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Discussion Starter · #1 ·
I just installed a grimmspeed catted downpipe and turbo xs uppipe on my wrx and now im having issues with overboosting, im hitting about 22psi (reading on accessport) on the ots stage 2 tune. i had the car stage 1 tuned for a couple months and it was not having any issues, boosted to about 13.5psi then tapered off. I re-checked everything and made sure everything i put in is tight. right now i dont have an o2 sensor in the exhaust (about to install one) could that be causing overboost?
 

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Discussion Starter · #2 ·
forgot to add it doesnt hit fuel cut or trigger any cel's im just reading over 20 psi when i get on it with the accessport then i let off.
 

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Discussion Starter · #4 ·
I don't really want to do a full pull while it's overboosting, when I see it go to 20psi I let off.
 

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If you mean the main front O2 sensor yeah put that in before you do anything else including more driving hard at all.
 

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cole0502 said:
I don't really want to do a full pull while it's overboosting, when I see it go to 20psi I let off.
How can we tell you what's wrong if you don't give us the data to interpret?

With no data to look at, I'd guess a BCS line malfunction.
 

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Datalog instead of making excuses

Sent from my SHIELD Tablet K1 using Tapatalk
 

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Discussion Starter · #8 ·
I mean the rear o2 sensor on the downpipe not the one on the manifold. I haven't been driving it hard at all, i don't think it's a good idea to do a full wot pull to get a datalog when I know there is an issue.
 

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Discussion Starter · #9 ·
I checked all the lines that go to the bcs, intercooler and throttle body hoses, and all the bolts on the uppipe and downpipe, is there any where else that could be leaking boost? could going stage 2 just have put too much stress on the old bcs?
 

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I checked all the lines that go to the bcs, intercooler and throttle body hoses, and all the bolts on the uppipe and downpipe, is there any where else that could be leaking boost? could going stage 2 just have put too much stress on the old bcs?
First it is not the rear o2 which you don't really need. Nor the front o2 for that matter - that one is important for other reasons though.

Second it can't be your BCS unless it is stuck open. When they fail they usually don't open, which reduces boost. Even if it were stuck open I don't think you'd get runaway boost at all.

Are you getting runaway boost (you hit 22 and saw it and let off) or did it just peak at 22? If you did you have a leak in a BCS vacuum line, no restrictor pill, or your wastegate actuator should be checked. Is it springy and pretty damn hard to pull open?

If not, load the LWG map and do the log. Your car will pull timing to protect itself if needed. Be sure you read up and get the parameters for boost control without too much other stuff other than the standard knock control, IAM, RPM, TP, load stuff.
 

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Discussion Starter · #12 ·
Ok thanks I'm gonna check all that and put the o2 sensor in tomorrow, if I don't see anything wrong I'll try out the low wastegate map.
 

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Discussion Starter · #13 ·
I put the o2 sensor in and tried the low wastegate map and exact same thing happened. i pulled on the wastegate arm and it does seem a bit too tight but i dont know how it should feel. I have a datalog of it but how do i upload it? i use google drive to view them and it says it is invalid when i try to upload it. But it peaks at a bit over 22 and goes down to about 19 by 6k. There's no knock and afr is at 0 through the pull, but my aft learning is at about +4 when cruising.
 

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Discussion Starter · #14 ·
my wastegate duty only peaks at 50% at 3600rpm then goes back down to 0% by 4k. It starts going over 16 psi at 3600 rpm so im guessing it is a wastegate issue?
 

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I'm not sure, maybe try google again. You should be able to upload the excel file fine and set it to public. Otherwise you will have to use another file host.

Did you happen to log the boost error as well? If not you really need to look at that.

The wastegate is supposed to be fairly tight.
 
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