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Old 06-08-2013, 09:22 PM   #1
IamGipper
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Default 02 WRX boost fluctuations

I posted a thread recently in the factory 2.0 engine thread about the problems I was having not being able to get past wastegate pressure. I cured the problem (restrictor pill was in the wrong spot), but now the boost fluctuates between 15 and 10 psi when I floor it. The car does have aftermarket headers, catless up pipe, and 3 inch tbe and it does not have a tune to support the mods yet. Are the fluctuation being caused by the mods messing with the stock map on the ECU? Will a tune get rid of the fluctuation? I had a local shop do a leak test on the induction system, they couldn't find any leaks. The CEL isn't on and no codes where thrown. All I need is a helping hand to point me in the right direction.
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Old 06-08-2013, 09:40 PM   #2
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It's very likely a tune will help, yes. Boost control duty cycle is likely out of whack for your current mods. Stock boost should be ~13.5 at initial spool, then a gradual taper down to ~9psi. I'm guessing you're seeing fluctuation from 15 - 10psi all under 5000 RPM. This tells you it's trying to control boost, but not succeeding very well.

If you haven't double checked for leaks through all the boost control hoses, then double check all that first, but it's likely a tune will clear up your issues.
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Old 06-08-2013, 09:49 PM   #3
Chaz2.5
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Check for leaks in the vacuum tubing and around the bpv. Also, did you mess with the wastegate arm at all? You may be overboosting and that is the ECU and BCS reacting. I was oscillating/fluctuating in 4th and 5th, just like you described, and by lengthening the wastegate arm by I believe it was 3 or 3 1/2 turns cured it.
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Old 06-08-2013, 09:50 PM   #4
IamGipper
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Thanks for the advice, mate. This car has been a long time coming, and all I want is for it to run right. I'm am fairly certain it does not have any leaks since the gauge reads 17 to 20inHG for vac when ever i'm off the gas. There are also no audible leak noises.
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Old 06-08-2013, 09:52 PM   #5
IamGipper
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Quote:
Originally Posted by Chaz2.5 View Post
Check for leaks in the vacuum tubing and around the bpv. Also, did you mess with the wastegate arm at all? You may be overboosting and that is the ECU and BCS reacting. I was oscillating/fluctuating in 4th and 5th, just like you described, and by lengthening the wastegate arm by I believe it was 3 or 3 1/2 turns cured it.
Which direction did you turn it?
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Old 06-08-2013, 10:17 PM   #6
IamGipper
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Quote:
Originally Posted by Chaz2.5 View Post
Check for leaks in the vacuum tubing and around the bpv. Also, did you mess with the wastegate arm at all? You may be overboosting and that is the ECU and BCS reacting. I was oscillating/fluctuating in 4th and 5th, just like you described, and by lengthening the wastegate arm by I believe it was 3 or 3 1/2 turns cured it.
It is doing it in all gears by the way, not just 4th and 5th
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Old 06-08-2013, 11:43 PM   #7
Chaz2.5
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I believe it was counterclockwise in order to make the arm longer. I was just noticing it in 4th and 5th
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Old 06-08-2013, 11:47 PM   #8
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Quote:
Originally Posted by IamGipper View Post
Thanks for the advice, mate. This car has been a long time coming, and all I want is for it to run right. I'm am fairly certain it does not have any leaks since the gauge reads 17 to 20inHG for vac when ever i'm off the gas. There are also no audible leak noises.
Boost leaks only present themselves when in boost. To be able to find leaks effectively, make a boost leak tester and do that. quick google should find many results on how to make a boost leak tester.
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Old 06-08-2013, 11:50 PM   #9
Chaz2.5
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You know, scratch everything and get tuned for that downpipe. You are overboosting in every gear and the oscillating is due to the bcs and ecu doing it's job. I missed the part where you said you did not have it tuned.
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Old 06-08-2013, 11:51 PM   #10
IamGipper
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That is what the shop used to test for leaks. I watched them do it. They pressurized the system up to 20 psi. They didn't find any leaks. This shop isn't your typical ricer shop that slaps a big turbo on your car and hopes for the best. All they do is Evo's and Impreza's.
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Old 06-09-2013, 12:02 AM   #11
IamGipper
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Quote:
Originally Posted by Chaz2.5 View Post
You know, scratch everything and get tuned for that downpipe. You are overboosting in every gear and the oscillating is due to the bcs and ecu doing it's job. I missed the part where you said you did not have it tuned.
Alright. I will update the thread once I have had the tune done to let you know if it worked.
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Old 06-09-2013, 12:04 AM   #12
Chaz2.5
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Honestly, if all the shop does is Evos and Imprezas, then they would know running an aftermarket 3" downpipe without proper tuning is a bad idea and can lead to issues, such as the one you are having now. I'm pretty confident a tune will fix the boosting issue
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Old 06-09-2013, 12:25 AM   #13
IamGipper
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Quote:
Originally Posted by Chaz2.5 View Post
Honestly, if all the shop does is Evos and Imprezas, then they would know running an aftermarket 3" downpipe without proper tuning is a bad idea and can lead to issues, such as the one you are having now. I'm pretty confident a tune will fix the boosting issue
They are one of those shops that won't tell you jack-**** about what's wrong with your car unless you are paying them $60 an hour to work on it. There was plenty of other things wrong with the car when I brought it to them to have it tuned the first time. They turned me away and said they wouldn't tune it until I fixed it. I paid them $153 just to do a leak check on the induction system, a smoke check on the exhaust, and pull engine codes. They pretty much showed me the codes they pulled and said "good luck".
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Old 06-09-2013, 01:25 AM   #14
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$60 an hour? That's cheap as hell. Avg shop time over here is 75-85/hr, with reputable performance shops being $20-30 more an hour.

Quote:
Originally Posted by Chase.5 View Post
Honestly, if all the shop does is Evos and Imprezas, then they would know running an aftermarket 3" downpipe without proper tuning is a bad idea and can lead to issues, such as the one you are having now. I'm pretty confident a tune will fix the boosting issue
You're pretty wrong.

02-03 wrx do not need tunes for downpipes.
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Old 06-09-2013, 01:45 AM   #15
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Either your mods or your vacuum tubes from the turbo to the EBC are the wrong size and your ECU is trying to compensate for the abnormality.

I took my car to PIA in WA and they came and swapped the hoses, told me to drive and test, and it worked, came back and paid for the hoses and i was off.
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Old 06-09-2013, 02:12 AM   #16
775WRX
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Its a tune. This seems to be "normal" for 02-03 wrx under WOT. I got a pro tune and replaced with grimmspeed ebcs and it stopped. Once the car is tuned it stops.
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Old 06-09-2013, 02:34 AM   #17
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Originally Posted by 775WRX View Post
Its a tune. This seems to be "normal" for 02-03 wrx under WOT. I got a pro tune and replaced with grimmspeed ebcs and it stopped. Once the car is tuned it stops.
Notmal....for you? Never had a problem with my car (with or without tune) and know several people with zero tune and zero problems
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Old 06-09-2013, 04:14 AM   #18
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thats why i put normal in quotes. Every one has different experience with cars. My car did it with a Intake and no tune then cobb stage 1 got rid of it then flashed to stock to sell the ap and it started again. Went pro tune for my TBE, intake, and GS ebcs and it stopped again. If this only occurs in WOT while in any gear then levels out in higher RPMs its the tune.
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Old 06-10-2013, 01:01 PM   #19
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Quote:
Originally Posted by IamGipper View Post
There was plenty of other things wrong with the car when I brought it to them to have it tuned the first time. They turned me away and said they wouldn't tune it until I fixed it.
I hate to break it to you, but that's the sign of a GOOD SHOP.

A bad shop just out for money will see there are problems and salivate. They'll tell you they can tune it, then they'll "find" the problems mid-tune. They'll tell you it's partially tuned so doesn't run right, and they NEED to fix the problems to be able to give you your car back. Then you're stuck... lucky if they only "find" the real problems and don't "find" something else.

Nothing in your description makes it sound like a bad shop.

So when they gave you the codes did you ask them what that meant and how much it would be to fix? They can smell a customer trying to pump them for enough info so they can fix it themselves, and of course will shut down those customers. I'm sure they don't mind if you fix it yourself if you know how, but a shop isn't going to give you step by step instructions.
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Old 06-12-2013, 06:06 PM   #20
IamGipper
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Quote:
Originally Posted by Concillian View Post
I hate to break it to you, but that's the sign of a GOOD SHOP.

A bad shop just out for money will see there are problems and salivate. They'll tell you they can tune it, then they'll "find" the problems mid-tune. They'll tell you it's partially tuned so doesn't run right, and they NEED to fix the problems to be able to give you your car back. Then you're stuck... lucky if they only "find" the real problems and don't "find" something else.

Nothing in your description makes it sound like a bad shop.

So when they gave you the codes did you ask them what that meant and how much it would be to fix? They can smell a customer trying to pump them for enough info so they can fix it themselves, and of course will shut down those customers. I'm sure they don't mind if you fix it yourself if you know how, but a shop isn't going to give you step by step instructions.
Sorry to bump an old thread. The guy who directly worked on my car while I was there brought me back to look at the car while it was still on the lift. He showed me what was wrong with it, and gave me a vague answer on where to start when fixing it. I realize that they were on my side when they told me they would not tune it and that they were saving me quite a bit of money and time by doing so. I will be having the car tuned on the 25th by the same shop, as I have fixed almost every problem they found. I hope it goes a bit smoother this time around.
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Old 11-06-2013, 01:27 PM   #21
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sorry to revive this thread but i am having the same problem. i just installed a catless dp, and i was tuned on stage 1 via cobb AP. i tuned the car to stage 2 last night and this morning on the way to work, the boost kept fluctuating. i contacted my mechanic and he suggested replacing the stock boost controller with the grimspeed ebc. but i read ill need to have it tuned. could it be tuned with the cobb ap or would i need to take my car to a shop? i am really not feeling putting my car on the dyno. please advise. thanks.
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Old 11-06-2013, 01:39 PM   #22
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Quote:
Originally Posted by Daddy_Digital View Post
sorry to revive this thread but i am having the same problem. i just installed a catless dp, and i was tuned on stage 1 via cobb AP. i tuned the car to stage 2 last night and this morning on the way to work, the boost kept fluctuating. i contacted my mechanic and he suggested replacing the stock boost controller with the grimspeed ebc. but i read ill need to have it tuned. could it be tuned with the cobb ap or would i need to take my car to a shop? i am really not feeling putting my car on the dyno. please advise. thanks.
You must have a custom tune made for any aftermarket bcs
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