[ZR1] OEM Exhaust Flaps Question
01-17-2011, 01:57 AM
#1
Melting Slicks
Thread Starter
OEM Exhaust Flaps Question
My car is still factory with no exhaust mod yet. When do the flaps open? Are they RPM and or throttle dependant as I'm guessing they open anywhere from 3000RPM to 3800RPM is that correct? Seems this way when I drive. How is this set up in the PCM?. Greg
01-17-2011, 06:24 AM
#2
From my experience, If giving it very light throttle, (a bit less than 10%) but still gaining speed, the flaps will not open even if you pass the RPM point where they usually open. Add a tad more throttle though, and the flaps appear to open right at 3100 - 3200 rpm. You can also experience the flaps closing when maintaining a higher RPM but backing off on the throttle sufficiently enough to hear the flaps close, as well as hear them open again when applying more throtltle. It's pretty noticeable, and kind of interesting. Congrats on your ride!
- Bryan
01-17-2011, 01:27 PM
#3
Race Director
The only definitive explanation of the dual mode exhaust I have is from my 2006 Service Manual for my '06 Z06.
You can see below that the Z06 (and I think the NPP option for the LS3 works exactly the same) requires RPM and at least 25% throttle for the valves to open. Also, when you let off the accelerator the valves stay open for about 2 seconds so they won't close when the RPM drops during shifts.
My experience with my 2009 ZR1 is that the valves work exactly the same (require both RPM and throttle, probably that same 25%), but it doesn't matter whether you're in Normal or Comp mode - if you've got enough throttle, the valves open at 3,000 RPM in either mode on the ZR1.
Here's the info from the 2006 manual:
Hope that info helps!!!
Bob
You can see below that the Z06 (and I think the NPP option for the LS3 works exactly the same) requires RPM and at least 25% throttle for the valves to open. Also, when you let off the accelerator the valves stay open for about 2 seconds so they won't close when the RPM drops during shifts.
My experience with my 2009 ZR1 is that the valves work exactly the same (require both RPM and throttle, probably that same 25%), but it doesn't matter whether you're in Normal or Comp mode - if you've got enough throttle, the valves open at 3,000 RPM in either mode on the ZR1.
Here's the info from the 2006 manual:
Exhaust Tail Pipe Flow Control System Description and Operation
The Exhaust Flow Control (EFC) System enhances engine performance. The system has 2 modes of operation:
• Normal
• Competition
Normal Mode
When the vehicle is stationary with the engine running the exhaust flow control module (EFCM) commands the vacuum solenoid On, which supplies engine vacuum to both exhaust flow control valves. This causes the valves to close, diverting exhaust flow through a baffled path inside the mufflers. As vehicle speed increases, throttle position reaches 25 percent or greater and engine speed reaches 3500 RPM, the EFCM commands the vacuum solenoid off. This causes the valves to open, diverting exhaust flow through an un-baffled path inside the mufflers, thus enhancing engine performance.
Competition Mode
When traction control is driver disabled, vehicle speed increases, throttle position reaches 25 percent or greater and engine speed reaches 3000 RPM, the EFCM commands the vacuum solenoid off. This causes the valves to open; diverting exhaust flow through an un-baffled path inside the mufflers more frequently and at lower engine speeds.
The system also delays exhaust valve activity during wide-open throttle acceleration to inhibit exhaust valve actuation when the accelerator pedal is released and reapplied while shifting gears.
The EFCM has the ability to detect electrical malfunctions within the system. Any electrical malfunction detected will cause the system to be disabled and increased exhaust audibility.
The system uses the engine control module (ECM), body control module (BCM), electronic brake control module (EBCM), EFCM, exhaust flow control valve vacuum solenoid, vacuum reservoir, vacuum lines, 2 exhaust flow control valves and the serial data circuit to perform the system functions.
The Exhaust Flow Control (EFC) System enhances engine performance. The system has 2 modes of operation:
• Normal
• Competition
Normal Mode
When the vehicle is stationary with the engine running the exhaust flow control module (EFCM) commands the vacuum solenoid On, which supplies engine vacuum to both exhaust flow control valves. This causes the valves to close, diverting exhaust flow through a baffled path inside the mufflers. As vehicle speed increases, throttle position reaches 25 percent or greater and engine speed reaches 3500 RPM, the EFCM commands the vacuum solenoid off. This causes the valves to open, diverting exhaust flow through an un-baffled path inside the mufflers, thus enhancing engine performance.
Competition Mode
When traction control is driver disabled, vehicle speed increases, throttle position reaches 25 percent or greater and engine speed reaches 3000 RPM, the EFCM commands the vacuum solenoid off. This causes the valves to open; diverting exhaust flow through an un-baffled path inside the mufflers more frequently and at lower engine speeds.
The system also delays exhaust valve activity during wide-open throttle acceleration to inhibit exhaust valve actuation when the accelerator pedal is released and reapplied while shifting gears.
The EFCM has the ability to detect electrical malfunctions within the system. Any electrical malfunction detected will cause the system to be disabled and increased exhaust audibility.
The system uses the engine control module (ECM), body control module (BCM), electronic brake control module (EBCM), EFCM, exhaust flow control valve vacuum solenoid, vacuum reservoir, vacuum lines, 2 exhaust flow control valves and the serial data circuit to perform the system functions.
Bob
01-17-2011, 03:08 PM
#5
Melting Slicks
Thread Starter
Thanks Bryan for the kudos and thanks Bob for the information. I read somewhere that the ZR1 exhaust flaps open and close possibly sooner than the Z06 I just can't find where I read it.
01-17-2011, 07:42 PM
#6
Race Director
If you don't have somewhere around at least 25% throttle, the valves won't open at 3,000.
The LS9 valves are programmed slightly differently from the valves in an LS3 or LS7 car. Take a look at this Motor Trend report:
http://www.motortrend.com/roadtests/...ing_specs.html
You'll see in there:
Both variants use an exhaust valve in the muffler, but the Z06's opens at 3500 rpm and still includes some sound-attenuating perforations, while the ZR1's opens more of a straight shot at 3000 rpm.
Bob
01-17-2011, 08:37 PM
#7
Melting Slicks
Thread Starter
The ZR1 butterfly valves open at 3,000 RPM - if you've got enough throttle!!
If you don't have somewhere around at least 25% throttle, the valves won't open at 3,000.
The LS9 valves are programmed slightly differently from the valves in an LS3 or LS7 car. Take a look at this Motor Trend report:
http://www.motortrend.com/roadtests/...ing_specs.html
You'll see in there:
Bob
If you don't have somewhere around at least 25% throttle, the valves won't open at 3,000.
The LS9 valves are programmed slightly differently from the valves in an LS3 or LS7 car. Take a look at this Motor Trend report:
http://www.motortrend.com/roadtests/...ing_specs.html
You'll see in there:
Bob
