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Old Oct 14, 2009, 04:21 PM
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PSI Based Boost issue...

Interesting situation, I have MFRED's ECU Based Boost. Local pressure is 12.6, boost table shows 23.5 psi tapering to 19 psi at red.

Vacuums are good, holds Idle at 14 vacuum. Boost seems to hit its limit @ 21... I don't hit fuel cut, boost just won't go past it.

I have checked for boost leaks, and can't find any.

Boost limit is set at 27 tapering to 24.5....

I still have my BDEL in my code.

Here is my mapping:

Any ideas? Thanks in advance.
Attached Thumbnails PSI Based Boost issue...-boost.wgdc.boostlimit.jpg   PSI Based Boost issue...-timing.jpg  

Last edited by Raceghost; Oct 14, 2009 at 04:32 PM.
Old Oct 14, 2009, 04:35 PM
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whats is your psi boost adder?
or load adder?
Old Oct 14, 2009, 04:51 PM
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whats is your psi boost adder?
or load adder?
I have it set to local pressure of 12.6. As long as i don't want to boost over 24 psi, I followed MFred's instuctions as per the walkthrough. Boost Addr is 12.6, guage pressure or Baseline Boost, is set to 23.5...
Old Oct 14, 2009, 09:24 PM
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log boost (or load) error to see the whole story.
Old Oct 15, 2009, 08:22 AM
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I have been logging the Boost Error, it gives me a few negative numbers. While in cruise, my Map Sensor states vacuum, and the Boost Error states -3.087.

When I go open throttle, those negative numbers change. The omni 4 bar is registering 22.7 for one cell, and the boost error is 0.745, this would suggest the car is hitting the 23.5 Boost settings that I have. Unfortunatly, it starts to bleed off, numbers stay positive, but shows that Boost is tapering off.

On my guage I only see 21, does this mean I am hitting my peak numbers that I want? Seeing a boost error negative and positive like that?

Thanks in advance
Old Oct 15, 2009, 08:53 AM
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can you post the log or graphs during a pull, it is hard to understand through explanation.

I would trust the MAP sensor over gauge reading.
Old Oct 15, 2009, 08:54 AM
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Can you post a log with wastegate duty cycle and boost pressure?

If you want to see what it can do, just set your baseline wastegate duty cycle table to 100% across the board and set all of the boost desired tables to max, add in some boost adder and set all the boost error compensation tables to 0.

This gets another Wasatch front IX EVO 32+ PSI that eventually tapers down to like 23 psi.

*not recommended for 91 octane*
Old Oct 15, 2009, 08:56 AM
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Originally Posted by 03whitegsr
Can you post a log with wastegate duty cycle and boost pressure?

If you want to see what it can do, just set your baseline wastegate duty cycle table to 100% across the board and set all of the boost desired tables to max, add in some boost adder and set all the boost error compensation tables to 0.

This gets another Wasatch front IX EVO 32+ PSI that eventually tapers down to like 23 psi.

*not recommended for 91 octane*
oh my, that sounds very dangerous...
Old Oct 15, 2009, 09:31 AM
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Originally Posted by Raceghost
I have been logging the Boost Error, it gives me a few negative numbers. While in cruise, my Map Sensor states vacuum, and the Boost Error states -3.087.

When I go open throttle, those negative numbers change. The omni 4 bar is registering 22.7 for one cell, and the boost error is 0.745, this would suggest the car is hitting the 23.5 Boost settings that I have. Unfortunatly, it starts to bleed off, numbers stay positive, but shows that Boost is tapering off.

On my guage I only see 21, does this mean I am hitting my peak numbers that I want? Seeing a boost error negative and positive like that?

Thanks in advance
Sounds like you need more duty cycle then.

Set your desired boost and boost curve using WGDC, without any correction. Then use the correction tables to keep everything in check.
Old Oct 15, 2009, 09:54 AM
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Are you sure that local pressure is 12.6psia? That seems really low ...

Have you tried using the standard 14.6psia for the adder to see if it helps? Also, is your WGDC% maxxing out where you want the 23 psi boost?

Negative boost error means that the ECU will increase the WGDC% ... you're under your target. Positive error means you are over your target and WGDC% is lowered. Your example ...

The omni 4 bar is registering 22.7 for one cell, and the boost error is 0.745, this would suggest the car is hitting the 23.5 Boost settings that I have.
You're thinking backwards. If you are logging 22.7 psi and have an error of .745, then that's saying that the ECU sees 22.7 as above target and will pull WGDC% to lower the boost. the logged boost is actual psi ... you don't add or subtract the error. The error is a reflection of actual boost v. desired boost (Boost Adder + Baseline Boost).

You need to increase the boost target to reach your goal.

Last edited by TouringBubble; Oct 15, 2009 at 09:59 AM.
Old Oct 15, 2009, 09:59 AM
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Originally Posted by TouringBubble
Are you sure that local pressure is 12.6psia? That seems really low ...
Not for Salt Lake City. It's at 4200'.

In Albuquerque, atmospheric is usually down around 11.9 psi. At Sandia crest, on the edge of town here it's down around 10.2 ( > 10,000').

d
Old Oct 15, 2009, 10:45 AM
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AVERAGE SLC pressure is 12.4 PSIA

12.6 is actually a GOOD day

12.2 is the low

Locking the wastegate is definitely "dangerous" but it will also show if the turbo is the limit or not.
Old Oct 15, 2009, 11:04 AM
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Logging the WGDC% will show the same thing ... much more safely.
Old Oct 15, 2009, 01:06 PM
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Read the first line of my original post.

I also said specifically, "If you want to see what it can do" and included a little note that it's not to be done on crap fuel.

Man, I guess this is America, apparently everything has to have idiot labels...
Old Oct 15, 2009, 05:44 PM
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Ok guys, I have located the issue, and added more WGDC. Here is the logs, and here is the settings:

Edit:These are the adjusted logs which I hit 23 on the dial today, when doing these pulls.

I am only seeing knock up in the high end, approx. 6K as it shows in the log.

But it doesn't make sense, the higher the rpm, the lower the load cells....?

Also I noticed when I log, that sometimes, I pull a full 3rd gear to red line, but will only capture a few seconds of the readings.... Thought it was due to the wideband, but still I get issues in the log missing data that it should have captured. It as though EVOscan pauses for a second, like it is overloaded....just an observation. Also my octane reading states 100 octane, I am on 91 from Chevron...no clue on this either.

Thanks guys
Attached Thumbnails PSI Based Boost issue...-currentsettings.jpg   PSI Based Boost issue...-currentlog.jpg  

Last edited by Raceghost; Oct 15, 2009 at 08:31 PM.


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