Sr20 Lean in boost/idle problem - Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum

Jasonx63 · 03-16-2012, 03:53 AM

Ive searched the forum and done the recommended things with no luck.

a couple days ago i started my car and the idle was jumpy i mean it'd idle at 1.1k solid then drop and my boost gauge would read like i had a leak 10-14inhg so i did a boost leak test and found some small ones and fixed them. the problem remains. ive also adjusted the TPS to perfect voltage readings check plugs fuel pressure changed o2 and i have split fire coilpacks so im sure those are fine. when it idles at 1100rpms afrs are good and vacuum reads good then when it drops to 800ish goes lean 17ish for a couple seconds(only does this when cold) and goes back up fine. when im crusing afrs are perfect 14.1-14.9 it richens when i accelerate and even when i floor the car UNTIL it reaches full boost. ive tried everything i can think of any advice would help,Thanks.

s13 blacktop 740cc inj,225walbro, z32maf,z32 fuel filter,bkr7e gapped at .028, nismo fpr with fuel pressire reading 45.0 also have used my aeromotive fpr with no difference made.

TLTR
- idles a little jumpy boost gauge occasionally reads as if i had a leak when ive tested for one several times and isnt any.
-Afrs while cruising are 14.0-14.9
-afrs in full boost are really really lean

Croustibat · 03-16-2012, 04:13 AM

check the voltage at the fuel pump, the wires are know to be a bit too thin for high flow pumps. As soon as they start to wear, they pump too much current and voltage drops, resulting in higher flow loss.

How old is your fuel filter ?
How old is the fuel pump ( it could be defective too )
Did you get a tune ? I guess so as you have bigger injectors and maf but you might have gone lucky and get a somewhat working setup...

my bet is on a fuel filter/fuel pump/injector gaskets problem though.

Jasonx63 · 03-16-2012, 04:21 AM

the pump is around 6 months old will check voltages in the morning filter a couple months, and yes ecu tuned by efi specialist and keep in mind this car was running perfect for 5 months as a daily driver.

KiLLeR2001 · 03-16-2012, 06:24 AM

What turbo? How much boost are you pushing out? Wastegate working properly? How is your vacuum system routed?

Is this on an S13 chassis? If so, did you block off your gas tank venting line? You need leave the vent open as positive pressure will build up in the tank and will cause premature failure of the fuel pump unit. If you did block the vent line, you can use an S14 gas cap as it is a 2-way valve unlike the S13 cap which is only a one way valve (vacuum). If you didn't block the vent line, you may need to check the fuel check valve (little black cannister thing) that runs from the tank to the vent line, if its no longer functional you will build up pressure in the tank. An easy way to tell if you have pressure building up is if you go for a drive and then unscrew your gas cap, if a surge of air comes rushing out that is usually a sign of a faulty fuel check valve OR a blocked vent line.

http://www.courtesyparts.com/17330-v...4-p-65084.html

Jasonx63 · 03-16-2012, 02:08 PM

It's a 95 s14, Turbo is gt2871r .86 14psi crusing 18psi for fun. I'll check that today. I'll take a picture.of my vacuum set up

Jasonx63 · 03-16-2012, 06:34 PM

here are some pictures of the vacuum lines and the bay in general any help would be awesome. i was wondering if it could be the sensor for my afr gauge because if my car was hitting boost at 18 or higher on the afr gauge wouldnt it sputter or even probably blow up?? i mean when it boost it feels just like it always has for the past 6 months or more of driving. any thoughts??? thanks

*StryfeS13* · 03-17-2012, 12:17 AM

Well there's the problem....you bought one of those purple-top SR20s...

shoulda got a blacktop

mktachibana · 03-17-2012, 12:31 AM

jesus thats a mess. It's hard to see all your lines but it looks like you branched your fuel pressure regulator. It should have it's own vacuum source and i cant really see where it all goes to it disappears behind your engine.

KiLLeR2001 · 03-17-2012, 01:05 AM

Yeah it may be a sensor issue. Everything looks good except for the FPR. Try to get it on its own vacuum source. Use the left port strictly for the FPR. The right port is bigger so you can T that off for the BOV + whatever else you have there.

Jasonx63 · 03-18-2012, 01:43 AM

ok so today i changed the vacuum sources up to how you guys said. and it didnt really make a change. any other suggestions? i bought at a tps at a good price just in case mine was bad. i am also thinking of buying a new walbro pump from my research they are prone to going bad but first im going to test it tomorrow. also could this be a maf problem? ive tried cleaning it and such just havent been able to get ahold of one to test it with.

03-16-2012, 03:53 AM	#1
Jasonx63 Zilvia Member Join Date: Aug 2010 Location: Fresno Age: 34 Posts: 225 Trader Rating: (2) Feedback Score: 2 reviews	Sr20 Lean in boost/idle problem Ive searched the forum and done the recommended things with no luck. a couple days ago i started my car and the idle was jumpy i mean it'd idle at 1.1k solid then drop and my boost gauge would read like i had a leak 10-14inhg so i did a boost leak test and found some small ones and fixed them. the problem remains. ive also adjusted the TPS to perfect voltage readings check plugs fuel pressure changed o2 and i have split fire coilpacks so im sure those are fine. when it idles at 1100rpms afrs are good and vacuum reads good then when it drops to 800ish goes lean 17ish for a couple seconds(only does this when cold) and goes back up fine. when im crusing afrs are perfect 14.1-14.9 it richens when i accelerate and even when i floor the car UNTIL it reaches full boost. ive tried everything i can think of any advice would help,Thanks. s13 blacktop 740cc inj,225walbro, z32maf,z32 fuel filter,bkr7e gapped at .028, nismo fpr with fuel pressire reading 45.0 also have used my aeromotive fpr with no difference made. TLTR - idles a little jumpy boost gauge occasionally reads as if i had a leak when ive tested for one several times and isnt any. -Afrs while cruising are 14.0-14.9 -afrs in full boost are really really lean

03-16-2012, 06:24 AM	#4
KiLLeR2001 Post Whore! Join Date: Jun 2007 Location: オーランドフロリダ Posts: 7,955 Trader Rating: (46) Feedback Score: 46 reviews	What turbo? How much boost are you pushing out? Wastegate working properly? How is your vacuum system routed? Is this on an S13 chassis? If so, did you block off your gas tank venting line? You need leave the vent open as positive pressure will build up in the tank and will cause premature failure of the fuel pump unit. If you did block the vent line, you can use an S14 gas cap as it is a 2-way valve unlike the S13 cap which is only a one way valve (vacuum). If you didn't block the vent line, you may need to check the fuel check valve (little black cannister thing) that runs from the tank to the vent line, if its no longer functional you will build up pressure in the tank. An easy way to tell if you have pressure building up is if you go for a drive and then unscrew your gas cap, if a surge of air comes rushing out that is usually a sign of a faulty fuel check valve OR a blocked vent line. http://www.courtesyparts.com/17330-v...4-p-65084.html __________________

03-17-2012, 01:05 AM	#9
KiLLeR2001 Post Whore! Join Date: Jun 2007 Location: オーランドフロリダ Posts: 7,955 Trader Rating: (46) Feedback Score: 46 reviews	Yeah it may be a sensor issue. Everything looks good except for the FPR. Try to get it on its own vacuum source. Use the left port strictly for the FPR. The right port is bigger so you can T that off for the BOV + whatever else you have there. __________________

03-16-2012, 04:13 AM	#2
Croustibat Nissanaholic! Join Date: Aug 2011 Location: France - Toulouse Age: 44 Posts: 1,851 Trader Rating: (0) Feedback Score: 0 reviews	check the voltage at the fuel pump, the wires are know to be a bit too thin for high flow pumps. As soon as they start to wear, they pump too much current and voltage drops, resulting in higher flow loss. How old is your fuel filter ? How old is the fuel pump ( it could be defective too ) Did you get a tune ? I guess so as you have bigger injectors and maf but you might have gone lucky and get a somewhat working setup... my bet is on a fuel filter/fuel pump/injector gaskets problem though.

03-16-2012, 04:21 AM	#3
Jasonx63 Zilvia Member Join Date: Aug 2010 Location: Fresno Age: 34 Posts: 225 Trader Rating: (2) Feedback Score: 2 reviews	the pump is around 6 months old will check voltages in the morning filter a couple months, and yes ecu tuned by efi specialist and keep in mind this car was running perfect for 5 months as a daily driver.

03-16-2012, 02:08 PM	#5
Jasonx63 Zilvia Member Join Date: Aug 2010 Location: Fresno Age: 34 Posts: 225 Trader Rating: (2) Feedback Score: 2 reviews	It's a 95 s14, Turbo is gt2871r .86 14psi crusing 18psi for fun. I'll check that today. I'll take a picture.of my vacuum set up

03-16-2012, 06:34 PM	#6
Jasonx63 Zilvia Member Join Date: Aug 2010 Location: Fresno Age: 34 Posts: 225 Trader Rating: (2) Feedback Score: 2 reviews	here are some pictures of the vacuum lines and the bay in general any help would be awesome. i was wondering if it could be the sensor for my afr gauge because if my car was hitting boost at 18 or higher on the afr gauge wouldnt it sputter or even probably blow up?? i mean when it boost it feels just like it always has for the past 6 months or more of driving. any thoughts??? thanks

03-17-2012, 12:31 AM	#8
mktachibana Leaky Injector Join Date: Mar 2010 Location: in my house Age: 37 Posts: 98 Trader Rating: (0) Feedback Score: 0 reviews	jesus thats a mess. It's hard to see all your lines but it looks like you branched your fuel pressure regulator. It should have it's own vacuum source and i cant really see where it all goes to it disappears behind your engine.

03-18-2012, 01:43 AM	#10
Jasonx63 Zilvia Member Join Date: Aug 2010 Location: Fresno Age: 34 Posts: 225 Trader Rating: (2) Feedback Score: 2 reviews	ok so today i changed the vacuum sources up to how you guys said. and it didnt really make a change. any other suggestions? i bought at a tps at a good price just in case mine was bad. i am also thinking of buying a new walbro pump from my research they are prone to going bad but first im going to test it tomorrow. also could this be a maf problem? ive tried cleaning it and such just havent been able to get ahold of one to test it with.