Boost leak test with MBC question. Etc - Dodge SRT Forum
 
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post #1 of 6 (permalink) Old 05-22-2019, 02:31 PM Thread Starter
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Boost leak test with MBC question. Etc

Sooooo this is an on going thing with my car for over a year now, thought I would ask here. Car is a 50 AGP trim all solenoids deleted boost contolled via manual boost controller.

Car originally had a Perrin MBC. My tuner told me it is junk. I noticed it would whistle during a boost leak test. It has a bleed port on it was told that was normal. So I went with a Hallman MBC. They are known to be the best. But everytime I do a boost leak test that thing whistles like crazy at 10psi. So I can't really get past 15psi due to it bleeding like crazy during the test. Just remove it when doing boost leak test I guess.

So I noticed when driving my car my boost needle shakes like it has tourettes at 22-24psi @ WOT. This is what I have my MBC set to. I am guessing this is due to the MBC bleeding out boost? I had issues holding boost and my tuner (Duster360) told me to put another Tial spring in my Tial 38mm wastegate. (you can compound the springs)

So my 38mm has like 21lbs worth of springs in there. It holds boost fine, but the needle shakes on the boost gauge when going WOT and hitting peak boost. Is this a normal occurence with a MBC due to it bleeding? Does having the stiffer WG springs affect anything?

Hallman offers a stiffer MBC spring. Would that help? I emailed them and they said it wouldn't do much of a difference.

Since my WG has 21lbs worth of springs couldn't I just remove the boost controller and run just off the WG pressure if I just wanted 21lbs?

Thanks guys for any help. Car runs fine and made good power with the needle "shaking" like that so I am thinking it is normal. Just new to the world of MBC. Used to PCM controlled setups.

05 PW1 SRT-4
AGP 50 trim and supporting mods
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post #2 of 6 (permalink) Old 05-23-2019, 05:41 AM
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if your wastegate has 21psi spring, then yes you can run without a boost controller and should see 21psi. There are other things to consider when you are trying to diagnose the needle shaking... what brand gauge?


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post #3 of 6 (permalink) Old 05-23-2019, 01:12 PM Thread Starter
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Good to know about not having to run a MBC with those WG springs.

Its a OEM style Autometer 30/30. I recently got a Aeroforce scan gauge and I have boost set up on that where it reads at the MAP sensor. Going to see if it fluctuates on that too. Could just be the boost gauge or a leak to the boost gauge. But when I had the dash apart it was clamped on there good. But who knows might have a needle leak or something. Would have to boost leak test the car with the dash up to see if it is leaking at the gauge. Sorry for the ramble in my original post.

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post #4 of 6 (permalink) Old 05-23-2019, 01:45 PM
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Originally Posted by s3*ps2 View Post
Good to know about not having to run a MBC with those WG springs.

Its a OEM style Autometer 30/30. I recently got a Aeroforce scan gauge and I have boost set up on that where it reads at the MAP sensor. Going to see if it fluctuates on that too. Could just be the boost gauge or a leak to the boost gauge. But when I had the dash apart it was clamped on there good. But who knows might have a needle leak or something. Would have to boost leak test the car with the dash up to see if it is leaking at the gauge. Sorry for the ramble in my original post.
Just for clarity, the Aeroforce ScanPro reads the manifold PSI from the PCM via the OBD-II connector, not the MAP sensor directly.
Also, lots of guys have used just the WGA to control boost since 2003 !
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post #5 of 6 (permalink) Old 05-24-2019, 05:15 AM
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Quote:
Originally Posted by Simon.Starkie View Post
Just for clarity, the Aeroforce ScanPro reads the manifold PSI from the PCM via the OBD-II connector, not the MAP sensor directly.
Also, lots of guys have used just the WGA to control boost since 2003 !
having a non-oem style turbo makes this a bit different though. When it is not internally gated, there is not adjustability of the boost pressure from the wastegate other than a boost controller or changing out the springs inside the wastegate.


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post #6 of 6 (permalink) Old 05-24-2019, 06:33 PM
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N2mb Boost by gear seems so much easier. Especially if externally gated

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