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Old 08-05-2007, 03:55 PM   #1
amazonparrot
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Exclamation Vishnu Stg. II Boost Oscillation *HELP*

Before I go into the problem I suppose it would be wise to post up the info on the car:
2003 WRX
Vishnu Stage II (v350) which includes:
3" Vishnu Signature exhaust
Vishnu (Helix?) Divorced Wastegate Downpipe
Vishnu Flex Up-pipe
IHI V-34
STi Pinks
Walbro FP
Stock Intake Tract (Have Run and tested it both With a K&N Filter and W/o)
ECUtek Reflash
Stock steering column mount boost gauge

Ok, thats all I can remember right now as far as the relavent drivetrain information goes.

The Problem:
Boost climbs to around 18-18.5 psi, and then wavers back to around 13-14 and then back up to 18 and so on and so forth all the way to redline, leading to obviously huge surges in power that frankly...suck. I bought the car about 4 weeks ago, and had taken out the intake resonator and put the K&N filter in the car, which was when i first started NOTICING the problem (I figured I just made the ecu map unhappy with a different air flow reading) so I reset everything back to the way I got it (stock intake resonator and paper filter) and while the problem was less pronounced, it is definetly still there. I have since Unplugged the battery and reset the ECU on multiple occasions, and nothing has changed. I also took a quick look over the vaccuum lines and anything obvious, but came up empty handed... Pretty much everything seems in perfect condition as the car only has 25k on it and is amazing. Anyone have a suggestion of what could be causing me this problem and what I could do about it? (and for the record, I spent plenty of time searching)

Thanks Guys!
-Andrew R.
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Old 08-05-2007, 05:12 PM   #2
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it seems like its overboosting, and the turbo dynamics is trying to keep the boost down where it should be. You may need a re-tune.
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Old 08-05-2007, 06:21 PM   #3
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alright, as soon as I can get vishnu to give me a call back on the phone, then I will ask them about that, in the meantime, is there any chance that it could be something like the boost control solenoid going bad?
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Old 08-05-2007, 08:39 PM   #4
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anyone else? please?
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Old 08-05-2007, 11:46 PM   #5
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take it easy on the car until get it resolved would be the best advice to you.
good luck
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Old 08-06-2007, 11:32 AM   #6
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is it possible that the map was erased during the unplugging of the battery? B/c you are supposed to be able to switch between hi boost and low boost modes, and when i try, I notice NO difference, so maybe the map is gone??
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Old 08-06-2007, 10:37 PM   #7
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no it doesn't work that way
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Old 08-07-2007, 02:11 PM   #8
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Thanks for everyones input so far. Does anyone have a suggestion i can acutally check something for??? I would really like to have this resolved
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Old 08-08-2007, 01:30 PM   #9
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You probably need to lower the max wastegate values a little. Also, you may want to clean the MAF sensor.
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Old 08-08-2007, 02:23 PM   #10
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are you getting a CEL?
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Old 08-10-2007, 06:55 PM   #11
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Can you post a log?
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Old 08-11-2007, 11:56 AM   #12
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I will give the MAF cleaning a try.
There is a code 546 (EGT over temp) but that is probably unrelated b/c it was a pre-existing condition.
As far as posting a log, do you mean a datalog such as with a program like delta dash? Because i dont have any logging tools at all...
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Old 08-11-2007, 12:34 PM   #13
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no, enginuity and a tactrix cable for logging. the program is free
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Old 08-13-2007, 12:15 PM   #14
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If you have the Vishnu tune, it's probably an ECUTek tune.
Depending on when it was flashed you may or may not be able to get in and modify it.
however, if it IS in fact the vishnu ecutek flash, the maps aren't all used the same and it can be confusing to adjust. Especially if you have the different map feature on your flash.

When you removed the resonator it is possible that you lowered the pressure ratio across the turbo. This results in lower WGDCs being needed to control boost as well as slightly different turbo dynamics. The tuner obviously didn't have this in mind (not his fault). Sounds like you need a retune to properly compensate for what you have done to the car. If you just want the boost fixed, it shouldn't be too difficult or take too much time.
I see that you are in Virginia. Maybe you can get ahold of Dyno Inc or All Aspects in the HR area. They have a few tuners there that can help you out.
I have some buddies in the area that may be able to lend you a hand as well.

-Dominic
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Old 08-13-2007, 06:49 PM   #15
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Quote:
Originally Posted by KitoAutoSport View Post
If you have the Vishnu tune, it's probably an ECUTek tune.
Depending on when it was flashed you may or may not be able to get in and modify it.
however, if it IS in fact the vishnu ecutek flash, the maps aren't all used the same and it can be confusing to adjust. Especially if you have the different map feature on your flash.

When you removed the resonator it is possible that you lowered the pressure ratio across the turbo. This results in lower WGDCs being needed to control boost as well as slightly different turbo dynamics. The tuner obviously didn't have this in mind (not his fault). Sounds like you need a retune to properly compensate for what you have done to the car. If you just want the boost fixed, it shouldn't be too difficult or take too much time.
I see that you are in Virginia. Maybe you can get ahold of Dyno Inc or All Aspects in the HR area. They have a few tuners there that can help you out.
I have some buddies in the area that may be able to lend you a hand as well.

-Dominic
Thanks Dominic, you are a lifesaver. Yes is it def. a ECUtek retune by Vishnu (ecu mailed out to them, flashed and mailed back by previous owner). Why wouldnt this problem resolve itself (map-wise) when I re-installed the resonator and unplugged the battery to undo any learned characteristics? for now I would like to just have it set back to the way it was, and eventually have a full re-tune done with a FMIC and intake etc etc.

On another update, as I continue to drive and make note of more characteristics, I have noticed that the boost only fluctuates heavily on the climb up the RPMs and stabilizes at .11MPA (15.995ish PSI) as I approach redline. Between 4-5k especially it swings from 12psi to .13 MPA (18.85 psi) back and forth, and then again, evens out at redline to 16lbs.

When I have talked to Vishnu, they claim that I must have accidentally hit a hose or something or other when taking out the resonator (although i doubt it as it is a simple procedure next to basically no vaccum lines and I have already checked them all). They ARE sending me a new vaccum line between the boost control solenoid and the turbo, so I will try that out when it gets to me...
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Old 08-26-2007, 09:03 AM   #16
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You might want to check out Pro-Motion tuning in fredricksburg. I just got back from there. They do nothing but Open source tuning. 95 Bux an hour on the dyno. I can log your car if you want. I'll pm you my number.
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Old 08-26-2007, 11:10 AM   #17
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sounds to me like the wastegate duty cycles aren't stepping down at the proper rpm or the dynamics are too aggressive.
Good luck on getting it fixed. Wish I could help more, but I'm way over here.
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Old 08-28-2007, 02:36 PM   #18
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i have the same problem, got my car tuned with the tactrix on enginuity and have the exact same fluctuations my tuner put the stock perameters for the solenoid to 19lbs, cant figure it out myself
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Old 08-28-2007, 02:44 PM   #19
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there are 2 maps for the wg duty cycle, ive seen cars w/ 2 seperate maps in them and fluctuation happens because the ecu is cycling through the 2 maps. dunno why.. set both maps the exact same, you can copy and paste. you might get rid of ur fluctuation.
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Old 08-30-2007, 12:45 PM   #20
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Quote:
Originally Posted by javastiwagon24 View Post
i have the same problem, got my car tuned with the tactrix on enginuity and have the exact same fluctuations my tuner put the stock perameters for the solenoid to 19lbs, cant figure it out myself
that's the problem.
you can't run stock parameters once the exhaust is modified.

Back pressure in the exhaust is one of the many factors that affect the wastegate performance. Once that is modified, you have to adjust the wastegate settings.
Most subys have more than 2 wastegate maps.
Usually you find:
Initial wastegate duty cycle. 3D map of RPM vs TPS. The starting point for boost control, before compensation factors are used. (between 1 and 4 of these maps)
Max wastegate duty cycle. 3D map of RPM vs TPS. The max WGDC before compensation factors.(usually just one for MT and one for AT)
Max wastegate duty. One value that is a global limit.
Wastegate duty trim based on IAT. 2D map of IAT and a modifier added or subtracted to previous maps.
Wastegate duty trim based on Coolant temp. 2D map of Coolant temp and wastegate modifier. Not always used.
Wastegate duty trim based on Barometric pressure. another 2D compensation map.
and there's more in some cars...

Then you have turbo dynamics. This is how the ecu calculates where to go with the wastegate duty cycles. These are based on boost error and the nature of the boost control. whether it's static control or dynamic control. (boost is being stabilized at target boost or target boost is trying to be achieved).
There are between 2 and 12 maps for turbo dynamics based on the ecu in question.

Tuning these on the street can be tricky. Getting on a load bearing dyno where you can lock in a speed is the best way to get all the dynamics taken care of in multiple RPM increments.

If the car has stable boost one day and not the next, it can usually be an easy adjustment to the wastegate trim based on IAT.
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Old 08-30-2007, 03:12 PM   #21
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Got the same problem with a AP v1 with an e-tune from TDC tuning.
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Old 08-31-2007, 01:15 PM   #22
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i had a problem like that... i just looked over all my hoses on the turbo and found out that something was hooked up wrong :X
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Old 08-31-2007, 01:39 PM   #23
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all hoses are fine on mine...even replaced most of the ones conected to the trubo and the stock BCS...
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Old 09-17-2007, 08:32 PM   #24
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so i can't decide whether its a physical problem like a boost leak or spike or missing restrictor pill etc etc, or whether its a mapping problem.

Clue: Car runs rich enough to backfire consistantly upon downshifting...any takers?
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Old 09-17-2007, 11:44 PM   #25
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what you need to do is buy a tactrix cable! then upload your current file, then go into the turbo dynamics folder, after that you chose the first to files under tdynamics and make all the settings that are in positive to zero, i did this last week and my osilations have basically disapered.
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