Boost & Idle issue...

[dorkidori_s13]

hi all. thought id post about a few issues im having. please read before commenting

here are my engine specs:
Blacktop (NOT notchtop) SR20det
T28 S15 turbo (which JUST replaced a worn out T25)
Walbro fuel pump
Greddy FMIC
HKS SSQV 3 BOV (authentic, purchased from MVP Motorpsorts)
Greddy PE2 catback
Megan 02 housing and downpipe
7 psi boost (stock boost)
Stock SR turbo manifold (replaced a Megan tubular manifold).


Boost: so as of late, my car seems to be reaching boost kinda late. my car would shrug a bit right before boost hit, but full boost hasnt been hitting until 4000rpms (all 7psi). From what I remember with stock boost, it should be full spool by 3000rpms. I just installed an S15 specR turbo and OEM manifold on saturday. the car has stopped shrugging before boost, but boost still comes on around 4000rpms. I tightened all my clamps and made sure i wasnt leaking boost (used a boost leak tested we made at the shop), no hissing, no leaky pipes. last i remember, an S15 turbo should be at 7psi around 2800rpms due to being dual ball bearing.

Idle: my SR has never had a consistent idle. sometimes it will idle around 800rpms, other times around 1100. a lot of times it will idle around 1100 then drop down to 800-700 range (i backed off the IACV to push the RPMs up around 1000 at idle). even with the new turbo, car still has idle issues. im thinking i might need to clean the IACV out (a lot of FWD SR guys have to do this, especially with bad turbos) or my TPS is going bad.

the T25 i just pulled off the car was leaking oil pretty badly into the hotpipe (it would spray all over the place with my SSQV). i would go thru at least a quart of oil between oil changes because of it. im taking a guess that excess oil build up would gunge up the IACV pretty badly. but as far as late boost goes, im pretty clueless on this one. one thing i could think of it being is that the fuel pump is going bad (though i dont get any knock, ive burned thru quite a few walbros in the past) which is causing a lean condition before boost or my fuel pressure regulator is taking a dump.

input would be much appreciated...also i am going to restate..

DO NOT TELL ME TO TIGHTEN DOWN MY INTERCOOLER CLAMPS, I BOOST LEAK TESTED THE CAR!!! IT IS NOT LEAKING AIR!!

[MrChow]

I've seen it this problem in a car but only had a idle Idk how boost but how pcv hooked up correctly?

[240zach]

as far as the oil in the turbo, is that from the port on the right side of the valve cover? i know if its stock the back will go to an oem oil catch can, and the front would go to the turbo intake..
if thats where the oil is coming from and you know for sure that everything is plugged in and hooked up correctly what you could do to try to stop that is:

by the injectors on the top of the intake mani theres a couple lines all being connected by vacuum lines...ill try and get a pic, but i know if you delete that system and plug it then you won't get oil going outside the right side of the valve cover so there wouldn't necessarily be oil blowing into your turbo..sorry if this doesn't make sense ill try to get a pic in a sec hold on. lol

[KiLLeR2001]

Check your ignition timing. Check your fuel pressure. Is your fuel tank vented properly? Whats your engine management? Hows spark plug gap? What about your vacuum line set up? Recirc BOV?

Need more information, lol.

[240zach]

JDM_Used_Nissan_Silvia_S13_SR20DET_MT by zachj1, on Flickr



okay..the highlighted blue is what I'm talking about. if you remove that. there is no oil that comes out of what I've high lighted green. which goes into your turbo intake and eventually into the turbo...lol

[240zach]

my friend did it and it worked for him.. lol

[dorkidori_s13]

Originally Posted by KiLLeR2001

Check your ignition timing. Check your fuel pressure. Is your fuel tank vented properly? Whats your engine management? Hows spark plug gap? What about your vacuum line set up? Recirc BOV?

Need more information, lol.

ignition timing set to 15 degres TDC (did this a few weeks back), no idea on fuel pressure (no gauge), fuel tank is OEM with the only thing being modified is a drop in walbro, engine management is OEM, spark plug gap is OEM (just replaced them a few weeks back with OEM denso's) vacuum line setup is OEM, no recirc (atmosphere on HKS, but this doesnt make any difference as ive run both recirc and non recirc with the same results in idle and boost issues)

the motor is pretty much stock outside of a few minor bolt ons. its not some fully built race car setup. its my daily driver/restoration project so the car isnt beat on.

[KiLLeR2001]

You'll want to check your fuel pressure, also make sure you didn't cap off your fuel tank vent line (if you removed the charcoal canister). Easiest way to tell if your tank isn't being vented properly is when you go to the gas station and open the cap, it'll make the "psshhhhh" noise releasing pressurized air.

You can pull your plugs to see if they indicate a lean running condition.

Do you have a vacuum hose routed back to a catch can and then to intake after MAF to relieve some of the positive pressure in the crankcase?

If all this checks out you may want to pull the IACV for further inspection.

Also check to make sure your CTS is within spec, irregularities with voltage output of the CTS can cause a higher/irregular idle.

[dorkidori_s13]

Originally Posted by KiLLeR2001

You'll want to check your fuel pressure, also make sure you didn't cap off your fuel tank vent line (if you removed the charcoal canister). Easiest way to tell if your tank isn't being vented properly is when you go to the gas station and open the cap, it'll make the "psshhhhh" noise releasing pressurized air.

You can pull your plugs to see if they indicate a lean running condition.

Do you have a vacuum hose routed back to a catch can and then to intake after MAF to relieve some of the positive pressure in the crankcase?

If all this checks out you may want to pull the IACV for further inspection.

Also check to make sure your CTS is within spec, irregularities with voltage output of the CTS can cause a higher/irregular idle.

ill check the plugs later today when i get home

all vacuum lines are routed properly and so are oil circulation lines from the crank case. only thing removed was the OEM oil catch tank that hangs near the rear of the valve cover (i never had it hooked up on my last SR and it ran fine for 8 years without a hitch)

gas can vent thing in engine bay is not plugged (i removed the charcoal canister, ive never un one). get plenty of gas tank hiss.

im planning on pulling the IACV soon. gonna get a plastic manifold spacer as well as new fuel injectors, new fuel rail and FPR. i plan on going after the intake manifold with a TON of B12 to get it all cleaned up (i know theres a pool of old nasty oil sitting in there). IACV will be taken apart and cleaned like whoa.

ill see what i cant do about getting a multimeter and checking out the voltage on both the CAS and TPS. i know if the TPS isnt set with the right voltage, idle sucks on an SR

[dorkidori_s13]

plugs arent fouled, though there are carbon deposits on the base of the plugs (where the threads are), no burining or scortching on them. no oil on them either (thank god).

i get a nasty feeling my walbro is going to shit out on me soon...ive had 4 of them in the past, nothing but problems (especially out here in vegas). i swore i would never own one again, but low and behold, its what came with the car. think it might be time to call MVP about a denso supra TT pump (nothing like good ol oem that handles 500+ whp)

[KiLLeR2001]

Is the Walbro making a loud whining noise? When mine started to go it was very audible and annoying after about 10 minutes of driving. My idle was rough and I was only getting 32psi at idle with stock FPR (which was a good working FPR).

I told myself if this new Walbro I bought goes bad I'm buying a Z32 TT OEM pump and be done with Walbro's for good...

PUMP ASSY-FUEL - 300ZX (Z32) 1990-1996 Turbo :: Nissan Parts, NISMO and Nissan Accessories - Courtesyparts.com

[dorkidori_s13]

walbros are always loud, i just know they dont like to hold up to vegas heat. my first one lasted me a few years, then the next 3 were between 4 months to a year at most. theyre pieces of shit (its why theyre so cheap). gonna head to the shop HOPEFULLY tomorrow and start diagnosing this shiet. i just want a stock boost SR that runs without hiccups oi

[KiLLeR2001]

My current Walbro is silent as a mouse. And when I originally bought my old one it was silent as well. Once it got loud, that's when I started noticing problems.

[dorkidori_s13]

yeah mine is getting fairly loud now. i think first pay check in june im gonna grab a denso TT pump and wire it up (just need to move the battery to ye olde trunk and wire up a resistor)

[mr2gons14]

I have an hks idle stabilizer that worked wonders for me. Upgraded to a pfc and it fixed all problems the hks is a cheap solution lemme know i got it up for grabs

[dorkidori_s13]

nah, im good. my motor shouldnt have idle issues given is mostly stock (nothing thats on the motor should be causing idle issues either), thanks though.

[mr2gons14]

well if u find urself in need lemme know other than that besta luck I also gotta 300zx tt fuel pump if u burn through another walbro.

[dorkidori_s13]

im just gonna pick up a denso supra pump. they work like champs in the S13 and match the length of the OEM pump perfectly.

[mr2gons14]

aight well lemme know if u need anythin ill give it to u 50 bucks shipped