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boost overshoot going uphill

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Old Mar 18, 2009 | 07:45 AM
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Default boost overshoot going uphill

I'm getting boost overshoot when under high load, i.e. going up a hill. Is there any way to calm that down? I'm thinking removing the bottleneck in my exhaust might help...thoughts?
Old Mar 18, 2009 | 11:54 AM
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I can't imagine I'm the only person experiencing this. Bueller?
Old Mar 18, 2009 | 12:14 PM
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this is with Ebc?
Old Mar 18, 2009 | 12:37 PM
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Yup, EBC.

Basically, I hit rock solid 9-10 psi on a flat road, and a fairly solid 12 psi going uphill, or any other time there is excessive load on the engine.
Old Mar 18, 2009 | 01:29 PM
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There have been two other threads on this recently. Both determined that the 16G either doesn't like little exhausts and/or low boost pressure.

Your wastegate is probably experiencing too much backpressure from the exhaust to work efficiently.

If the larger exhaust doesn't fully eliminate your issue the wastegate opening is possibly too small to bleed off the exhaust efficiently. It can be ported and a larger flapper installed. Not likely that this will be a problem after you open up your exhaust system.

Someone else said that they had no problem with creep, but they had a lot higher boost setting and probably had other factors in their favor.
Old Mar 18, 2009 | 01:31 PM
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crush bends ftl
You need to update to the new MS ebc code for closed loop. Do you make less boost going downhill (less load)? It would seem to me that open loop bc is the problem.
Old Mar 18, 2009 | 01:34 PM
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Where are you getting your wg signal from?
Old Mar 18, 2009 | 01:39 PM
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No hills here in FL, sorry.
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Old Mar 18, 2009 | 01:45 PM
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Originally Posted by m2cupcar
crush bends ftl
You need to update to the new MS ebc code for closed loop. Do you make less boost going downhill (less load)? It would seem to me that open loop bc is the problem.

they come out with it yet?




ive hit a boost cut uphill once, i was in 4th and didnt feel like downshifting. the solution for me raising the boost cut :P
Old Mar 18, 2009 | 01:47 PM
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Originally Posted by levnubhin
No hills here in FL, sorry.
A hill is like a naturally occurring overpass with dirt filling underneath it. I saw one once as a kid.
Old Mar 18, 2009 | 01:55 PM
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Originally Posted by sixshooter
There have been two other threads on this recently. Both determined that the 16G either doesn't like little exhausts and/or low boost pressure.

Your wastegate is probably experiencing too much backpressure from the exhaust to work efficiently.

Someone else said that they had no problem with creep...
Hmm, not sure how I missed the other threads. I'll take a look around.
It's not creep per se, just hitting a higher boost and sticking there.

Originally Posted by m2cupcar
crush bends ftl
You need to update to the new MS ebc code for closed loop. Do you make less boost going downhill (less load)? It would seem to me that open loop bc is the problem.
Indeed, one crush bend (truthfully, it's a squeeze bend rather than a proper cruch bend ) ruins the party.

Originally Posted by Braineack
they come out with it yet?
^ I second the question. I'd heard rumblings about MS2 stuff, but nothing for MS1.


Originally Posted by Braineack
ive hit a boost cut uphill once, i was in 4th and didnt feel like downshifting. the solution for me raising the boost cut :P
This sounds like a plan, once I get a better tune up in that range.

Funny that this didn't happen with my old IC...
Old Mar 18, 2009 | 02:01 PM
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Originally Posted by sixshooter
Where are you getting your wg signal from?
right outside the compressor outlet
Old Mar 18, 2009 | 02:16 PM
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Originally Posted by Atlanta93LE
...Funny that this didn't happen with my old IC...
It was like having a crush bend on the other side of the turbo
You've disturbed the balance. Raise the boost limit and where will it end?
Old Mar 18, 2009 | 02:25 PM
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In another recent thread it was discussed that the hot side of the intercooler should never be the source for your wastegate signal or boost gauge lines. Disregard the factory outlet nipple. Use a source between the IC and the throttle body. Much more reliable signal. The hotside will give you strange behaviors.

I'll hunt for the posts.

EDIT: Found one. Pay particular attention to Professor Joe Perez's dissertations as the thread progresses. https://www.miataturbo.net/forum/t32479/

Last edited by sixshooter; Mar 18, 2009 at 02:40 PM.
Old Mar 18, 2009 | 02:44 PM
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Originally Posted by sixshooter
A hill is like a naturally occurring overpass with dirt filling underneath it. I saw one once as a kid.

You lie!
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Old Mar 18, 2009 | 03:32 PM
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Originally Posted by m2cupcar
You need to update to the new MS ebc code for closed loop.
DO TELL where the new code is for MS1!!!
Old Mar 18, 2009 | 03:43 PM
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Originally Posted by sixshooter
In another recent thread it was discussed that the hot side of the intercooler should never be the source for your wastegate signal or boost gauge lines. Disregard the factory outlet nipple. Use a source between the IC and the throttle body. Much more reliable signal. The hotside will give you strange behaviors.

I'll hunt for the posts.

EDIT: Found one. Pay particular attention to Professor Joe Perez's dissertations as the thread progresses. https://www.miataturbo.net/forum/t32479/
Thanks for the link. I'll read through that one again, although I recall it mostly having to do with boost drop-off.
Old Mar 18, 2009 | 03:53 PM
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Originally Posted by m2cupcar
You need to update to the new MS ebc code for closed loop.
WHAT!? They actually fixed it! I am getting so excited, where is this code!?!?!?
Old Mar 18, 2009 | 05:18 PM
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Whoa - sorry guys - I was just BS'ing. I do have some working closed loop code. Though it's over ten years old... and in my LINK.
Old Mar 19, 2009 | 06:34 AM
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Originally Posted by m2cupcar
Whoa - sorry guys - I was just BS'ing. I do have some working closed loop code. Though it's over ten years old... and in my LINK.
ohh your going to die.
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