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Old 11-14-2012, 02:32 AM   #1
gwilliamson
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Default Help 2002 Wrx Not Holding Boost?!

Hey guys so I just got my first turbo car (2002 wrx) While doing some decent pulls I noticed on my Turbo gauge it spikes then drops and spikes and drops. What do you think this could be mods are:

Cobb v.1 accessport stage 2 93 oct map
Kartboy s/s
Forge recirc valve
K&N panel filter
Catless up pipe (ebay brand)
Catless turbo back exhaust (ebay brand)
Oil/air separator
Cx racing alum. radiator
Jna turbo timer
Turbo blanket
Silicone turbo inlet
Front+rear strut tower braces
H-brace sub support

(i know most of them definitely have nothing to do with it just giving you the whole low down)

PLEASE HELP A NOOB THANKS
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Old 11-14-2012, 02:55 AM   #2
TwoFifty
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Fluctuating boost is usually caused by a boost leak. Get the system pressure tested and fix your leaks then go from there.
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Old 11-14-2012, 07:37 AM   #3
wrxlaunch
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Did it just start doing this with the temp change?
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Old 11-14-2012, 12:45 PM   #4
gwilliamson
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how would you recommend getting it pressure tested?
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Old 11-16-2012, 01:52 AM   #5
gwilliamson
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At WOT in 5th gear especially I can feel the car loose boost over and over again as well as the gauge. The car holds perfect boost around 10 psi but once it hits 14/15 it will drop and go back and drop and go back. (Definitely not just a gauge problem) :/

ANY RECOMMENDATIONS?
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Old 11-29-2012, 01:05 AM   #6
gwilliamson
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it hits anywhere between 15/20! BUMP AND DROPS
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Old 11-29-2012, 09:59 AM   #7
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Quote:
Originally Posted by gwilliamson View Post
At WOT in 5th gear especially I can feel the car loose boost over and over again as well as the gauge. The car holds perfect boost around 10 psi but once it hits 14/15 it will drop and go back and drop and go back. (Definitely not just a gauge problem) :/

ANY RECOMMENDATIONS?
Dude, never go WOT in 5th gear! Most cars are tuned for 3rd, higher gears will cause you to overboost!
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Old 11-29-2012, 11:26 AM   #8
bushflyr
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Quote:
Originally Posted by jthatch12 View Post

Dude, never go WOT in 5th gear! Most cars are tuned for 3rd, higher gears will cause you to overboost!
What? Dude. You have no idea what you're talking about. Cars are turned in third because they won't make full body in second and they don't want the dyno going 130 mph in fourth. It has nothing to do with the fifth gear boost.

Any tune will hold proper boost in all gears.
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Old 11-29-2012, 12:22 PM   #9
ogboot
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Quote:
Originally Posted by bushflyr View Post
What? Dude. You have no idea what you're talking about. Cars are turned in third because they won't make full body in second and they don't want the dyno going 130 mph in fourth. It has nothing to do with the fifth gear boost.

Any tune will hold proper boost in all gears.
Eh, you're both kind of right really. You touched on it a little bit; you don't need to go WOT in 5th unless you're at a pretty significant speed. From a common interstate speed, WOT is a bad idea in fifth. This is even more relevant to the 16bit ECU as it doesn't have per gear compensation.

And most cars are tuned for 3rd/4th whether it's a dyno tune or road tune. A car tuned for solid XXPSI in 3rd/4th will usually overshoot the boost target a bit in 5th on the stock boost control management.

@OP: Oscillating boost is an indication that you're overshooting your boost target. Talk to the original owner and find out who tuned it, or if it's even tuned at all. Then talk to the tuner. If it's not tuned, then yeah really talk to a tuner, and stop going WOT.

If the cars tuned, it may be because of the colder weather and you may just need to loosen the wastegate arm a little bit. Get more info on the car first though. Is it just the COBB ots map?

Here's a good rule of thumb. WOT on the interstate? drop it down to 4th at least. Not enough gear in 4th to downshift and go WOT? You're already going too fast! 4th gear tops out north of 100mph... Hell 3rd gear can get you to something like 80 if i'm not mistaken. Plus, EGTs start to be come questionable on most tunes after a hard 4th gear pull anyway.

Last edited by ogboot; 11-29-2012 at 02:30 PM.
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Old 11-29-2012, 05:56 PM   #10
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Quote:
Originally Posted by ogboot View Post

Eh, you're both kind of right really. You touched on it a little bit; you don't need to go WOT in 5th unless you're at a pretty significant speed. From a common interstate speed, WOT is a bad idea in fifth. This is even more relevant to the 16bit ECU as it doesn't have per gear compensation.

And most cars are tuned for 3rd/4th whether it's a dyno tune or road tune. A car tuned for solid XXPSI in 3rd/4th will usually overshoot the boost target a bit in 5th on the stock boost control management.

@OP: Oscillating boost is an indication that you're overshooting your boost target. Talk to the original owner and find out who tuned it, or if it's even tuned at all. Then talk to the tuner. If it's not tuned, then yeah really talk to a tuner, and stop going WOT.

If the cars tuned, it may be because of the colder weather and you may just need to loosen the wastegate arm a little bit. Get more info on the car first though. Is it just the COBB ots map?

Here's a good rule of thumb. WOT on the interstate? drop it down to 4th at least. Not enough gear in 4th to downshift and go WOT? You're already going too fast! 4th gear tops out north of 100mph... Hell 3rd gear can get you to something like 80 if i'm not mistaken. Plus, EGTs start to be come questionable on most tunes after a hard 4th gear pull anyway.
I was gonna mention unless you're going 120+ but I figured most people arent that dumb on public roads.....

and 3rd gear tops out in the high 90s... I've done a lot of 3rd gear pulls for tuning
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Old 11-30-2012, 01:17 PM   #11
gwilliamson
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thanks for the input! I am going to take it out tonight and go wot in 3rd and see if it over boosts.

It is tuned with a Cobb Accessport stage 2 93 oct

(1st generation accessport)
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Old 11-30-2012, 01:22 PM   #12
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Quote:
Originally Posted by jthatch12 View Post
Dude, never go WOT in 5th gear! Most cars are tuned for 3rd, higher gears will cause you to overboost!
Wrong. Very ignorant comment with no support or evidence. What do you base this comment on? If your car can make boost in one gear, it should work in any gear. Period. If not, something is very wrong.

Quote:
Originally Posted by bushflyr
What? Dude. You have no idea what you're talking about. Cars are turned in third because they won't make full body in second and they don't want the dyno going 130 mph in fourth. It has nothing to do with the fifth gear boost.

Any tune will hold proper boost in all gears.
Most cars are tuned in 4th gear because that gear, in most cars, is a direct drive, meaning there is a 1:1 ratio, no torque multiplication. You could tune in first gear if you wanted, but it would be really quick and most likely, the 2600lb/ft of torque produced by 217lb/ft x 3.5xx first and a 3.54 final drive would spin the tires on the dyno rollers. That is the ONLY reason higher gears are used for dyno, the 1:1 gear ratio.

OP: I am having this same problem right now, but I'm waiting to have my car tuned. I have essentially a Vishnu stage zero kit installed.

Last edited by car_freak85; 11-30-2012 at 01:48 PM.
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Old 11-30-2012, 04:41 PM   #13
ogboot
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Quote:
Originally Posted by gwilliamson View Post
thanks for the input! I am going to take it out tonight and go wot in 3rd and see if it over boosts.

It is tuned with a Cobb Accessport stage 2 93 oct

(1st generation accessport)
Check with Cobb, I bet that map doesn't officially support the aftermarket turbo inlet either. Cobb's maps support turboback, intake or drop-in filter, and that's about it. When I put my inlet on I had to rescale my MAF because the car was running lean in boost and overboosting.

This map might be right up your alley, from their site: " Low Wastegate - For vehicles exceeding target boost". Protune would be better.

But really, continuing to go WOT isn't going to fix a thing. Quite the opposite.
Your mod list does not include a wideband O2 sensor, so you don't have a clue what your AFR is doing. Don't bother looking at the AP because it's just reading off of the stock sensor and it's likely not going to be correct.
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Old 12-06-2012, 10:44 AM   #14
gwilliamson
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thanks man ill try that map!
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Old 12-06-2012, 04:10 PM   #15
Tenament
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Do you have the factory boost solenoid installed still?

That's your reason why if so.
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