Low boost for no reason - Page 2 - Subaru WRX Forum
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#16 Old 09-20-2013, 10:26 PM
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No CEL,no codes. My brother hooked it up to his tablet last weekend to confirm that there was a problem. Boost was at 7lbs psi and my 0 to 60 was in the 8sec. range. Normally the max boost is between 13.5 and 14.1lbs psi and my 0 to 60 was between 5.6 and 6.1 sec. He also checked for codes and found none. We double checked that his tablet was working properly on his Mazdaspeed 3 and it checked out fine.

I wonder if I got into some bad gas?

All right, where is the distributor cap? I need to find the #1 plug wire to hook up my SUN machine.
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#17 Old 09-21-2013, 08:27 AM
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Quote:
Originally Posted by Fidrat View Post
I wonder if I got into some bad gas?
Good diagnostics, but I don't think low boost would be a result of fuel quality. Where are you buying your fuel from?

The handling of fuel at the retail gas station is the weakest link in the entire distribution chain, so I'd select gas stations that are concerned about quality.

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#18 Old 09-21-2013, 07:23 PM
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My subaru tech told me to only buy from shell and shevron, and never to pump while the truck is filling up the gas stations tanks.
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#19 Old 10-10-2013, 06:33 PM
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Well,I'm back to square one. The boost fell right back to where it was. What the hell is going on with my car?!

All right, where is the distributor cap? I need to find the #1 plug wire to hook up my SUN machine.
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#20 Old 10-11-2013, 09:37 AM
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Boost leak test.

Paul
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#21 Old 10-11-2013, 06:44 PM
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It can't hurt, but he said that the boost came back after a ECU reset, then cut out again. Could be a coincidence, but I'd lean more towards your EBCS.
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#22 Old 10-11-2013, 07:19 PM
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It's really weird, the boost comes on normally until it hits .04MPa. Then it's like hitting a brick wall. It stops dead on at .04MPa and won't go any higher!

I'd like to do a boost leak test but my local subie mechs only experience with a turbo is mine.(that means none) most of his work is on foresters and outbacks and the like. So if I want to take it to a dealership,that means a road trip and lots of cash. Something I'd like to avoid.

Is there a way to test the EBCS? Could it have something to do with the wastegate?

If it is the turbo,can they be repaired without replacing it? I just hit 98000mi and I'm trying to save up for a timing belt change.

All right, where is the distributor cap? I need to find the #1 plug wire to hook up my SUN machine.
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#23 Old 10-11-2013, 08:42 PM
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Disconnect the neg batt terminal

Take the BCS out and spray it with MAF cleaner or electronics cleaner....plug it back in

run the diagnostic test from connecting the green connectors

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#24 Old 10-11-2013, 08:52 PM
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Quote:
Originally Posted by pzr2874 View Post

run the diagnostic test from connecting the green connectors
Can you explain this more.It's a little over my head.

All right, where is the distributor cap? I need to find the #1 plug wire to hook up my SUN machine.
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#25 Old 10-11-2013, 10:55 PM
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Quote:
Originally Posted by Fidrat View Post
It's really weird, the boost comes on normally until it hits .04MPa. Then it's like hitting a brick wall. It stops dead on at .04MPa and won't go any higher!

I'd like to do a boost leak test but my local subie mechs only experience with a turbo is mine.(that means none) most of his work is on foresters and outbacks and the like. So if I want to take it to a dealership,that means a road trip and lots of cash. Something I'd like to avoid.

Is there a way to test the EBCS? Could it have something to do with the wastegate?

If it is the turbo,can they be repaired without replacing it? I just hit 98000mi and I'm trying to save up for a timing belt change.


If you have the stock TD04 turbo, it can be rebuilt, but its a lot cheaper to buy another used one, and rebuilds are a PIA. The 02-07 all had the same TD04's, and they can be bought on NASIOC for 125-150 in good condition.

But turbo's don't go out like this, normally they will eat oil and blow blueish smoke out of your tailpipe (failed oil seals), or they will make a horrendous screeching noise when you start to go into boost (Blade or shaft damage). What you are experiencing sounds like a typical boost leak (only hitting a little bit of boost) until you mentioned that it came back for a bit after you reset the ECU. This leads me to believe it is on the electrical side rather than mechanical. The EBCS is the way for your ECU to control boost. Sounds like its malfunctioning. You can try to clean it, if that doesn't work then you should try buying a new EBCS, they aren't that expensive, should be under 100 bucks.

To be safe I'd clean it and get a boost leak test if that doesn't work, just in case, its always better to start with the cheaper options. If you have a performance shop around you they should be able to do it, or try searching craigslist, someone might do them from their garage. If you have a buddy with a air compressor, you can borrow it and make your own leak tester for around 5 bucks from things you can get at home depot or lowes, heres a how to:

How To: Boost leak tester for $5.02 - evolutionm.net
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#26 Old 10-13-2013, 01:57 AM
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Well, I removed the EBCS,tested it,cleaned it,put it back on. It tested ok. I also cleaned the MAF and air filter and reset the ECU. Then I hooked it up to my brothers tablet and I saw no improvement,no codes.This time boost did NOT come back. Max boost was 8 PSI with a 0-60 in the 9sec range. This is unacceptable! Looks like I'm gonna' have to plan a road trip to the dealer.!Cry!

All right, where is the distributor cap? I need to find the #1 plug wire to hook up my SUN machine.
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#27 Old 10-13-2013, 06:05 AM
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Your ECU is running in limp mode or wastegate only pressure for some reason. Have you checked the vacuum lines running to the turbo from the wastegate? Also pull the heat shield off and see that the wastegate arm is moving correctly. When was the last time you changed plugs and your fuel filter?

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#28 Old 10-13-2013, 10:35 AM
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Your ECU is running in limp mode or wastegate only pressure for some reason. Have you checked the vacuum lines running to the turbo from the wastegate? Also pull the heat shield off and see that the wastegate arm is moving correctly. When was the last time you changed plugs and your fuel filter?
Plugs at 60,000mi on the tick. Fuel filter about 5,000mi ago. I'm at 98,000 now. This car is VERY WELL taken care of.

I will look at the wastegate today. What should I be looking for? what does "moving correctly" look like?

All right, where is the distributor cap? I need to find the #1 plug wire to hook up my SUN machine.
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#29 Old 10-13-2013, 07:44 PM
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Pull the C clip holding the wastegate arm to the flapper. Move the flapper arm around and see if it has issues moving, it might be getting rusty with all the heating and cooling cycles it goes through. You should be able to move the wastegate arm back and forth with a bit of effort. So when you reset the ECU it ran fine then how long before it started low boost again?
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#30 Old 10-13-2013, 10:08 PM
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Pull the C clip holding the wastegate arm to the flapper. Move the flapper arm around and see if it has issues moving, it might be getting rusty with all the heating and cooling cycles it goes through. You should be able to move the wastegate arm back and forth with a bit of effort. So when you reset the ECU it ran fine then how long before it started low boost again?
Ok I'll do that. It ran OK for 100mi or so.

All right, where is the distributor cap? I need to find the #1 plug wire to hook up my SUN machine.
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