Rough idle with forced induction

jwick · 08-22-2014, 01:31 PM

Quote:

Originally Posted by 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.

That's pretty funny. I'm structural but working as a facilities engineer on offshore platforms. Small world

I think we each have each others jobs

Mitco39 · 08-22-2014, 01:41 PM

Quote:

Originally Posted by 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.

yes they tie in there and under idle the manifold is under a vacuum that sucks in crankcase vapors. Now before the kit the crankcase would be filled with air from the intake between the maf and the throttle body. But now this air is just entering the system through those two fiilters and straight into the intake at idle.

jwick · 08-22-2014, 01:55 PM

Quote:

Originally Posted by Mitco39

yes they tie in there and under idle the manifold is under a vacuum that sucks in crankcase vapors. Now before the kit the crankcase would be filled with air from the intake between the maf and the throttle body. But now this air is just entering the system through those two fiilters and straight into the intake at idle.

Just throwing ideas out. Partially for my understanding and partially to see if any trigger some light bulb in your mind that leads us to a solution. I could be completely off but stick with me. So NA it's pulling metered air in from the intake (post-MAF). I would guess the ECU is expecting a certain amount of air to be removed from what it's metering, where in reality (vented) the crankcase is pulling in as much unmetered air as it wants. There is no adjustment for that air not being removed and when you come off throttle it hiccups because it's getting more air than it expects leading to the lean condition. Which is what we see happening.

But let me throw an additional monkey wrench. The GTM kit ties that secondary in pre-MAF, so it has to be something different or in addition to what I stated above or there is something in the tuning that can correct for that.

Mitco39 · 08-22-2014, 02:11 PM

Quote:

Originally Posted by jwick

Just throwing ideas out. Partially for my understanding and partially to see if any trigger some light bulb in your mind that leads us to a solution. I could be completely off but stick with me. So NA it's pulling metered air in from the intake (post-MAF). I would guess the ECU is expecting a certain amount of air to be removed from what it's metering, where in reality (vented) the crankcase is pulling in as much unmetered air as it wants. There is no adjustment for that air not being removed and when you come off throttle it hiccups because it's getting more air than it expects leading to the lean condition. Which is what we see happening.

But let me throw an additional monkey wrench. The GTM kit ties that secondary in pre-MAF, so it has to be something different or in addition to what I stated above or there is something in the tuning that can correct for that.

You could be right, as the car switches from open loop to close loop it could cause a hiccup until it stabilizes itself. Easy way to try and see if this is causing it is to pull both lines and plug the ports in the intake manifold and idle the car and see what happens. You could just vicegrip the lines to and let the secondary system do all the venting. I am going to try that this weekend and see what the car does.

Is that secondary drawn in pre-turbo? It could be that there is enough vac pre turbo to keep the air being drawn through that system to minimum. But your right the same principle applies in this case as well. Its a head scratcher for sure. Ill try and get some time tonight with the car.

jwick · 08-22-2014, 02:21 PM

Quote:

Originally Posted by Mitco39

You could be right, as the car switches from open loop to close loop it could cause a hiccup until it stabilizes itself. Easy way to try and see if this is causing it is to pull both lines and plug the ports in the intake manifold and idle the car and see what happens. You could just vicegrip the lines to and let the secondary system do all the venting. I am going to try that this weekend and see what the car does.

Is that secondary drawn in pre-turbo? It could be that there is enough vac pre turbo to keep the air being drawn through that system to minimum. But your right the same principle applies in this case as well. Its a head scratcher for sure. Ill try and get some time tonight with the car.

As I understand it, yes pre-turbo. My buddy has a GTM TT and he tells me its routed in the intake filter tube before the turbo. I'm almost positive he's correct too because you can clearly see the upper pipe (IC) and that's not where it's tied in.

GaleForce · 08-22-2014, 04:34 PM

Quote:

Originally Posted by 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

I just started the thread, and put the question out there. Mitch is the brains. I don't have a clue when it comes to tuning. I'm learning from everything Mitch, Phunk, Jwick, et al, are saying in the other thread..

Quote:

Originally Posted by 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.

Don't stop Mitch, you are an incredible resource! I'm learning so much reading your posts.

Quote:

Originally Posted by jwick

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

GaleForce · 08-22-2014, 04:45 PM

Quote:

Originally Posted by 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.

And I'm a Red Seal C&M Electrician who programs PLC, and robots, device net etc,etc, I also work with Engineers, and we are in the Automotive industry. Mitch, you have waaaaaay too much personality to be an Engineer in the automotive field, you're going to have to tone it down a bit.

Mitco39 · 08-22-2014, 04:59 PM

Quote:

Originally Posted by GaleForce

And I'm a Red Seal C&M Electrician who programs PLC, and robots, device net etc,etc, I also work with Engineers, and we are in the Automotive industry. Mitch, you have waaaaaay too much personality to be an Engineer in the automotive field, you're going to have to tone it down a bit.

I appreciate the kind words.

I hope to one day work for myself in the automotive field. Well I technically kinda do currently but I want it to become a full time setup. While I will admit to absolutely not being able to do anything to change the body of the car like yourself. I do usually grab hold of things a few at a time to see what can be improved and why it hasn't already been done.

Z1 is one of those shops who put the effort in to be new and explore ways to improve over what the factory has given us. Shops like them are few and far between and you will usually find them on forums such as this. Thats the sort of thing Id love to do, not so much OEM automotive stuff.

Thats awesome that you deal with PLCs and the like. I wish I paid more attention and took more courses dealing with coding and the processes used to deal with flashing and programming. It would have helped me out alot now when I find myself browsing forums to get the information.

One day at a time though, until then Ill toy around on here with this car.

nomodsjk · 08-22-2014, 05:03 PM

Again I made NO reference to who was trying to solve the problem just that someone else had the same problem, someone with more experience than me. No reason to get worked up over something that wasn't said.

Mitco39 · 08-22-2014, 06:10 PM

Quote:

Originally Posted by nomodsjk

Again I made NO reference to who was trying to solve the problem just that someone else had the same problem, someone with more experience than me. No reason to get worked up over something that wasn't said.

Its all good. No worries here.

jwick · 08-22-2014, 06:46 PM

Quote:

Originally Posted by Mitco39

Its all good. No worries here.

Ran a couple logs when I got home. Do we have a way transfer/upload them?

GaleForce · 08-22-2014, 07:08 PM

Quote:

Originally Posted by jwick

Ran a couple logs when I got home. Do we have a way transfer/upload them?

Dropbox?

GaleForce · 08-22-2014, 07:10 PM

Quote:

Originally Posted by nomodsjk

Again I made NO reference to who was trying to solve the problem just that someone else had the same problem, someone with more experience than me. No reason to get worked up over something that wasn't said.

It's all good. Just a bit of ball busting on the interwebz.

jwick · 08-22-2014, 07:40 PM

Quote:

Originally Posted by GaleForce

Dropbox?

Anybody got one?

Mitco39 · 08-22-2014, 11:30 PM

Dropbox or google drive works great.

08-22-2014, 11:30 PM	#90 (permalink)
Mitco39 A True Z Fanatic Join Date: Aug 2012 Location: Edmonton Alberta Canada Posts: 2,089 Drives: 40th 370z Rep Power: 131	Dropbox or google drive works great. __________________ 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

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08-22-2014, 05:03 PM	#84 (permalink)
nomodsjk Premium Member Join Date: Apr 2014 Location: martinsburg wv Posts: 2,073 Drives: 2011 370z MB/7at Rep Power: 19961	Again I made NO reference to who was trying to solve the problem just that someone else had the same problem, someone with more experience than me. No reason to get worked up over something that wasn't said.