Hi all,

So I have an 09 Z06 with HCI making right around 580hp/500torque to the wheels. I love the car to death, but my neighbors hate me. My NPP valves stopped working and starting my car in the garage shakes the whole damn townhouse complex. My neighbors told me their windows shake..... A few car guys around me love it, but I know the non car people hate me to death.

So far, I checked the fuse and I replaced the solenoid. Tonight, I got under the car to check the vacuum canister and the hard line next to the mufflers. I couldn't find anything wrong. I used a phone borescope attachment to check the vacuum line connection to the MSD intake manifold and it seems fine with no tears or anything that I can see. I also attached a syringe and drew vacuum on both NPP attachments and saw the valves close, so the NPP diaphragms are intact.

After doing some research, I did see some people said that the vacuum solenoid (the one in the passenger side rear bumper area) should be totally closed when there's no power going to it. As in, if you try to blow into any hole, you shouldn't be able to unless you apply 12 volts to it. Well, both the old and the brand new one let me blow through one of the two vacuum line attachments. I'd like to get a confirmation that the solenoid should be 100% blowproof (wow that sounds wrong)... I already spent $50 on a piece of plastic so I'd rather not spend another $50 to see if I indeed got a defective one from GM.

I'd truly appreciate any help I can get because I'm using a piece of wood to jam the NPP actuators shut while leaving the neighborhood and entering it

 

Just the port to the intake manifold should be switched open by 12 volts to it.
The port side to the mufflers stays open, so vacuum can bleed out when the switch is closed by the NPP controller to allow the vacuum to the gate valves to bleed out and open the gates back up when power is cut.

As for possible problems start the motor, and check the line to the manifold to see what kind of vacuum you have.

Hence wild enough cam, and your intake manifold pressure is going to be low as hell and may not be enough vacuum to close the gates.

Hell, another quick test if you want to weed out problem with the NPP and even intake vacuum being high enough, install a nipple to both vacuum lines to connect the togehter to get the vacuum through the system, and check the voltage on the OEM silenoid connector pins to make sure you don't have either a 12 voltage problem from the NPP controller, or a bad ground problem on the G302 connection point as well


Ground G302 is #7


Npp fuse is the bottom right 10 map fuse in the BCM.


And NPP controller is in the back passenger chubby on the right hand side.




Lastly, if you have a mild to wild controller in the system, pull its add a fuse connector from the fuse box and install a 10amp fuse back in the fuse box. The M2W controller first cam out with a 6 amp relay (RM01), then it was changed to a 15 amp relay on the RM02 controller. Hence oem NPP system may be fine, but M2W relay melted and why it not getting power to the OEM NPP controller when you are switching it with the fobs to quiet mode. If you find that its the M2W that is the problem, here you go on a replacement.

 

Thank you for such a detailed response. I hope to have some time today to dig some more into this. I did have a M2W switch but I removed it and replaced with factory fuses when it stopped working. The system was working ok for about 5 days after the MSD manifold went on. After that, it just stayed open. I was thinking the manifold vacuum line either slipped off or broke, but it doesn't seem to be the case. I may have to pull the manifold to double check I guess,.

I'm trying to go from the easiest to the hardest solution lol.

 

Just bypass the solenoid, vacuum wise. Run the vacuum line direct from intake manifold to the canisters. Valves will still open under full throttle and will stay closed under light throttle (high vacuum), assuming that your camshaft isn’t so radical that it doesn’t make decent vacuum

 

Yes, and no, Hence with reserve vacuum bladder (25) still in play, it's going to hold the gates closed for a few seconds when he does go to full throttle.


As for vacuum checking the system, best way is to nipple through the solenoid to connect the lines there, then put a vaccum pump on the intake line once it's pulled from the intake vavle to check for leaks. The PITA is getting to the intake line to pull it off the port to begin with.

 

I've found some great threads via searching for keywords in google. Threads like these:

https://www.corvetteforum.com/forums...-fixed-it.html

https://www.corvetteforum.com/forums...placement.html

My vacuum tester comes in the mail today. Hopefully I fix the issue once and for all this weekend.

 

Alright so I checked the vacuum lines to the mufflers from solenoid, the actuators closed with no issue.

I took the front line off of the solenoid and vacuum held there no issue. So there's no vac leak from solenoid to the firewall connector either.

I disconnected the hard line at the firewall and tested there to double check, no vacuum leak there. This to me proves that there's no vacuum leak from the car to the muffler actuators.

I then took the elbow off and tested the line coming off of the manifold. There was no vacuum leak! This left me speechless because wtf... How is the manifold holding vacuum when the car is off?!

I have the MSD intake manifold and this issue started happening a few days after the install. I'm wondering if the vacuum reservoir canister had enough vacuum to hold the actuators shut for those days.

With the vacuum pump still hooked up to the manifold line, I started the car and the needle didn't move. So, I'm getting no vacuum off of the manifold when it's on, but if I pump the vacuum, it holds fine when the car is off.

I forgot to try pumping it while the car was on to see if would build vacuum, but I'm pretty certain the manifold hole isn't drilled out for the exhaust vacuum line.

Anyone know if the MSD comes predrilled for that port?

Thanks again to everyone offering ideas. This is getting insanely frustrating.

Now off to drink some beers to soothe the cut up hands from the tail light holes.

 

Think you answered your own question on the intake port, and its still sealed for none NPP apps.

So comes the Joy of pulling the intake off, so you can drill the port to open it's channel.

 

Yea it's sort of like talking through a problem out loud and you reach the answer yourself.

I'll call the shop that did the install to see if they're willing to do it for me. Otherwise I guess I'll just do it myself.

I can't see the requirement to drill that port out anywhere though. I know the map sensor location had to be drilled but why would they seal up that port?

 

That port is open just like the brake booster port is on a brand new MSD

 

Damn. Well I'm back to square 1 then. I'm still unclear how the vacuum line running to the manifold can hold a vacuum. I disconnected it from the 1 way valve too. I guess I'll do more testing.

Thanks for confirming that it's open from the factory.

 

The line between the manifold and the one way valve? Right before the quick fitting onto the hardline? That's weird no idea.

 

Yup, that's the line. I took the elbow off so that I had a direct link with the manifold with my vac tester. When I pump the tester with car off, it holds vacuum fine. I left it attached and turned the car on, no reading at all. The needle stayed at 0. Tonight I'll try pumping it with the car running.

 

Is it BOTH valves or just one side? Have you eliminated the possibility that its not a mechanical problem? You should be able to actuate the valve's by pushing them closed manually...They should spring/flop back when released. If its sticking at all then you may have a mechanical failure. Of course both valves going bad at the same time is unlikely.

I would at least have someone pull the fuze and reinstall it while you watch the valves in the back to verify/confirm its both valves that are failing.

I would also see if you can eliminate the possibility of the diaphragm in the valve vacuum canister is not punctured or leaking. You can do that simply by putting a clean vacuum line on the valve and then sucking on the end till the valve closes (may want to elicit an ex GF to do the deed for you... or just use that vacuum tester and pump it till the valve closes... ) .. if it does not close... then that could be your problem.

Good Luck.

SPEED SAFE, NICK

 

Just to update this thread, the issue was a mold issue on the nipple. There was a tiny overmold flap blocking the airflow. Took it apart and drilled the hole out.

This explains how the car was holding perfect vacuum when I checked the hose going to the manifold. Hence my initial question of if it's drilled out or not. It's supposed to be, but I guess MSD molds aren't QCd that well.

This was before selling that manifold to inspect what was going on. I bought a MAMO ported one as a replacement.