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OverBoosting and / or Underboosting, whats missing?

Old Apr 14, 2012, 08:17 PM
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OverBoosting and / or Underboosting, whats missing?

UPDATE *********

narrowed the behavior down,
for the most part in any normal AP map (93@ stg 1/2 +sf) the car overboosts hard in first, second, third, and sometimes fourth (usually upon initial WOT)

With any LWG map the car reaches target boost in first gear (24-26) and pulls nicely but then underboosts in the rest of the gears, will hold 20psi firmly in 3,4, and 5th at any point in the rpm range... so although its nice in first its slow and unresponsive in the rest of the gears, to the point that the factory tune in those gears pulls much smoother and harder.

not sure if that helps...
I can log with any map if someone can decipher what is happening. just let me know which parameters to log



ORIGINAL POST**************
(posted this in general engine management because im not sure the problem is in anyway related to the AP)

Hey guys, I know the factory tune is crappy and have had lots of the usual overboost or torque limit jerking and what not overfueling crap... needless to say,
my current mods are Buschur cat back, Cobb SF intake, and just reinstalled the AP.
with the ap on a stages 1/2 map (+sf) @ 93/91 I boost spike in first, second, and sometimes third or fourth.
with the stage 2 (+sf) @ 93 LWG I hit 26 psi smoothly in first feels great and then the boost tapers in each gear in third and fourth im only holding 15-20 or so through the 3-6k RPM range.
So reading the map notes (they are the same for all stage 2 maps) it says "with wg boost restrictor pill removed"

would having the boost restrictor pill in cause this overspiking issue or be the reason I dont reach target pressures?

To clarify the car behaved this way with the stock tune and would sometimes throw the ASC! service engine light. but it was usualy not as harsh, it would just feel like randomly durring hard acceleration you would suddenly lose 100HP and then 1000-2000 RPM later you would gain them back. I was hoping the COBB tune would take care of this but is it perhaps related the Boost restrictor pill (with the stg 2 lwg map) or might I have another issue?

thanks all in advance!

Last edited by HELPr; Apr 18, 2012 at 09:15 PM. Reason: Clarified post / Update
Old Apr 17, 2012, 06:27 PM
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It sounds like your boost control is hooked up wrong or you have a 3 port installed.

Take a picture of your boost control setup. It's located next to the red thing with a + on top, drivers side, by the fire wall.
Old Apr 18, 2012, 08:51 PM
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Originally Posted by Golden
It sounds like your boost control is hooked up wrong or you have a 3 port installed.

Take a picture of your boost control setup. It's located next to the red thing with a + on top, drivers side, by the fire wall.
Both ports pointing towards the enging (1upper 1 lower) are T'd into the line that connects the wastegate and the bov piping (not bov vaccume port) both of these hoses 4" long roughly contain a restrictor pill prior to the dedcution 'Y'

The other two ports pointing to the fire wall (upper and lower) are Y'd and then run into the intake piping.

hope thats a good enought description.
I can get a picture to you tomorrow if necessary.

Thanks! Appreciate the help.
Old Apr 19, 2012, 08:19 PM
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Could someone look at a log for me and tell me if perhaps something is out of the ordinary?
let me know what to log and I will post Logs.
thx

Should I pull of the COBB SF filter and put the stock box back on?
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