drich2905

hope you guys can steer me in the right direction: I have an 08 vert
with M2W and both flaps stay open all the time. Here is what I have done so far-

disconnected the M2W and put both 10A fuses back in- flaps still open with engine running

Checked the flaps and moved them manually- vacuum lines are in place on the mufflers- everything moves freely

Pulled the exhaust fuse and flaps stayed open all the time with engine running.

Check the solenoid in the rear bumper- all lines and electrical connections
look normal.

I don't have a vacuum tester but I pulled off the line going to the front of the car and there is definite suction on that line with the engine running. So I replaced that line and pulled off the line going to the mufflers and there was no suction coming out of the outlet of the solenoid.

Does that mean the solenoid is bad?

I wanted a little advice before I ordered a part-

BTW- I have done a search and looked at a number of post about failed NPP issues related to mine.

thanks

AORoads

sounds like it to me, unless there is some obstruction in the line somewhere. the vacuum keeps the flaps closed. I don't know how or if the m2w caused anything to fail (I tend to doubt it). maybe it's just the solenoid's time to fail, altho I don't know too many that have failed at all, for any reason.

Greg00Coupe

Can't help ya........ got the NPP on my GS too.....

It's not the M2W you've proven that already. It's a problem in the system itself.

This is why I'll never have it again..........something else to go wrong.........so much more complicated then a simple Corsa or aftermarket system.

red2012

Ah that's hog wash. . The probability of that part breaking is no more than any other part and if that's the case don't even order the car with a motor just push it as that might break also. Ridiculous reasoning.

bosco 08

Everything I did is posted here and is correct to the best of my knowledge.

http://forums.corvetteforum.com/c6-t...pp-issues.html



The solenoid was bench tested and it worked fine. In the end I think heat caused the old one to fail because the exhaust would work as designed until you drove it. I would imagine it gets warm back there being as the mufflers are right below it. The solenoid may have had a windings issue that only caused it to fail when hot. The solenoid is NC, it opens when voltage is applied so when the solenoid fails it closes and the flaps stay open.
Good luck.


btw way if you find out it's not the solenoid and it's the exhaust control module mounted above the right rear wheel house in the cargo area I have one I will sell cheap.

drich2905

thanks guys-

I did read another search thread where someone suggested check the wiring harness going to the solenoid while the car is running to make sure it is getting power.

I did that and it registered about 13.69V.

So, it seems the solenoid is getting power, good vacuum is getting to the solenoid, but no vacuum is coming out.

If it looks like a duck, and quacks like a duck, well....................

I have contacted Gene at GMPartshouse about ordering a solenoid.

It seems all the threads I read had very few photos. I will try to get some and post it for then next guy/gal who comes along and wants to replace one of these doodads.

Hameister

I ordered a car with a radio a few years ago. It stopped working after only 6 months, I'll never buy a car with a radio again.

LMB-Z

I have B & B Fusions on my Z06. When I first got it, the valves would not work either. After several hours, finally figured out the solenoid was bad. I think it was $35. Works fine now. Hope you get it figured out.

Greg00Coupe

Oh excuse me...... you're right.... Why would I order a Corsa with 10 more HP with sound cancelling technology....i.e. no parts, vacuum, or electronics....... when I can give GM the money and get a free constant drone????

Koolaid is free today......

There a no alternatives to an engine but many to an exhaust. What a foolish comparison.

red2012

You ever hear of Mild To Wild? No constant drone on my car.

bosco 08

The solenoid is appox. $60.00 with a discount from my local dealer.

The 90 degree rubber elbows (2) that connect the solenoid to the plastic vacuum lines are very hard to remove I ended up tearing one. There is little room to work and you can't get any leverage to turn or pull them. Worse case is you may need a small section of vacuum line to replace a torn elbow just make sure to loop it so there are no kinks. I was lucky in that the dealer tried to order them and the only way he found was ordering the section that goes to the vacuum ball reservoir. Maybe Grainger will have them I don't know.
Good luck.

Pat Bentley

Brutal but funny.

traderfjp

NPP is a must have for me. I love being able to control the exhaust note.

drich2905

Hey Guys,

I am having trouble finding a source for the new solenoid. Seems that GM is back ordered with no ETA.

If anyone has a source please let me know.

z51vett

My son inlaw had those noise all the time with npp on my z06 I have quiet and loud. Loud tooling around and quiet on the interstates on trips.
z51vett
Doug

z51vett

Do you have vacuum up to solenoid? If so it is the solenoid pull line feel for it.
z51vett
Doug

drich2905

just in case this will help someone one day here are some photos of
the solenoid

Remember to take out both passenger tail lights to get access to the
part.

the first photo is looking into a tail light hole. The cover is over the solenoid. The fastener on the left can stay attached. The cover appears to be a thick fiber material (very bendable). On the right of the cover is a black push pin. I could not get the pin to come out but pulled on the cover and it came off the pin.



when you flip the cover from right to left you will see the solenoid. I used a small flat head screwdriver and a little elbow grease to get the rubber attachments off the black attachments. Very easy. just be careful with the screwdriver and don't tear the rubber attachments.

Jon@bbexhaust

Thought I'd throw in my $.02. I see the letters NPP and get all excited

We have our Fusion system, which is much like the NPP, using butterfly valves to direct exhaust flow through loud or quiet passages. It can be put in place of the factory NPP mufflers, and is actuated by the signal from the factory NPP. It can also be controlled by an interior mounted switch. We also offer a retrofit kit that to install the system on non-NPP equipped vehicles. The valves are controlled by an interior mounted switch with this set up. On the loud side it sounds very aggressive - like our Bullet exhaust. On the quiet side the sound is more tame and doesn't drone. Basically, the same sound and no drone as the PRT. Compared to stock it makes an additional 10-12 hp on the quiet side, and 18-22 on the loud side. More info: http://www.bbexhaust.com/car/corvette/c6fusion/

drich2905

just wanted to finalize my older thread. I just got the in solenoid from Gene Culley at GMParthouse and it solved the problem.

At least for me it was pretty easy to determine that the solenoid was the problem. I pulled off the line going toward the front of the car and noted a vacuum on my finger but there was no vacuum coming out of the exit for the hose that goes to the actuator in the mufflers. Since it takes vacuum to close the flaps and I was getting vacuum to the solenoid I felt it best to replace the solenoid.

With some detective work from Gene I did discover that a previously reported part number on the forum was not what I needed.

The part number for just the solenoid is # 25794610.
If you want the solenoid plus the vacuum lines order #25794609.

I didn't need the vacuum lines and after installing the new solenoid the NPP works perfectly.



this is the solenoid only

joeflylow

t first my exhaust was open intermittent, then open all the time. I replaced mine today. The coil resistance (of the solenoid) measured 287 Ohms; the new one measured 22 Ohms and pulled about half an amp of current. Oddly, when I connected each of them to a dc power supply, I did not hear any noise.