfires and shoots flames alot. however once i punch the throttle afr's are normal 10.8-11.6 and it accelerates smoothly. But once i begin to idle again the problem continues. i pulles a code from the ecu and it was 1 3 which i believe is CTS, when i changed it, i still got the same code.

if it helps my mods are : redtop sr20det, stock t25, FMIC, megan racing manifold, 3" dp (no flex pipe), 3" apexi N1 catback, megan racing FPR, walboro 255 lph, SAFC (tuned @ ivey tune) boost at 14 lbs via halman MBC, koyo radiator, turbo XS RFL bov, z32 maf

so far:
i have set the timing at 15 degrees BTDC according to FSM
changed coolant temp sensor
changed fuel filter
set Decel air settings on SAFC (to compensate for atmospheric BOV)
checked visually for vaccum leaks
changed valve cover and spark plug gaskets
set IACV

also at WOT i am not losing boost. ANY input would be appreciated

1989rps13 · 08-05-2008, 04:22 PM

damn i experience the same thing with mine

aa87 · 08-05-2008, 04:45 PM

Check gas tank, fuel pump sock might be clogged in shit.

SixSpeedSleuth · 08-05-2008, 05:22 PM

What's your base fuel pressure?

codyace · 08-05-2008, 05:38 PM

have you pressure tested your setup?

what about taking the SAFC out of the equation alltogether, and then seeing how she works?

playastarkz123 · 08-05-2008, 07:09 PM

my fuel pressure is right around 43 psi @ idle

no i havent, i have a pressure tester and an air compressor but the tester doesnt fit on my intake pipe, i guess ill have to buy a reducing coupler to make it fit

ill also take out my fuel pump and take a look at the sock, how often should these be replaced/cleaned

as for the suggestion about the safc, do you mean set everything to zero % correction? wouldnt that definately cause me to run lean?

makulit054 · 08-05-2008, 07:44 PM

check your TPS voltage. I adjusted my tps voltage to .5v at idle it doesn't sputter or backfire. Another good idea is to recirc your bov. That will solve most of your sputtering and backfiring during deceleration.

*fliprayzin240sx* · 08-05-2008, 08:21 PM

hmmm, changed stock o2 sensor yet?

codyace · 08-05-2008, 09:31 PM

Quote:

Originally Posted by playastarkz123

my fuel pressure is right around 43 psi @ idle

no i havent, i have a pressure tester and an air compressor but the tester doesnt fit on my intake pipe, i guess ill have to buy a reducing coupler to make it fit

ill also take out my fuel pump and take a look at the sock, how often should these be replaced/cleaned

as for the suggestion about the safc, do you mean set everything to zero % correction? wouldnt that definately cause me to run lean?

I mean take the SAFC out all together.

playastarkz123 · 08-06-2008, 10:06 AM

Quote:

Originally Posted by codyace

I mean take the SAFC out all together.

ohh ok ill try that this afternoon,

I have changed the stock 02 sensor too, forgot to include that in the OP

playastarkz123 · 08-06-2008, 08:35 PM

So i went and took a look at the fuel pump sock. its a little brown. I took it out and poured water on it to see how clogged it was, and i guess it was somewhat cloggy but not alot, i guess ill change it and see what happens though. heres some pics

ohh yea and while i was doin that i F'ed up my the 0-ring gasket

, now gas spills when ever the car is on, so ill be on my way to the dealership in the morning to fix that. heres a pic of that

ROIDMONKEY · 08-06-2008, 08:47 PM

same happened to me with theO ring. i cut it evenly and stretched a bit then i apply clear silicone. that solved my o ring problem. i did it that way cause it was friday. otherwise i would it get a new one. its holding pretty good. over 2 months

and on the other problem u r having, something similar is happening to me but the other way. im having cold start problems. car cold cars iddle very bad wideband display 000 or ---- lean as fuck. cars get warm then cars fix himself . we didnt run the in and out hoses on the throttle body on this setup just to get away of the hot air going inside manifold (from hot water) but i cant take this cold start problem anymore so im going to connect those water hoses tomorrow and see if it fix the cold start problem.

Quote:

Originally Posted by playastarkz123

So i went and took a look at the fuel pump sock. its a little brown. I took it out and poured water on it to see how clogged it was, and i guess it was somewhat cloggy but not alot, i guess ill change it and see what happens though. heres some pics

ohh yea and while i was doin that i F'ed up my the 0-ring gasket

, now gas spills when ever the car is on, so ill be on my way to the dealership in the morning to fix that. heres a pic of that

08-05-2008, 04:04 PM	#1
playastarkz123 Zilvia Junkie Join Date: Apr 2007 Location: New Jersey Age: 34 Posts: 328 Trader Rating: (8) Feedback Score: 8 reviews	Running lean + backfire OK so heres the deal. When i start up my car with the engine cool (left overnight) it normally starts right up and idles smoothly with an afr at about 14.1 to 14.8. IT drives smoothly too until the engine warms up. Then i get a extremely lean idle higher than 18 where my aem wideband just displays three dashes across it. At this time the car also begins to idle roughly and stalls. Under partial throttle it sputters and on the deceleration it backfires and shoots flames alot. however once i punch the throttle afr's are normal 10.8-11.6 and it accelerates smoothly. But once i begin to idle again the problem continues. i pulles a code from the ecu and it was 1 3 which i believe is CTS, when i changed it, i still got the same code. if it helps my mods are : redtop sr20det, stock t25, FMIC, megan racing manifold, 3" dp (no flex pipe), 3" apexi N1 catback, megan racing FPR, walboro 255 lph, SAFC (tuned @ ivey tune) boost at 14 lbs via halman MBC, koyo radiator, turbo XS RFL bov, z32 maf so far: i have set the timing at 15 degrees BTDC according to FSM changed coolant temp sensor changed fuel filter set Decel air settings on SAFC (to compensate for atmospheric BOV) checked visually for vaccum leaks changed valve cover and spark plug gaskets set IACV also at WOT i am not losing boost. ANY input would be appreciated __________________ www.teamirrational.wordpress.com Last edited by playastarkz123; 08-05-2008 at 07:11 PM..

08-05-2008, 04:45 PM	#3
aa87 Zilvia FREAK! Join Date: May 2003 Location: Shreveport, LA Age: 36 Posts: 1,116 Trader Rating: (1) Feedback Score: 1 reviews	Check gas tank, fuel pump sock might be clogged in shit. __________________ Hookers and blow.

08-05-2008, 05:38 PM	#5
codyace Post Whore! Join Date: Dec 2004 Location: Poconos, PA Age: 39 Posts: 8,030 Trader Rating: (58) Feedback Score: 58 reviews	have you pressure tested your setup? what about taking the SAFC out of the equation alltogether, and then seeing how she works? __________________ *Want Air Conditioning in your SR20 Swapped car? Check out www.sr20acbrackets.com for more information! Quest Alternator Conversions for SR20!* Check my Group Buy! Tired of lousy internal gates? Go external wastegate with one of my manifolds, Check out my group buy

08-05-2008, 07:09 PM	#6
playastarkz123 Zilvia Junkie Join Date: Apr 2007 Location: New Jersey Age: 34 Posts: 328 Trader Rating: (8) Feedback Score: 8 reviews	my fuel pressure is right around 43 psi @ idle no i havent, i have a pressure tester and an air compressor but the tester doesnt fit on my intake pipe, i guess ill have to buy a reducing coupler to make it fit ill also take out my fuel pump and take a look at the sock, how often should these be replaced/cleaned as for the suggestion about the safc, do you mean set everything to zero % correction? wouldnt that definately cause me to run lean? __________________ www.teamirrational.wordpress.com

08-05-2008, 08:21 PM	#8
fliprayzin240sx Man w/ CTSV & a Car Seat Join Date: Aug 2002 Location: Tampa Posts: 17,998 Trader Rating: (19) Rides Gallery: fliprayzin240sx Feedback Score: 19 reviews	hmmm, changed stock o2 sensor yet? __________________ If you think Zilvia has too many assholes... CLICK HERE!!!

08-05-2008, 04:22 PM	#2
1989rps13 BANNED Join Date: Sep 2007 Location: socal Posts: 1,499 Trader Rating: (10) Feedback Score: 10 reviews	damn i experience the same thing with mine

08-05-2008, 05:22 PM	#4
SixSpeedSleuth Zilvia Member Join Date: Jul 2007 Location: North Carolina Age: 45 Posts: 176 Trader Rating: (3) Feedback Score: 3 reviews	What's your base fuel pressure?

08-05-2008, 07:44 PM	#7
makulit054 Zilvia Member Join Date: May 2007 Location: socal Posts: 215 Trader Rating: (1) Feedback Score: 1 reviews	check your TPS voltage. I adjusted my tps voltage to .5v at idle it doesn't sputter or backfire. Another good idea is to recirc your bov. That will solve most of your sputtering and backfiring during deceleration.

08-06-2008, 08:35 PM	#11
playastarkz123 Zilvia Junkie Join Date: Apr 2007 Location: New Jersey Age: 34 Posts: 328 Trader Rating: (8) Feedback Score: 8 reviews	So i went and took a look at the fuel pump sock. its a little brown. I took it out and poured water on it to see how clogged it was, and i guess it was somewhat cloggy but not alot, i guess ill change it and see what happens though. heres some pics ohh yea and while i was doin that i F'ed up my the 0-ring gasket , now gas spills when ever the car is on, so ill be on my way to the dealership in the morning to fix that. heres a pic of that __________________ www.teamirrational.wordpress.com