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 Post subject: Manifold pressure (corrected) not matching target boost
PostPosted: Sun Mar 16, 2025 5:52 pm 
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Joined: Sun Mar 16, 2025 5:27 pm
Posts: 14
My mods are:
3" full catless exhaust w/ EL headers (new mods needing tune)
ID 1000cc injectors
FP blue turbo
stock heads w/ upgraded springs
IAG 750 built block
Cobb 3 bar map sensor (older oem style)

Hi all, I'm a tune newbie slowly getting things started. My 2006 wrx was originally locked to an AP so I had to start making a tune from scratch. I got the car running, driving and idling but I'm trying to dial in WGDC, boost and VE table but for some reason the map sensor is reading different than my boost gauge and target boost. I have a few logs to show what the issue is (not all till redline, still have knock to deal with I think I got bad 93)

My boost gauge has seemingly been accurate, when I was running 0 WGDC it read 15 psi (spring) and reads 19-20 psi now, It's tee'd into the bpv line. I don't know what the issue is, or maybe there isn't one?


Attachments:
romraiderlog_20250316_160801.csv [9.85 KiB]
Downloaded 14 times
romraiderlog_20250316_160911.csv [9.28 KiB]
Downloaded 9 times
romraiderlog_20250316_162756.csv [7.55 KiB]
Downloaded 8 times
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 Post subject: Re: Manifold pressure (corrected) not matching target boost
PostPosted: Thu Mar 27, 2025 3:45 pm 
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Joined: Sat Jul 06, 2013 8:55 am
Posts: 3264
Location: NI
what happens if you log absolute manifold pressure and absolute target? also what's your map reading like at idle compared to your boost gauge and are you 100% sure you have the correct map sensor scaling / offset plugged in for that map sensor?

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Good luck and may the logs be ever in your favour!


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 Post subject: Re: Manifold pressure (corrected) not matching target boost
PostPosted: Fri Mar 28, 2025 2:35 pm 
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Joined: Sun Mar 16, 2025 5:27 pm
Posts: 14
bludgod wrote:
what happens if you log absolute manifold pressure and absolute target? also what's your map reading like at idle compared to your boost gauge and are you 100% sure you have the correct map sensor scaling / offset plugged in for that map sensor?


Hi Bludgod thank you for your time. I got a log of the parameters you requested, I also removed unnecessary stuff. At idle, the gauge reads -10.4 psi while the map sensor reads -9 psi. As for the scaling, cobb's website gave me "calibration: Multiplier = 14.504 psi Offset = -7.252 psi" which I used. The only thing I can think of is my WGDC isn't high enough, I heard 32 bit cars can be quite picky. I will upload my rom if anyone wants to take a look

https://www.mediafire.com/file/uqz6zq8b ... D.hex/file


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romraiderlog_20250328_135851.csv [6.47 KiB]
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 Post subject: Re: Manifold pressure (corrected) not matching target boost
PostPosted: Fri Mar 28, 2025 10:27 pm 
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Joined: Sat Jul 06, 2013 8:55 am
Posts: 3264
Location: NI
for your log - check your romraider settings for "fast polling" and make sure its enabled. But looking at your log i would imagine turbo dynamics and wastegate duty tables need looking at is you get close to target boost then your wastegate duty drops to like 20% and your boost drops with it.

but if the absolute values aren't matching your gauge either it's also possible your gauge is off a bit - it's rare to find a gauge you can buy off the shelf that reads as accurately as the ECU's map sensor.

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Good luck and may the logs be ever in your favour!


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 Post subject: Re: Manifold pressure (corrected) not matching target boost
PostPosted: Fri Mar 28, 2025 11:31 pm 
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Newbie

Joined: Sun Mar 16, 2025 5:27 pm
Posts: 14
bludgod wrote:
for your log - check your romraider settings for "fast polling" and make sure its enabled. But looking at your log i would imagine turbo dynamics and wastegate duty tables need looking at is you get close to target boost then your wastegate duty drops to like 20% and your boost drops with it.

but if the absolute values aren't matching your gauge either it's also possible your gauge is off a bit - it's rare to find a gauge you can buy off the shelf that reads as accurately as the ECU's map sensor.


I think you are absolutely correct, seems it isn't that accurate and there isn't really a good way to test it either. Super appreciate the advice I will look into those next, I would've kept chasing tails and issues in the wrong places :lol:


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