Rough idle with forced induction

nomodsjk

I guess there is some solace in the fact that galeforce is having the same issue. Not to be taken negatively. If he's having this issue with his extensive knowledge and experience with modifying 370s then I don't feel so bad

Mitco39

I guess ill just stop contributing to this topic. I will get to the bottom of this idle, I have a bunch of theories but I am limited by what I have to work with what tables Uprev gives their "non pro tuners".


Jason, how much you pay this guy? lol.

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2007 Chevy Duramax - EFILive Tuned By Me
2010 40th W/ Nav - Boosted Performance - UpRev Tuned By Me
The Mrs. Ride -2012 335XI N55 BMW - Cobb Tuned By Me, Built by her
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jwick

No Mitch please don't. Some of us know the truth

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jwick

And

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'10 G37T 6MT Graphite/Graphite - BP - G37T Build

Mitco39

lol, it just rubbed me the wrong way. Hopefully ill get some time to play with the car this weekend. I would like to wait for the boost tubes from Sasha before tweaking with the tune. I was thinking of pulling the bottom of the tubes off the intercooler and just letting it suck air like it otherwise would and see if its the restriction causing these issues.

Its clear to everyone that its bouncing. Which means that the natural frequency of the O2s to switch from rich to lean is getting close to to natural frequency of the intake system. I suspect thats whats happening. That would cause the hunt, and if we tap back in the crankcase pressure lines with a PCV valve (to protect the bottom end under boost) this would allow the system to operate at a vacuum and change the natural frequency of the system.

One way to find out, lol it just involves tapping into my boost tubes, but hey if im getting new ones anyways I might as well give it a shot.

__________________
2007 Chevy Duramax - EFILive Tuned By Me
2010 40th W/ Nav - Boosted Performance - UpRev Tuned By Me
The Mrs. Ride -2012 335XI N55 BMW - Cobb Tuned By Me, Built by her
My Build --> http://www.the370z.com/members-370z-...39s-build.html

jwick

I hear you! Other than us providing alternate data points you are the driver of what's going on in the progress of a solution My man!

Question - Can you route the PCV back into the intake tubes? The only reason I ask this is because the GTM TT kit has them routed in the air filter tubes pre-turbo. From the experience I have with those kits, they aren't having the issues we are.

That being said, I don't know how we do that since the filter is clamped directly to the compressor inlet.

I'm definitely down for a solution. I'd happily tap my intake piping for the PCV system if it'll take care of the hiccup.

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'10 G37T 6MT Graphite/Graphite - BP - G37T Build

Mitco39

Just looking at the service manual now... It has 2 crankcase ventilation systems working together. Im not sure if my idea of putting it into the intake would be sufficient. Right now I bet the car is drawing unmetered air in through the lets call it primary ventilation circuit through the intake manifold. Now with the secondary ventilation circuit to atmosphere one could assume that its sucking air in through this secondary vent circuit into the crankcase then out through the PCV valve and into the intake manifold. Ill find a picture and post it up explaining that.

This would allow unmetered air to make its way into the engine, although when a engine idling it is supposed to be in closed loop which shouldn't affect its operation to much, however if the vacuum pressure in the manifold is changing slightly it would change the combustion process enough that could cause the hunt as it continually tries to stabilize itself.

I like thinking problems, lol.

__________________
2007 Chevy Duramax - EFILive Tuned By Me
2010 40th W/ Nav - Boosted Performance - UpRev Tuned By Me
The Mrs. Ride -2012 335XI N55 BMW - Cobb Tuned By Me, Built by her
My Build --> http://www.the370z.com/members-370z-...39s-build.html

09 Nismo#400

Mitco39, I am guessing your thinking of adding something like this: mpx_check_valve then route the PCV back into the intakes, kind of like the OEM intakes do?

jwick

My engineer brain is going to have to see a visual that I can then link back to my familiarity of the engine bay to understand exactly what you just said. Caught the meaning but not the actuallys

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jwick

That's my working understanding too. You need the check since we would be tying in where you can see positive pressure. Treadstone makes something similar.

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nomodsjk

[QUOTE=Mitco39;2939877]lol, it just rubbed me the wrong way. Hopefully ill get some time to play with the car this weekend. I would like to wait for the boost tubes from Sasha before tweaking with the tune. I was thinking of pulling the bottom of the tubes off the intercooler and just letting it suck air like it otherwise would and see if its the restriction causing these issues.

Its clear to everyone that its bouncing. Which means that the natural frequency of the O2s to switch from rich to lean is getting close to to natural frequency of the intake system. I suspect thats whats happening. That would cause the hunt, and if we tap back in the crankcase pressure lines with a PCV valve (to protect the bottom end under boost) this would allow the system to operate at a vacuum and change the natural frequency of the system.

One way to find out, lol it just involves tapping into my boost tubes, but hey if im getting new ones anyways I might as well give it a shot.[/QUOTfE]


Apparently I missed something. I'm guessing I rubbed you the wrong way. I mentioned Jason in my post because he was the op of this particular thread even though he just quoted you. Didn't mean to belittle your efforts or rub you in any way..

Mitco39

Upon looking at it more closely I have a check I am going to try. I am just going to pull off what I refer to as the primary circuit and vent it to atm. That will stop any chance of this sort of thing happening. Right now I believe all the kits keep this circuit so that they are not blowing out oily emissions all down the car.

What I am referring to as the primary circuit is the purple highlight, green is the secondary with the filters on it currently.

__________________
2007 Chevy Duramax - EFILive Tuned By Me
2010 40th W/ Nav - Boosted Performance - UpRev Tuned By Me
The Mrs. Ride -2012 335XI N55 BMW - Cobb Tuned By Me, Built by her
My Build --> http://www.the370z.com/members-370z-...39s-build.html

Mitco39

Thats what I was thinking of at first yes. And might still have to try something like that. Or might just delete the PVC system all together, although then its a question of what to do with the oily mess it leaves.

__________________
2007 Chevy Duramax - EFILive Tuned By Me
2010 40th W/ Nav - Boosted Performance - UpRev Tuned By Me
The Mrs. Ride -2012 335XI N55 BMW - Cobb Tuned By Me, Built by her
My Build --> http://www.the370z.com/members-370z-...39s-build.html

Mitco39

Your an engineer as well? Awesome. I am a Mechanical Engineer working on structural design for drilling rigs. Although the automotive field is where I want to be some day.

__________________
2007 Chevy Duramax - EFILive Tuned By Me
2010 40th W/ Nav - Boosted Performance - UpRev Tuned By Me
The Mrs. Ride -2012 335XI N55 BMW - Cobb Tuned By Me, Built by her
My Build --> http://www.the370z.com/members-370z-...39s-build.html

jwick

See the pic tells a thousand words. So the primary is the two that tie into the IM right where we tapped for the BOV feed. That must not have as much of an effect on the system as the secondary because all the kits I know of keep that setup.

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