Forums/Z31P/z31-repairs-forums engine-mechanical/Boost problems
Imported from Z31Performance.com Forums{{#if:barkrz18| — original post by barkrz18}}{{#if:2010-04-27 13:01:45|, posted 2010-04-27 13:01:45}}{{#if:20| · 20 post{{#ifeq:20|1||s}}}}{{#if:/Z31performance_archive/forum/z31-repairs-forums/engine-mechanical/10326-boost-problems.html|
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barkrz18: (2010-04-27 13:01:45)
I have installed a few upgrades to wind the boost up
Following mods - Walbro fuel pump
Malpassi fpr
near new stock injectors
Profec spec b boost controller
new leads and plugs
new water pump and timing belt
I have turned the fuel pressure up to 42psi and i think stock was 36. I turned the boost up on the controller also and when i took it for a drive i noticed the once it went over 11psi it would start lagging and not boosting properley. i have read up about whinding boost up and i was sure i done everything correct.
anyone know if i am missing something?
BLOZ UP: (2010-04-27 13:03:50)
Not boosting properly? Gap too high? Although, at 11psi, I doubt it.
barkrz18: (2010-04-27 13:16:30)
shouldnt the gap on plugs be right since the are new? it feels real good up until it goes over 10 psi and it starts running sluggish and lagging heaps.
Would my lifters ticking hard be the reason why this could be happening?
Tempestas: (2010-04-27 14:14:59)
considering you listed everything else… do you still have a pop off valve installed? That would open up, dump the air, cause excessive rich condition…
sprtcrazy17: (2010-04-27 19:24:47)
It wouldn't go over 8psi if that were the case. I wouldn't run over 10psi without an intercooler personally. I've seen bad things happen.
What plugs did you install? Stock NGK should be used
BLOZ UP: (2010-04-27 20:09:43)
They are usually pre-gapped, but I always check before I pop them in.
I was wondering if you were blowing sparks out. I doubt it, but it's possible. So, either that, or it's running too lean or rich. I would find out before you try it again.
DMANN: (2010-04-27 21:11:36)
Lifters ticking hard??? Sounds like detonation! You upgraded the fuel pump but not the injectors?
Whats the timing set at!
I can't run past 9psi on my stock 87t before it starts running lean, and starts to denonate!
Just a thought.
Mitchd03: (2010-04-28 05:25:28)
Get an intercooler.
In fact, take a video of it so we can see what happens 1st hand.
Robyr: (2010-04-28 07:37:24)
I am having a hard time believing his motor is detonating at 11psi. There has to be an underlying cause if it is, because no VG ive ever had cared about 10ish psi. I'd still STRONGLY suggest looking at your fuel, and any vacuum leaks as that would definitely not help you.
nismopu: (2010-04-28 18:18:22)
Mine did this as well for a short bit and it tunred out to be the factory POP off valve bleeding off. Lower you spark gap and get a wideband. Won't have to worry about guessing what's up as much.
Steve88t: (2010-04-28 18:54:34)
You turned up the base fuel pressure by 6 psi. I'd guess considering the very conservative tuning of the stock ecu that you're running too rich at that point. You might consider returning the fuel pressure and boost to stock levels and evaluate performance then. If the car runs perfect you know it is related to one of the two and that there are not other problems with the car. Then you diagnose accordingly.
barkrz18: (2010-04-29 11:18:54)
oh sorry i forgot to mention intercooler with hks bov.
The stock releif valve has been blocked off.
i also have a fuel pressure gauge.
and when it goes over 11psi it starts lagging in speed
Careless: (2010-05-02 22:12:56)
have to say, i reduced my fuel pressure because it was wayyyyyyyyyyyyyyy higher than factory, and then i blocked off the intake filter with some cardboard to test it's temperature sensitivity.
runs much cooler and much better than it ever did.
14Psiplease: (2010-05-02 22:35:51)
Have you setup you BOV properly? 11psi+ could be to much for you bov if it isnt adjusted correctly. Try increasing the spring tension.
BLOZ UP: (2010-05-02 22:47:20)
The spring tension only affects operation under vacuum. The spring has to be stronger than the engine's vacuum. Boost pressure and the spring keep it closed otherwise.
14Psiplease: (2010-05-03 01:31:37)
im not sure how the hks ones are designed But i thought the spring keeps the valve shut cause boost pressure is trying to push it open and when you close throttle the engine vacuum plus the boost pressure combined help over come the spring tension to allow it to open concluding why it so important to adjust it or it will stay shut, not blow off or be open during boost leaking air to the atmosphere.
BLOZ UP: (2010-05-03 03:11:03)
When under boost, pressure on the valve and pressure on the diaphragm are about the same. The spring keeps it shut, but it doesn't take a lot of spring pressure to do this.
When under no boost, there's little to no vacuum against the valve and a lot of vacuum on the diaphragm (after the throttle body). The spring's main purpose is to keep it shut here.
But, after releasing the throttle from boosting, the spring has to be weak enough to allow enough boost to escape.
So, you're still right. But not because of boost. It might be leaking under vacuum. If the BOV is setup for X psi correctly, it's setup for Y psi correctly. Most of the time.
14Psiplease: (2010-05-03 05:32:57)
Ahh i see equal pressure on both sides of the valve so its like theirs no pressure at all.
barkrz18: (2010-05-03 13:30:51)
The hks bov has no adjustment just a vaccum line running off it. i did have an adjustable bov but that wasnt helping much. The bov that is installed is not leaking at all.
Ive replaced the lifters and about to replace oil. im going to use %100 synthetic oil is this ok to use?
also just replaced the injector wiring and a rebuild kit installed on all injectors and the intake plenum gasket in case for leaks.
i have also gone over the inter cooler piping for leaks and everything seems to be ok.
also when boosting over 8psi it sounds like it has a 2nd spooling noise, I've heard this once before when the boost line coming off turbo has split. i haven't checked this yet but it could be another problem that i cant solve
barkrz18: (2010-05-10 13:07:26)
the zed is missing a little when take off sometimes and when i put my foot flat it seems to miss before hitting desired boost then if i back off and boost again it hits desired psi fine.