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Looking at my recent StgII boost graph, I'm concerned by my high WG duty cycle in the upper RPM's. I suppose this would point to either a boost leak or a failing turbo. Is this a good guess?

 

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Discussion Starter · #3 ·
I'm sorry, the wastegate duty cycle curve is in yellow, I thought that would be obvious. Which boost curve is actual or requested is irrelevant being that they are so close.
 

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:screwy: the car has to request boost before it starts making it lol, so its not relevant as long as you know what your actually looking at!

red- his actual
blue- his requested value.

Was this log taken when it was warm out above 78*F?

I wouldnt say its a boost leak or failing turbo the turbo has to work near/ over peak efficiency in the higher rpm's because the ko3s is soooo smallll. I wouldn't look into to hard as IMO everything seems ok. you're only slightly short of requested and by the looks of things I'd say your running Revo software also?
At ther worst from your limited info you gave about the graph it was either hot, you have the stock fmic, or you have a pinhole leak in either the dv/ pcv either way like I said its not a huge deal.
 

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I know what I am looking at. He stated that it isn't relevant because the two curves are so close and it is relevant even if you have to decipher the info. If the red is the actual then it is a small leak for sure. From what I have always seen the actual should always be a little bit above requested and the wastegate cycle is way too high for a k03 requesting 12 psi towards redline.
 

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Discussion Starter · #7 ·
:screwy: the car has to request boost before it starts making it lol, so its not relevant as long as you know what your actually looking at!

red- his actual
blue- his requested value.

Was this log taken when it was warm out above 78*F?

I wouldnt say its a boost leak or failing turbo the turbo has to work near/ over peak efficiency in the higher rpm's because the ko3s is soooo smallll. I wouldn't look into to hard as IMO everything seems ok. you're only slightly short of requested and by the looks of things I'd say your running Revo software also?
At ther worst from your limited info you gave about the graph it was either hot, you have the stock fmic, or you have a pinhole leak in either the dv/ pcv either way like I said its not a huge deal.
Thanks for the worthwhile response...
I did take this log when it was quite hot out, about 85F. I didn't know that WG duty cycle tends to peg in the later RPM's when its hot out, I only know that usually my WGDC is around 60% from 5000rpm onward with this program, which is the latest APR SII non-HPFP file. I was also under the impression that a pegged WG in the upper RPMs created high EGTs, and that in a healthy boost/vacuum system, some of the exhaust flow is always diverted at high RPMs.

Why would the N75 need to provide more exhaust flow to maintain boost levels in hot ambient conditions? :confused:
 

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Thanks for the worthwhile response...
I did take this log when it was quite hot out, about 85F. I didn't know that WG duty cycle tends to peg in the later RPM's when its hot out, I only know that usually my WGDC is around 60% from 5000rpm onward with this program, which is the latest APR SII non-HPFP file. I was also under the impression that a pegged WG in the upper RPMs created high EGTs, and that in a healthy boost/vacuum system, some of the exhaust flow is always diverted at high RPMs.

Why would the N75 need to provide more exhaust flow to maintain boost levels in hot ambient conditions? :confused:
APR has plagued myself with the way my car ran, I ran near peak wgdc for over a year on my ko3 but I was making 14-16psi at redline. My EGTs were still within reliable temp ranges by all the tests I ran post turbo with a tail pipe egt probe. Allbeit not the most accurate but before I sold my car I had 67k on it and i had the turbo off to pull my forge wg off and the turbo still showed little shaft play.

Next 99% wgdc does not mean that the WG is physically pinned shut, so your correct in thinking "some of the exhaust flow is always diverted in the higher rpm's." 99% wgdc is just what the car thinks 99% efficiency is going to be at that point and engine speed.

Lastly the n75 needs to provide more exhaust flow to maintain boost levels in hot ambient conditions because the turbo has to work harder by sucking in less dense hot air molecules to make the same amount of pressure that it could with more dense air "cooler air" while doing less work.

:beer:


I know what I am looking at. He stated that it isn't relevant because the two curves are so close and it is relevant even if you have to decipher the info. If the red is the actual then it is a small leak for sure. From what I have always seen the actual should always be a little bit above requested and the wastegate cycle is way too high for a k03 requesting 12 psi towards redline.
Actual should never be over the requested value much less always be on a stock turbo, stock hpfp mkv.
 

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I've been having a similar problem.
My actual is about 1~2 psi lower then requested after 4k rpm and WG cycle is at 90%.
I've recently bough a "D" dv, EJ PCV fix and T-clamps instead of regular hardware store clamps (for my S3 IC) to see if I can fix the problem.
 
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