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Rb26 - Noob Question Regarding Boost

UNR33L

By UNR33L,
in Engines & Forced Induction

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UNR33L Grand Master

UNR33L

Posted
Posted

Hi guys,

Just a quick question I'm sure:

Basically I've owned my R33 GTR for about 2 months now, I put some apexi pods filters on it and just has a cat back exhaust at the moment otherwise completely stock.

Now my boost gauge use to say -11 ish on idle and boost up to abou 10 PSI, (on both my mechanical boost gauge and stock gauge), and now after a oil change (duno if it could be related at all) sits at about -2 ish on the gauges and only found that its boosting up to about 6-7 PSI? and car just seems a little slower in general..

Now I'm no engine guru but my first thought was maybe there is a leak somewhere in my FMIC piping? but figure I'd just ask here to see if this has happened to anyone else.. sorry if its been answered before but couldn't find anything.

Thanks in advanced,

Leigh

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Beer Baron Grand Master

Beer Baron

Posted
Posted

yep, most likely a pipe blown off, or vacuum hose off. best bit if you are not sure what to look for is take it to a mechanic and get them to find the missing/split/blown pipe. easy fix.

UNR33L Grand Master

UNR33L

Posted
  • Author
Posted

Ah ok no worries, it must be only small / hard to find if its still getting some boost I guess? I was going to get some parts and a tune by Status so I assume Trent should be able to find it if I cant haha

edit: is there any common places to look?

StealthX Veteran

StealthX

Posted
Posted
Ah ok no worries, it must be only small / hard to find if its still getting some boost I guess? I was going to get some parts and a tune by Status so I assume Trent should be able to find it if I cant haha

edit: is there any common places to look?

Does your car have a front mount?

If so, the turbo > first hot pipe, is a common one on aftermarket kits. So is throttle body and first of the cold pipes.

Are you blowing any black smoke and is it idling rough?

UNR33L Grand Master

UNR33L

Posted
  • Author
Posted

Its just got the stock front mount

I will check pipes when I have a chance

It doesn't seem like its blowing to much black smoke if any, the rear of my car gets a little black but seems fairly normal black-ness to be honest.

It seems to idle a little rough sometimes but not at all times, and also seems after I turn the car off for say 5 minutes (get petrol or what ever) get back in and drive off it has trouble when it hits boost seems to missfire a bit? or at least seems like that and also will idle rough at this stage as well.

UNR33L Grand Master

UNR33L

Posted
  • Author
Posted

Used a oil filter removal chain, and then replaced filter with a socket type filter 'Drift' brand.

The only thing I saw near the filter was something going to the front diff? a wire or something from memory

DVS JEZ Grand Master

DVS JEZ

Posted
Posted

under the inlet manifold there is a vineyard of black vacuum hoses. have a really good look, even use a mirror, its to coincidental that you changed the oil then this happened,

the reason i asked it you used a tool is this would make more sense if you pulled a hose off

Beer Baron Grand Master

Beer Baron

Posted
Posted

yeah trent will be able to find it no problem in 10 mins or so. he would have fixed literally hundreds of skylines with the exact problem you describe.

UNR33L Grand Master

UNR33L

Posted
  • Author
Posted

Yeah i'll try and have a look when i can.. if not fixed I'm sure Trent will have no problems he would be 100x better with this sort of thing then myself :down: I'm more of a I.T guru rather then engine troubleshooting..

And yes! GTR has FMIC! ;)

Happy that its nothing serious

GTRNUR Grand Master

GTRNUR

Posted
Posted

The map sensor for your gauge is located on the drivers side of the engine bay near your brake booster. There is a hose that goes from that to the back of the plenum near the firewall. The rubber tends to go hard, split/crack or just break off the brass pipe fitting that is on the back of the plenum.

You can easily reach it to check the hose. Give the hose a wiggle and squeese where it attached to the plenum. If its hard and cracked it will probably break off completely. Replacing the hose and doing a complete pressure test to identify other failing hoses is your best bet.

UNR33L Grand Master

UNR33L

Posted
  • Author
Posted

Well I feel like a idiot for not seeing this while changing the oil but here was the problem (simple boost gauge T-Piece rubber tube has busted):

Thanks for the help and advice people :ermm: gauge went from -2 ish to -20, and boosted 10psi plus now instead of dropping at like 6-7 psi and just not running well in general.

img0212q.jpg

:D

  • 4 weeks later...

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