The Official CTS-V Pic Thread
05-18-2016, 02:01 PM
#1361
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Looks like part of your tuning issues are coming from the vacuum leak you've got going on. I see you are still running a MAF but you're pulling fresh air for the PCV from the atmosphere and not post MAF. That fresh air needs to come from the intake tube after the MAF. That might help a little. Since your car is an 05 it didn't come with the nipple in the intake tube since the original TB had its own. 06-07 intake tubes (stock and aftermarket) had a nipple in the tube for fresh air. I had to add a fresh air port on my tube after I switched to the LS2 90mm TB on my LS6.
05-18-2016, 05:30 PM
#1362
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They do not have a PCV valve but they still have a PCV system. They way yours is set up you are pulling in air from the valley via the catch can. But where do you think that air is coming from? Its coming from the breather on the passengers side valve cover. That is unmetered air entering the engine and will cause all kind of tuning issues. IF you had an
SD tune this setup would be fine, but with the MAF still in place, any air that goes into the engine needs to be drawn through the MAF.
To correct your setup all you need to do is run the passengers valve cover to a nipple on the intake tube after the MAF. This way the air that is being pulled into the engine through the crankcase is metered. Obviously the car will need to be retuned after this since you've tuned the car with a vacuum leak.
SD tune this setup would be fine, but with the MAF still in place, any air that goes into the engine needs to be drawn through the MAF.
To correct your setup all you need to do is run the passengers valve cover to a nipple on the intake tube after the MAF. This way the air that is being pulled into the engine through the crankcase is metered. Obviously the car will need to be retuned after this since you've tuned the car with a vacuum leak.
Last edited by raven154; 05-18-2016 at 05:54 PM.
05-18-2016, 09:14 PM
#1363
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^^^ Exactly correct. Open breathers on a MAF car are a bad idea. I can't say that it's responsible for all of the tuning issues you've had, but it certainly isn't helping. The fact that a tuner didn't immediately identify that as an issue makes me wonder ...
05-18-2016, 11:17 PM
#1364
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You can see this red line that I added. Just route the hose from the valve cover to the intake tube. I would think about doing the swap with CaptSlow if he's willing or simply adding a nipple is easy and cheap as well.
05-19-2016, 11:37 AM
#1365
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Thanks for clarifying that, I understand what you are saying now. Never really put 2 and 2 together and realized it was pulling air through those breathers, but not sure where I expected it to be coming from, lol.
My remaining question then is, what about the breather on the drivers side valve cover? Do I need to do something with that also, or just leave the breather on there?
PM sent about swapping intake tubes...
My remaining question then is, what about the breather on the drivers side valve cover? Do I need to do something with that also, or just leave the breather on there?
PM sent about swapping intake tubes...
05-19-2016, 12:36 PM
#1366
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Nintastio, first off great looking car and one hell of a motor!
You will never have stock like drivability with that big of a cam. It will always buck or surge a little creeping along at low rpm. I had a 251/259 .650/.650 112 cam in my goat and I will probably never go that big again because of the drivability. Just keep it around 2k rpm and you will be smooth. Just the life of owning a big cam
EDIT: sounds like that was a third gear pull on the dyno as well. From my experience, you do pulls in 4th
You will never have stock like drivability with that big of a cam. It will always buck or surge a little creeping along at low rpm. I had a 251/259 .650/.650 112 cam in my goat and I will probably never go that big again because of the drivability. Just keep it around 2k rpm and you will be smooth. Just the life of owning a big cam
EDIT: sounds like that was a third gear pull on the dyno as well. From my experience, you do pulls in 4th
The dyno pulls were all done in 4th gear since it is a perfect 1:1 ratio.
05-19-2016, 01:36 PM
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I didn't notice the second breather but I see it hiding back there now. Yes that needs to be capped off as well. Or tied to the other line going to the intake tube. Just depends on how you want to do it.
05-26-2016, 09:22 AM
#1369
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Nothing yet, I'm waiting to see about swapping intake tubes with another member here.
Then I also want to put a catch can between the intake tube and the lines I currently have breathers on. I don't want the inside of my intake covered in oil, but I'm a bit tight on cash right now to get it done very quickly.
Then I also want to put a catch can between the intake tube and the lines I currently have breathers on. I don't want the inside of my intake covered in oil, but I'm a bit tight on cash right now to get it done very quickly.
05-26-2016, 10:54 AM
#1370
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Just got word from Capt Slow that he shipped out the intake tube so I should have that here in a few days.
I was planning to run both the valve cover breathers into a catch can, then from catch can to the intake. Three port catch cans aren't very popular, so should I just bite the bullet and over pay for a 3 port? Or just T the valve cover breathers together before the catch can and get a normal two port catch can? Sorry if that's a stupid question but just want to make sure I've got this correct since I thought I already did and was wrong.
I was planning to run both the valve cover breathers into a catch can, then from catch can to the intake. Three port catch cans aren't very popular, so should I just bite the bullet and over pay for a 3 port? Or just T the valve cover breathers together before the catch can and get a normal two port catch can? Sorry if that's a stupid question but just want to make sure I've got this correct since I thought I already did and was wrong.
05-26-2016, 11:34 AM
#1371
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You only need a catch can between the vacuum port and the valley. The hose going into the intake tube from the valve covers is there only for fresh air so you wouldn't be pulling any oil in from those lines. When the engine is running its sucking air out of the intake tube into the valve covers. From there it goes through the crank case and out of the valley via the suction hose from the intake. On its way it's evacuating all the oil vapors from the crank case. That's why the catch can goes between the valley and the vacuum port.
05-26-2016, 11:50 AM
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You only need a catch can between the vacuum port and the valley. The hose going into the intake tube from the valve covers is there only for fresh air so you wouldn't be pulling any oil in from those lines. When the engine is running its sucking air out of the intake tube into the valve covers. From there it goes through the crank case and out of the valley via the suction hose from the intake. On its way it's evacuating all the oil vapors from the crank case. That's why the catch can goes between the valley and the vacuum port.
05-26-2016, 01:17 PM
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I believe it's only leaking oil because of the current way it's setup. Once setup correctly, oil wouldn't have a chance to come up those because that is where the fresh air is coming in at.
05-27-2016, 10:29 AM
#1375
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Okay, awesome. I think I finally understand the system as a whole now. Thanks again for helping a noob out! Going to take it back to the tuner after I get everything switched around and hope he has an easier time getting everything dialed in now.
05-31-2016, 01:42 PM
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06-01-2016, 08:44 AM
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06-01-2016, 10:17 AM
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06-06-2016, 04:00 PM
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