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Old 08-01-2011, 10:25 PM   #1
MikeyAE86
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Default EJ20G target boost 12.8 only hitting 10. Problem?

Here is my problem:

On my 99% stock EJ20G ( K&N drop in, 05 sti DP)

im only hitting 10 psi at WOT.

So i thought it might have been the factory boost control. I can hear it clicking when i rev the motor up. And if i unplug it it only hits spring pressure ( 7 PSI on stock TD05H)

So then i thought maybe the ECU was screwed up somehow or mixed up with a wagon 10 psi ecu. So i just recived a Z4 ecu (12.6 target boost) and it too only hits 10 PSI

Now im stumped.


Any ideas?


Thanks in advance

-mikey b
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Old 08-01-2011, 10:44 PM   #2
69subaru360
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You added a second cat to the downpipe. Could be the restriction.

Clean the boost control solenoid, plug in the green connnectors under the dash so it clicks and spray brake cleaner through it. Be sure all the hoses are in good shape, properly routed and the restrictor is in place.

Or just put on a mbc and be done with it like everyone else does. You can turn it up to 14-15 psi then.
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Old 08-01-2011, 10:50 PM   #3
MikeyAE86
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yeah i just pulled the line off the wastegate and it pulls to 15 easy, i lifted at around 5k right as it touched 15 and my warning light went off

so gotta be the boost control


so just clean it up and try again?
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Old 08-01-2011, 10:50 PM   #4
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and the downpipe only has the primary cat, the second cat is gutted and missing
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Old 08-01-2011, 10:53 PM   #5
69subaru360
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Quote:
Originally Posted by MikeyAE86 View Post
so gotta be the boost control

Yes, try cleaning it. Really just pick up a mbc, set it and forget it. The boost control on these sucks anyway.
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Old 08-01-2011, 10:57 PM   #6
MikeyAE86
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ive got one. So 14 is safe? Im on 91 in CA and ambient temps of 100 degrees
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Old 08-01-2011, 11:06 PM   #7
69subaru360
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The fuel cut is 15.5 or so.

If you are worried about set it to stock boost levels.

The Z4 is a tame ecu compared to most of the other jdm ecus. You'd probably be ok.
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Old 08-02-2011, 12:24 AM   #8
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im going full noob here, but does anyone have a comprehensive vacuum routing diagram?
i recieved an engine in shambles
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Old 08-06-2011, 12:19 AM   #9
blkgm8
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Hey Mikey... Something is definitely going on with your boost control solenoid. My car NEVER saw below 12 psi with that ecu. I actually would go to 14 or so and then taper down a couple of psi. It could actually also be bad gas OR knock sensor because these ecu's are very smart and will pull timing and lower boost if you are knocking badly.

This is directly from Enduring Solutions website in the UK regarding the OEM JECS ecu:

"Closed Loop Knock Control is arguably the most important feature on a road car ECU. Given the variability of pump fuel in the UK, the amount of detonation an engine will experience on different tanks can vary considerably. An ECU equipped with knock control will listen to the output of the knock sensor and retard ignition timing until no more detonation is sensed. The OEM JECS ECU will also richen the mixture and reduce boost pressure if significant detonation is heard. An aftermarket ECU without this facility relies on every tank of fuel being exactly the same as the one it was mapped on or has to be mapped with a safety margin, costing power. Owners of knocklinks will know that activity between tanks of the same type of fuel can vary significantly, which is why knock control is one of the most important features of an ECU. It is very rare for aftermarket ECUs to offer it, even as a cost option. "

Enduring Solutions offers a tuneable daughterboard and software combo which turns our ecu's basically into standalones while keeping all the factory safety features of the ecu intact.

http://www.enduringsolutions.com/faqs.html

Last edited by blkgm8; 08-06-2011 at 12:33 AM.
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Old 08-07-2011, 11:11 AM   #10
TommyAtomic
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Rather roundabout way to say it sounds like a knock issue.

Quote:
Originally Posted by blkgm8 View Post
Hey Mikey... Something is definitely going on with your boost control solenoid. My car NEVER saw below 12 psi with that ecu. I actually would go to 14 or so and then taper down a couple of psi. It could actually also be bad gas OR knock sensor because these ecu's are very smart and will pull timing and lower boost if you are knocking badly.

This is directly from Enduring Solutions website in the UK regarding the OEM JECS ecu:

"Closed Loop Knock Control is arguably the most important feature on a road car ECU. Given the variability of pump fuel in the UK, the amount of detonation an engine will experience on different tanks can vary considerably. An ECU equipped with knock control will listen to the output of the knock sensor and retard ignition timing until no more detonation is sensed. The OEM JECS ECU will also richen the mixture and reduce boost pressure if significant detonation is heard. An aftermarket ECU without this facility relies on every tank of fuel being exactly the same as the one it was mapped on or has to be mapped with a safety margin, costing power. Owners of knocklinks will know that activity between tanks of the same type of fuel can vary significantly, which is why knock control is one of the most important features of an ECU. It is very rare for aftermarket ECUs to offer it, even as a cost option. "

Enduring Solutions offers a tuneable daughterboard and software combo which turns our ecu's basically into standalones while keeping all the factory safety features of the ecu intact.

http://www.enduringsolutions.com/faqs.html
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Old 08-07-2011, 05:46 PM   #11
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without the mbc my z4 would run between 10 and 13 psi depending on temp
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Old 08-08-2011, 02:14 AM   #12
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Quote:
Originally Posted by TommyAtomic View Post
Rather roundabout way to say it sounds like a knock issue.
Yea... I guess I could have just said it sounds like a knock issue without giving the reasons why to back it up. LOL.

Actually I meant literally when I said had that ecu in my car. He just picked it up from me. I just thought I would chime in with some information that may actually help with his problem.
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Old 08-15-2011, 10:59 PM   #13
klys
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Default I also need it

Quote:
Originally Posted by eg33GC View Post
im going full noob here, but does anyone have a comprehensive vacuum routing diagram?
i recieved an engine in shambles
Indeed I've been looking all over the net for a real MY92-95 wrx boost/vacuum line diagram.

I can't seem to reach more than .5bar the car feels sluggish

I have a new uncracked sti uppipe

pretty much a 3" turbo back

no known leaks

thanks to anyone who can help out

Also compression of all 4 cyl is between 170 and 173 PSI
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Old 08-16-2011, 02:52 AM   #14
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This is the best I have. It is for a '92 libertyRS EJ20G. It is close to the WRX. One difference that I know of for the vacuum side of things is that there are no purge valves on the JDM WRX.

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Old 08-16-2011, 07:29 AM   #15
luka
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libertyRS had a water-to-air intercooler?
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Old 08-16-2011, 12:17 PM   #16
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Yes.

Mikey what is your boost gauge reading when the engine is off? Is it exactly 0 or a bit below? That could also explain why you think you're only running 10 whil ein fact you might be running almost 13 above atmospheric pressure.
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Old 08-16-2011, 12:18 PM   #17
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indeed it did.

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Old 08-17-2011, 12:03 AM   #18
klys
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Quote:
Originally Posted by rob View Post
This is the best I have. It is for a '92 libertyRS EJ20G. It is close to the WRX. One difference that I know of for the vacuum side of things is that there are no purge valves on the JDM WRX.

thanks and which ports is which on the 3 port solenoid shown here:
I'm guessing if you turn the drawing 90 counter clock wise it should be OK?


Oh and is there really an O2 sensor cause I have the original dump pipe and it looks like a temps sensor...


I now have a brand new greddy downpipe without any holes except for a wideband around where the 2nd cat used to be.

thanks.
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Old 08-17-2011, 12:05 AM   #19
klys
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Source of some info concerning boost solenoid

http://autospeed.com/cms/title_Shoot...7/article.html
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Old 08-17-2011, 06:43 PM   #20
TommyAtomic
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Quote:
Originally Posted by klys View Post
Source of some info concerning boost solenoid

http://autospeed.com/cms/title_Shoot...7/article.html
That site seems to have alot of good info on pre-2002 wrx's in general including some great stuff on the differient subaru top mount intercoolers.
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Old 08-18-2011, 08:41 AM   #21
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Quote:
Originally Posted by klys View Post
Oh and is there really an O2 sensor cause I have the original dump pipe and it looks like a temps sensor...
On some JDM engines the O2-sensor is installed in the RH exhaust manifold right before the uppipe. In the downpipe there is an EGT-sensor.
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Old 08-18-2011, 11:18 AM   #22
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I am having the exact same issue with my 95 WRX STi.

Hitting 10 PSI consistently through every gear. Reset the ecu. All is fantastic. Car runs smooth and pulls very hard, but will not hit its "target" boost. I have been told the stock PSI on these cars is approx. 14 with the ecu in the V2 STi's.

I unplugged the line going to the wastegate as well. Boom 15 PSI with ease.

Does this mean there is something wrong with the factory boost solenoid? This has been asked but no one has given a straight up answer. Solution: Grab a MBC, set it and forget it at 15 PSI since the factory boost solenoid is clearly on its way out/not working correctly?
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Old 08-18-2011, 02:54 PM   #23
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By unplugging the line going to the wastegate, you theoretically get infinite boost right?
It is possible that your wastegate actuator is opening too soon but I would tend to say boost controller more (the wastegates rarely fail right?). And even if your wastegate is opening too soon, if you put in the MBC, the wastegate won't see any pressure until the MBC hits its point (unless it's one of those bypass ones).
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Old 08-18-2011, 10:20 PM   #24
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Quote:
Originally Posted by Marnix View Post
On some JDM engines the O2-sensor is installed in the RH exhaust manifold right before the uppipe. In the downpipe there is an EGT-sensor.
Yeah I looked under the car today and it's indeed there!

I did a boost leak test and I found that the gasket between my plastic turbo outlet pipe to intercooler was squeezed wrong.

I fixed it and now I'm getting close to .7 .8 kg/cm2 but car is still VERY slugish much like my 2000 Brighton when the check engine light is on due to a sporadic knock sensor fault (happens when it rains hard).

seems like the timing is being pulled.

can an ABS light put the ECU in limp mode as mine is on?

Last edited by klys; 08-18-2011 at 11:17 PM.
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Old 08-19-2011, 01:33 AM   #25
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Is the speedo working?
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