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Old 11-29-2012, 10:12 AM   #1
DSM Goat
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Default Boosting Late but Strong

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My tuner is telling me that boost is coming on late and that he, "can't control it." He has, "turned the boost all the way up." He said to expect between 20-25 lbs of boost @ redline. And that's exactly what I get.

However, boost doesn't start until around 2800-3000 RPM. But once boost builds, it boosts all the way to 22-25 lbs @ redline.

So I need to figure out why I'm boosting late before my tuner can continue tuning.

I've read several threads on this and most point to a boost leak as the most likely culprit. But if I'm boosting all the way to 22-25 lbs (not losing boost), is boost leak still the most likely cause of my late boost?

I appreciate your guys thought on this.

Thanks.
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Old 11-29-2012, 10:38 AM   #2
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So you dont get power as it builds quickly..then bam 25psi?
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Old 11-29-2012, 10:56 AM   #3
DSM Goat
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No boost until ~ 3000 RPM, then boost kicks in and builds to 22-25 lbs by the time I'm at redline.
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Old 11-29-2012, 10:57 AM   #4
tachrev
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So, you have 0psi until 2800-3000?

What do you mean by boost doesn't start until 2800-3000?

What gear are you testing this in?

Can you post a log?
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Old 11-29-2012, 11:02 AM   #5
DSM Goat
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Actually - (vacuum) psi until 2800-3000.

So, what I mean is that yes, NO boost ~ 3000 RPM. At that point boost begins to build until I'm at 22-25 lbs @ redline in 3rd gear.

My tuner is having me do AP logs and has instructed me to do third gear @ 2000 RPM WOT pulls to redline.
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Old 11-29-2012, 11:08 AM   #6
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Wait to see what the tuner says.
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Old 11-29-2012, 11:10 AM   #7
DSM Goat
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The tuner is telling me I need to figure out why I'm boosting late before he can complete my tune.
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Old 11-29-2012, 11:54 AM   #8
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Quote:
Originally Posted by DSM Goat View Post
The tuner is telling me I need to figure out why I'm boosting late before he can complete my tune.
Try a 3-port electronic boost solenoid?
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Old 11-29-2012, 12:00 PM   #9
JUICEB0X
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Maybe someone swapped a bigger turbo in without you knowing.
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Old 11-29-2012, 12:09 PM   #10
DSM Goat
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I put the VF48 on myself, along with all the other work. I just don't know how to tune.
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Old 11-29-2012, 12:21 PM   #11
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You say boost builds to redline, does that mean you aren't reaching target boost until redline? At what RPM are you achieving max boost?

It sounds like a boost leak or a pre turbo exhaust leak. They both won't always prevent you from hitting your boost target but they will make the turbo work harder to do so and boost response will be slower.
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Old 11-29-2012, 12:25 PM   #12
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Sounds to me like there is an issue with your BCS. Also on a vf48 there is absolutely no way you can hold 25psi to redline it's completely out of the turbos efficency range, at the point you're doing much more harm then good. If you don't mind me asking who is the tuner? A log will be the best way to really analyse your issue, but I'd also get a boost leak tester (simple search of this and you can do it for around $30 and a trip to lowes).
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Old 11-29-2012, 01:37 PM   #13
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I went home and looked at my logs...I'm hitting max boost (19.7 lbs) @ 5300 RPM. I was trying to recreate from memory, but I was off a bit - not 25lbs, but 19.7 lbs.

And I am starting to boost @ 2100 RPM (2 lbs). But I don't get into double digit boost (10.4 lbs) until ~ 3000 RPM.

Sorry for the confusion. I can post my logs when I get off work.
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Old 11-29-2012, 02:43 PM   #14
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boost or exhaust leak. My 2 cents
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Old 11-29-2012, 02:48 PM   #15
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What do you have between the motor and the turbo on the exhaust side? Boost starting at 2100 rpm does not sound late to me.
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Old 11-29-2012, 02:59 PM   #16
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EL headers and an Invidia Up-Pipe.
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Old 11-29-2012, 03:20 PM   #17
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Quote:
Originally Posted by DSM Goat View Post
EL headers and an Invidia Up-Pipe.
And are they leaking at any of the 4 flanges? and is the EGT plug in the uppipe?
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Old 11-29-2012, 03:28 PM   #18
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The plug's in the up-pipe. But I will make sure the flanges are tight. Thanks for the advice!
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Old 11-29-2012, 04:11 PM   #19
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Quote:
Originally Posted by DSM Goat View Post
I went home and looked at my logs...I'm hitting max boost (19.7 lbs) @ 5300 RPM. I was trying to recreate from memory, but I was off a bit - not 25lbs, but 19.7 lbs.

And I am starting to boost @ 2100 RPM (2 lbs). But I don't get into double digit boost (10.4 lbs) until ~ 3000 RPM.

Sorry for the confusion. I can post my logs when I get off work.
Building boost at 2100 is normal, 10.4 at 3000rpm is not bad, your problem is from 3000rpm-6500rpm. You should hit 19.7 at 3800. I assume you are not getting the additional 9.3psi from 3000rpm-4000rpm are you?

Its sounds as simple as a leak. Check exhuast connections.
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Old 11-29-2012, 04:44 PM   #20
DSM Goat
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@3800 = 15 lbs.

@3000 = 12.2 lbs

@4000 = 15.5 lbs
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Old 11-29-2012, 05:04 PM   #21
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Maybe it's me but from what i'm reading it seems as if boost is coming on normal.

Mike
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Old 11-29-2012, 05:10 PM   #22
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Quote:
Originally Posted by GrimmSpeed View Post
Maybe it's me but from what i'm reading it seems as if boost is coming on normal.

Mike
Yeah doesn't sound horrible to me for a 2.0L car. You probably can get it to spool quicker but its could just be in the tuning (timing). Make sure you tell your tuner its a 2.0L and not a 2.5L motor!
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Old 11-29-2012, 05:23 PM   #23
ogboot
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Quote:
Originally Posted by GrimmSpeed View Post
Maybe it's me but from what i'm reading it seems as if boost is coming on normal.

Mike
Ditto. VF48 on a 2.0L
Hit this guy up for an EBCS if you want it to spool faster.
Disclaimer: will require retune.

Last edited by ogboot; 11-29-2012 at 05:32 PM.
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Old 11-29-2012, 06:16 PM   #24
DSM Goat
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Here's a log of a WOT 2k to redline pull. Let me know what you think.

https://docs.google.com/open?id=0B6Y...DE3ci1jNWJmZ1k
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Old 11-29-2012, 06:27 PM   #25
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Link does not work
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