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Old 01-29-2015, 03:43 PM   #1
Loomis112
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SR Sr20det overboosting still

So I have had a problem for the last few weeks where my car builds the right amount of boost (10 psi) then after a certain rpm it overboosts to about 16 then spits at me.

So far I have checked my maf, changed and gapped spark plugs correctly, set timing, bought a brand new intercooler and piping installed it and checked for boost leaks anywhere and nada, I have even disconnected the waste gate arm so the flap was always open it should only stay around 2-3 psi right? WRONG it goes about 2-3 until 4k then it just builds and builds until 16 then bam spits at me.


I've tried everything I was for sure it was a boost leak but now I am just out of ideas and struggling
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Old 01-29-2015, 04:22 PM   #2
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spits at you? wtf is it spitting???
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it'll fit JANK.. and no one likes Jank except Broke ass zilvians.
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Old 01-29-2015, 04:39 PM   #3
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dope ass rhymes.

I mean it cuts out, whatever you want to call it
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Old 01-29-2015, 04:45 PM   #4
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You have to provide a detailed description of your setup with pictures and probably video. Your first issue is you can't say that your boost, reaches the correct amount 10psi then over boost to about 16psi based on rpm. You set boost at full throttle then verify throughout the gears and rpm range. I use 4th gear, with an ebc you might make adjustments for boost to come on earlier or not over boost and or set a safety margin for when you do.

Waste gate upgrade, port flapper or go external.

And setup information would also elaborate, as to why you cant boost 16psi without spitting? breaking up? Brap brap brap? Or over fueling? More info! Video!

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Old 01-29-2015, 04:57 PM   #5
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Ill try to get a video soon enough but for now ill just say what I have.

Gt2871, 550cc injectors, z32 maf, apexi neo afc, aem truboost, etc.

Latley to test things out ive been running the boost controller off so it just goes by the stock wastegate

And its more of a breaking up at 16psi, im trying to maintain 10psi but its just keeps building after the certain rpm no matter what gear
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Old 01-29-2015, 10:08 PM   #6
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SR

https://www.youtube.com/watch?v=DDbIxv_O1lo


So here it is 4th gear pull,waste gate wide open the whole time
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Old 01-29-2015, 10:31 PM   #7
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That thing is getting mad lean. My car used to do that shit in the cold. Anything under 57-58 degrees and it did that.
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Old 01-30-2015, 07:31 PM   #8
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Its weird that it just started doing this not too long ago+ what could've happened??
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Old 01-30-2015, 09:00 PM   #9
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Plug gap? Do you have any sort of tune or are you trusting your motor to that archaic POS SAFC? What you're experiencing is called boost creep and most likely your 2871r Wastegate is rated for 1bar or 14.7psi.

Is that a wideband or a narrowband gauge on your pillar? Have you recalibrated it if it's a wideband?
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Old 01-31-2015, 03:09 AM   #10
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Yeah that gauge I assume is the truboost?
And jr_ss is right about the gate, but it should be tied open when you disconnect the arm from the flapper, to rule out sticking. The safc would have to be configured correctly, and then tuned correctly for it to half way work. And that could be why you're breaking up at only 16psi. The injectors alone should be able to support the boost, but with the safc tune, can't say for sure. The most common injector size for the 2871r are 740's.

You can try swapping internal waste gates, tune your setup for 1bar and or get rid of the safc and get a ROM tune.

Try setting the boost for 1bar.
Do you have a wideband? You need it, if you don't.

Is the actuator arm adjustable, if so make the rod longer to lower boost.

The truboost isn't setup correctly either, there should have been a warning or action taken when you went above 11psi.
The over boost warning and protection feature. So basically every time you hit boost, your gauge would show warning and or the solenoid would be turned off.
Because
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my car builds the right amount of boost (10 psi) then after a certain rpm it overboosts to about 16 then spits at me

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Old 01-31-2015, 09:34 AM   #11
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I have a video of ot happening on my other post
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Old 01-31-2015, 09:35 AM   #12
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With the wastegate stuck open
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Old 01-31-2015, 10:02 AM   #13
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You have multiple issues with your setup.
The boost issue seems to be most important to you, right? So is your exhaust, free flowing 3in no cat etc?
If not, then maybe there's to much back pressure, or restriction to allow the exhaust to flow through the waste gate port hole even when flapper held open.

Free/inexpensive things you can try:
Unbolt part of your exhaust. (Catback) install a stock or adjustable waste gate arm. Set the boost for 1bar (14.5psi).

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Old 01-31-2015, 05:58 PM   #14
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Its a 3 inch straightpipe
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Old 02-01-2015, 12:05 PM   #15
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first, bin that crappy SAFC and get a tune . Then enjoy your sr20 at 16psi, or more.

Why you installed a gt2871r to run it at 10psi is beyond me, the stock T28 can do that while spooling faster
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Old 02-01-2015, 12:40 PM   #16
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first, bin that crappy SAFC and get a tune . Then enjoy your sr20 at 16psi, or more.

Why you installed a gt2871r to run it at 10psi is beyond me, the stock T28 can do that while spooling faster
lol, this put a smile on my face!
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Old 04-10-2019, 09:39 PM   #17
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Hey guys I’m over boosting like a mother trucker

I’ve never hit pavement with it yet

Just got it running, and live on gravel

Scared ima blow it up

Manual boost controller, never adjusted it

Fouling plugs very fast,

Only 550ccs inj

T28

A’PEXi air filter

I’m thinking the wastegate is froz

Need help
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Old 04-11-2019, 08:25 AM   #18
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step 1: ditch the manual boost controller.
step 2: check if the wastegate actuator will hold vacuum
step 3: if you're fouling plugs, what is the ecu tuned for??? do you even have a modified ecu or standalone? reflash ecu? we need more info if we are to help you diagnose your situation
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