BEZ06

Excellent!!

Glad you finally got it figured out.

Bob

bosco 08

It's easy to check the vacuum lines just hook-up a Mity-Vac at the engine connection if it holds vacuum with the engine off then you are good up to the solenoid. You can also use positive pressure to find a leak if needed.
I had the BCM checked by a local shop and it was functioning properly so with no leaks and a functioning computer it moved the focus back to the solenoid. I said earlier that I checked the solenoid on the bench and it was good when in fact it was sticking closed.
Anyway it's all good now and I learned a lot so it wasn't a complete waste of time.

Likecars

#5 Exhaust Tailpipe Flow Control Valve Solenoid. Picked one up at my local Chevy dealer part #325794609 $94.48 list they sold it to me for $67.31

This is the one behind the right taillight mentioned earlier in the post, did you need to remove both to work with it? Thanks

bosco 08

That's the one.
Yes on the both tail lights.

Flying24

Good info,
I need to start troubleshooting my problem. I have a 2008 Billy Boat NPP which I installed several years ago. Last week I was at Sebring with the NCM HPDE, and when I got on the road to head home which is more then 900 miles. My exhaust was droning like a mad man, and I have my wife as a passenger, and not to mention my brakes noise. So I first switched out the fuses and checked my foot switch, which I have to open the exhaust values. Then I disconnected it and put it back to stock, exhausts values never move from full open. I was pushing my car really hard, just in the 3 afternoon secession. I went through a entire tank of fuel. I could tell by my exhaust tips that they were quite hot, so I'm leaning towards a melted vacuum line. I just need to find sometime this weekend look where the pipes go over the axles.

69 L46 4 Speed

It does sound like a vacuum leak. Fortunately the ECM compensated for some of the lean condition by dumping more fuel in the mix. Hope you can find the problem.

Flying24

So a vacuum leak in the NPP system itself would have the ECM increase fuel mixture? That's pretty sensitive, considering the sole reason is to actuate the the exhaust values. I'm not saying your wrong, but that would explain my fuel usage. But my fuel consumption was pretty steady for the most part during the 2 days. Except for the last afternoon only because I was WOT as much as possible. The inside of my exhaust tips weren't solid black, but were a dirty white grey look as if I may be baking my CATS. At least that's what I thought. I just need to get it up on my lift. Today I'm off to get a crown, tomorrow I'm helping a friend who is going through cancer treatments. But I'm free this weekend, Thanks for you input

janoz06

My symptoms started as if my NPP actuators were sticking.
They would open when they were supposed to,however they would stay on(in loud mode) until I shut the car off.
Then they would be fine(stay closed)until I went past 3500 RPM.
I have an 08 Z06 and it ended being the Exhaust Intake manifold vacuum solenoid part No. 25794609.

Thanks all.

95BLKVette

I know it's 4 years later but I re-read your posts and you had tested the solenoid valve and you thought it was ok, so how was it defective?