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Boost and Wastegate question?

8K views 27 replies 6 participants last post by  jackblack 
#1 ·
Ok first of all I searched through like 4 pages of threads before I gave up and just posted this.

I have a 07 subaru wrx with TBE & a Cobb AP short ram intake with a Stage 2 tune.

I've noticed my boost is not exactly hitting my target boost through 1st and 2nd gear, but its pretty close. Yet when I hit 3rd gear I don't even come close to the target boost. Can this be a cause of the wastegate arm needing to be adjusted or something else? I've read where a lot of people don't hit their target boost and thats why they adjust their wastegate arm, but couldn't really find anything where they were close to it in 1st and 2nd and then not the rest of the gears. Don't really want to go adjusting anything or changing anything until I know for sure.
 
#2 ·
Have you contacted Cobb directly about this. You can call or email. They are usually pretty good about getting back to people and are really friendly. I cant really offer experience or advice as I never had that issue when I was Stg2 on my AP.
 
#4 ·
I just realized I didn't fully explain what I have. I bought the cobb intake cause I was gonna get the cobb ap, but then I went with opensource and got the stage 2 tune from xpt. Ill try contacting them though and see if with their tune if sometimes you need to adjust the wastegate
 
#5 ·
By the standards of heat, load, and the way turbo's work. If you are tuned for 3rd wot which most cars are, you will probably not quite hit target boost in 1st or 2nd, because the turbo simply doesn't have enough load, heat, or time to spool. If it is getting close in 2nd and way off in 3rd it is highly unlikely it has anything to do with wastegate, is it spiking and over compensating? Is the target just way out of the turbo's efficiency range? What is the target boost?
 
#6 ·
I'm going to try to get some logs later this afternoon so i can give ya'll a better idea of whats going on, but like i went to the track yesterday and it did great off the line all the way through 2nd gear and then like as soon as i hit 3rd gear it just felt like i had no power. I ran a 9 flat on the 1/8 mile marker and then a 14.6 on the 1/4 mile. Also I've been looking around and noticed something kind of strange i bought this car with most of the mods already on it and i didn't catch it when i pulled the original tune off of the car until now, but its not the factory tune. A lot of the tune is extreme to the max but nowhere felt the same as the stage 2 tune i got from xpt so i guess thats why i thought it was just a factory tune. I'm going to try to attach the tune I pulled off of my car and let ya'll look at it and see what kind of tune this person was trying to do.
 
#11 ·
I haven't but I will. I was planning on replacing the y-pipe and coupler going to the intercooler cause they are the stock ones and look a little worned out so I guess its possible it could be leaking from there. Other than a possible boost leak does everything else look ok
 
#13 ·
his IAM looks good on the logs (1). I would be interested in looking at the comp table, not sure why on your run through the gears your wgdc's are hitting 67ish trying to compensate and on your 3rd gear wot run they sit at 59. I would think if it was a boost leak, which is still possible, your wgdc's would be hitting the table max trying to compensate. I don't see them doing that. Would like to see the +/- % adjustment in the comp. I won't have access to my tuner laptop till tonight, but I can't help but wonder why your wgdc's are not hitting 67 like they were in your from dead stop run, in which they were getting within 1 pound of target boost, which could be anything really, and yeah .5 - 1 lb could be caused by a wastegate spring getting a bit weaker "IF" the wgdc is hitting max duty in the table, it would open quicker and require a bit more wgdc numbers, still doesn't explain why it didn't compensate.
 
#15 ·
I didn't post his IAM in any of those logs. Also are you running any type of aftermarket boost controller? I.e. GM, Grimmspeed.
So confused, I see IAM (Multiplier) in all of them..? Scroll down, or we are looking at two different things. His IAM looks good, and the boost controller I wouldn't think would matter if his ecu isn't telling it to open/close, you could bump the comp a bit if it was a 3 port, but again, his ecu isn't trying to compensate; 7% can make a world of difference on a soft spring (Stock).
 
#18 ·
If it was getting a bit soft, you could give the actuator a turn or two and log. Although, I wasn't really suggesting that is the fix, although it could be a 'work around', I am more interested in knowing why the ecu didn't try harder to get you to where you needed to be. It's possible the +/- error % in the compensation table is whacked out.
 
#19 ·
As long as I know I can't get in trouble for doing it I will post the xpt stage 2 tune on here so you can look at their table and see maybe if it is in just the tune itself, but it'll have to be later tonight cause I don't have access to my laptop that has it on it right now
 
#20 ·
Ok here is the xpt stage 2 map. the ecu definition zip file is so that you can open it up to view it, but won't let anybody actually open it up to tune their car with it so it won't be like me giving away a tuned map that xpt makes money off of. To be perfectly honest comparing it to the tune that was originally on my car it has a better opening for acceleration but just dies out after 4500 rpm which could explain my loss of power when i get into 3rd gear at WOT just because by the time i get into 3rd gear i'm around 4500 rpm. So if that is the case any suggestions on what to adjust to fix that and how much of an adjustment i should make with the tune?
 

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#24 ·
Make adjustments on what? The bpv? Nah there's nothing under the hood that I can manually adjust other than the wastegate arm, but I have been reading where some people have had problems with their BCS going bad. Could this be a possible problem with mine or would show more of a drastic loss of boost then what im showing right now
 
#25 ·
If your boost controller was bad, you would be on pure wastegate spring pressure, which is probably around 7lbs. So highly doubtful it is your controller. If I was in your situation and I was getting as close as .5lbs from my target, I would guess that it's nothing major mechanical and probably in your tune. I would put a couple turns on the wastegate actuator and run a log, it's not going to hurt anything. I would not be looking for ghosts on such a small amount of boost, even 2lbs at 5k isn't really telling us much. I tried to open the tune but never got the defs to work properly, I am still a bit concerned with why the ecu didn't try harder, but as long as it's not totally whacked and is doing it's job to a certain extent I would adjust the actuator and see what happens. Go in baby steps and log each time, I would get where it's within .5lbs consistently in 3rd and then do a 4th gear pull to 3800 or so and make sure you aren't spiking.
 
#27 ·
WG spring pressure is 9lbs if i'm not mistaken. OH, mark and pay close attention how many times you turn it.

Check this out, buddy of mine has an 05 Baja and was having issues hitting >8lbs of boost and we thought it was the BCS.

Low and behold at the gas station he normally used switched the octane signs around (93 WAS on the right and is now on the left) and he has been running 87 for the past 2 fillups. Nonetheless, the plugs took a crap and currently is needing them done (still not getting past 10lbs)

Not that it matters on THIS particular issue, but could be relevant as I don't tune anyones' car let alone mine.
 
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