Boost leak?

[So Make Like]

WOT at about 5000 rpm I reach a "wall" or something of the like. Or more like a bogging, actually. As I gradually let off the throttle I can feel the car sort of lunge forward as it tapers out of boost. My boost gauge reads only about 3-4 psi and the needle kind of flutters. Boost leak? Fouled plugs?

[ultimateirving]

Boost leak most likely. But why make a post?
just pressure test it to rule it out

[So Make Like]

I would if I had access to a compressor, for sure. :(

[milto0n]

I've heard of people using bike pumps on their boost leak testers. If you don't have anything, remove boost piping as close to the turbo as possible and blow with your mouth. That should be good for finding any major leaks.

[Dboyizmlg]

Check your air filter. Make sure it's too beat up, or old....
Replace if needed

[Mikester]

Check your WG actuator... cycle the rod open/closed manually. If it's stupid-easy to actuate, that's a great sign it needs to be replaced.

ALso, if you used any type of fuel system cleaner, octane booster etc- then it's your plugs. That stuff cooks SR/RB plugs. Also always run 91-93 or higher octane.

[ultimateirving]

Check your WG actuator... cycle the rod open/closed manually. If it's stupid-easy to actuate, that's a great sign it needs to be replaced.

ALso, if you used any type of fuel system cleaner, octane booster etc- then it's your plugs. That stuff cooks SR/RB plugs. Also always run 91-93 or higher octane.

Lol mike, you really hate that shit huh?
I never ran any, but it humors me how you make sure every newb knows. Carry on!

[Mikester]

^^No, I don't hate it at all... I ran it in my GT-R... then once I got to less than 1/2 tank, the car would start to hesitate/buck under load, then smooth out if I backed off a bit... I chased my fucking tail trying to find the phantom boost issue... Looked at the plugs, they would look perfectly fine except for an amber-brownish tinge to the color... However, sure as shit- they were done...

Only problem is that I didn't make the complete association between octane booster & rice-mobiles until I was on my 3rd set of plugs less than a month later ($20 a plug gets expensive)... So yea, I do my best to make sure the noobs all know this about CA/SR/RB's. Also, that they don't have 87 octane gas in Japan (only 93,95 & 97 IIRC), so only use 93 octane or higher.

[Croustibat]

WOT at about 5000 rpm I reach a "wall" or something of the like. Or more like a bogging, actually. As I gradually let off the throttle I can feel the car sort of lunge forward as it tapers out of boost. My boost gauge reads only about 3-4 psi and the needle kind of flutters. Boost leak? Fouled plugs?

If it does have problem at WOT but not when going part throttle, it usually comes from a dead/dying fuel pump.

[So Make Like]

Check your WG actuator... cycle the rod open/closed manually. If it's stupid-easy to actuate, that's a great sign it needs to be replaced.

ALso, if you used any type of fuel system cleaner, octane booster etc- then it's your plugs. That stuff cooks SR/RB plugs. Also always run 91-93 or higher octane.

Come to think of it, I did use a fuel cleaner a couple months back and on top of that, I think my spark plug well gaskets might need replacing. I lightly burn oil, hence the smell and light smoke. I'll try replace the gaskets and change the plugs and get back to you on that.

If it does have problem at WOT but not when going part throttle, it usually comes from a dead/dying fuel pump.

Alright, I stand corrected. It doesn't only happen at WOT. Although, I just installed a new circuit sports fuel pump to check anyway. Nothing has changed.

[Mikester]

Hopefully it's your plugs. For future reference- Only 'safe' way to clean out our fuel systems is to drop the tank & empty/vacuum it out, replace the sock on the fuel filter, blow out all the hardlines; change the filter and send the injectors off for proper cleaning/servicing by places such as WitchHunter.

None of those 'snake oil' cleaners do our engines any justice ;)

[MADE]

If it does have problem at WOT but not when going part throttle, it usually comes from a dead/dying fuel pump.


Had the same problem chased everything else cause my FP was only 6 months old. Ended up being a bad pump. This is good advice.

[So Make Like]

May or may not be related, but to save from starting a new thread; why the hell does my boost gauge read a vacuum of 30 at idle? I hear 20 is about normal. I also die out sometimes when I clutch in after bringing the revs up above 3-4k. It's like the motor doesn't catch itself and return to idle properly. Not always.

[Mikester]

^^Bad plugs... Lack of sufficient back pressure... any number of things.

[ultimateirving]

May or may not be related, but to save from starting a new thread; why the hell does my boost gauge read a vacuum of 30 at idle? I hear 20 is about normal. I also die out sometimes when I clutch in after bringing the revs up above 3-4k. It's like the motor doesn't catch itself and return to idle properly. Not always.

Hey man check ur iacv. That is what catches the idle as RPMs drop. It also lets air in during idle. so perhaps it stuck shut or something

[So Make Like]

An update: I changed and gapped new bkr7e plugs to .30, changed/upgraded to a tt z32 fuel filter and changed out and re-secured new vac lines in more of an organized manner. Threw in my boost/vac gauge and agency power mbc while I was at it. It's set to flow all boost pressure through to the wastegate, so it doesn't really matter. Anyway, all of this and it still bogs with presence of a lingering scent of unburnt fuel. Not raw fuel, it's not leaking anywhere. Idles fine, revs fine without load, dies sometimes when clutching in, vac at idle is 28-29.

EDIT: I stand corrected. Even without load/in neutral, it bogs and sounds somewhat like a 2 step rev limiter at around 5k. It reeks of fuel and I can't even drive normal anymore. The bogging is consistent for as long as I'm on the throttle. My idle is a bit weird and unsettled now.