Odd boost behaviour

crembz
Impreza RS Driver
Posts: 179
Joined: Wed Mar 28, 2012 5:58 pm

Odd boost behaviour

Postby crembz » Sat Feb 18, 2017 4:29 pm

Hi there,

Got some strange behaviour on my gc8 where it seems to be bleeding boost or something.

So in 1st gear all seems good, boost feels strong to redline.

In 2nd, boost feels strong up to about 5500 rpm, then dips slightly then picks up again.

In 3rd I get boost until about 4500 rpm, then it feels like it bleeds boost completely. If I try and power through it, it will eventually pick up again at about 6000rpm. Climbing a hill in anything but 2nd is near impossible.

The symptoms get worse in 4th and 5th.

I'm not running a boost controller, stock air box 3" turbo back. The car has an SMT6 which I'm planning to swap out for a haltech. I'm not running a boost gauge so I can't see the drop, but it's very noticeable.

Restrictor pill is in place and I've checked the lines. No odd noise when this happens so haven't sprung a massive leak.

What could potentially cause such a symptom? I am thinking it's tube related.

ryano
Impreza RS Driver
Posts: 244
Joined: Thu Aug 19, 2010 9:12 pm

Re: Odd boost behaviour

Postby ryano » Sat Feb 18, 2017 4:42 pm

put a manual boost controller on it and a gauge, it will be the 3 inch and the factory boost control not getting along. also i have a haltech ps1000 with my99/00 loom for sale if your keen just need an air temp sensor

crembz
Impreza RS Driver
Posts: 179
Joined: Wed Mar 28, 2012 5:58 pm

Re: Odd boost behaviour

Postby crembz » Sat Feb 18, 2017 5:18 pm

Thanks I'm guessing it's something like that. It's as if the ECU sees the boost build, then freaks out and opens the wastegate. Would have thought that piggyback SMT6 would do the job.

I'm eyeballing an aem boost gauge, will eventually get a matching wideband and oil pressure. Is a manual boost controller necessary if the haltech is going in, thought the haltech boost control would be enough.

Yeah I saw your post re the haltech. Unfortunately I'd already paid a deposit on a new haltech. Got it at a decent price thankfully.

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ryano
Impreza RS Driver
Posts: 244
Joined: Thu Aug 19, 2010 9:12 pm

Re: Odd boost behaviour

Postby ryano » Sat Feb 18, 2017 7:57 pm

yes haltech does the job, i was taking about a fix for now, who is doing the tuning for you?

retroguy
Impreza WRX Driver
Posts: 335
Joined: Wed Mar 30, 2016 6:06 pm

Re: Odd boost behaviour

Postby retroguy » Sat Feb 18, 2017 8:29 pm

Ive got a v5/6 sti tmic with samco hose and intake air temp sensor tapped in with gauge.

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crembz
Impreza RS Driver
Posts: 179
Joined: Wed Mar 28, 2012 5:58 pm

Re: RE: Re: Odd boost behaviour

Postby crembz » Sat Feb 18, 2017 8:44 pm

ryano wrote:yes haltech does the job, i was taking about a fix for now, who is doing the tuning for you?

I'm getting it done at revzone in the next couple of weeks. Suppose I'll have to live with crappy boost until then. Probably should get that boost gauge in anyways.

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crembz
Impreza RS Driver
Posts: 179
Joined: Wed Mar 28, 2012 5:58 pm

Re: RE: Re: Odd boost behaviour

Postby crembz » Sat Feb 18, 2017 8:45 pm

retroguy wrote:Ive got a v5/6 sti tmic with samco hose and intake air temp sensor tapped in with gauge.

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I know you do ;) Probably gonna keep the stock tmic, save the cash for a fmic later on.

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retroguy
Impreza WRX Driver
Posts: 335
Joined: Wed Mar 30, 2016 6:06 pm

Re: Odd boost behaviour

Postby retroguy » Sat Feb 18, 2017 8:51 pm

All good.....

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crembz
Impreza RS Driver
Posts: 179
Joined: Wed Mar 28, 2012 5:58 pm

Re: Odd boost behaviour

Postby crembz » Fri Feb 24, 2017 7:12 pm

So turns out wastegate was stuffed. Fixed, now have the opposite issue, boost hitting 20+psi at wot. Lol

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