discopig

I am looking for some reassurance. My AFM valves have failed and GM is no longer going to be covering the replacement cost. Now that I am out of warranty, I am going to get the AFM/DoD tuned out. Do the valves fail in an open position? Always?

I have seen posts suggesting this, but I wanted to be sure. Basically I am wondering if I have to replace them with OEM, get an aftermarket exhaust system with new AFM (or without AFM valve) or get them removed from the exhaust prior to tuning. Or, can I just keep the stock exhaust, with the failed valves and tune out the AFM and tune out the check engine light (with the HPtuners instructions posted elsewhere on this forum)?

Is there a way for me to check that they are open?

Thanks!

Adam

ErnieN85

yes they fail open

WW7

That's why when you first get the car, If you want the exhaust to stay open you pull the number 42 fuse.

discopig

Isnt fuse 42 for the NPP valves (for sound) not the AFM valves (for v4-v8)? Maybe I'm mistaken.

ErnieN85

no you are corecct

corvettezman

NPP and AFM use the same physical valve for different purposes.

4*CRUIZN

NPP and AFM valves are separate. NPP Valves are on the back side of the mufflers, and the AFM Valves are in front of the mufflers. They are controlled separately.

Refer to this YouTube video at about the 14:30 mark.

Also, according to this video, the AFM Valves are normally open, and are closed when the AFM kicks in. This is to adjust back pressure. Hope this helps.
Regards,
John

ZO6LIFE

So much uninformed information out there 🤦‍♂️

discopig

I know... And hard to sort through some if it becuase some of the misinformed are so sure of their "information"!

There are a couple good threads here on the forum about the AFM/NPP valves, so that's not a concern to me. I am just looking for validation that they AFM valves fail open. Which seems to be the consensus.

96GS#007

They fail open as several have mentioned. If you want to save money on a tune, disconnect them and install simulators (glorified resistors since they're in the mating half of the connector). Zip-tie the each harness out of the way, and you're good to go. It'll take you longer to get the car in the air.

If the actuators are good, you can remove them from the pipes and store them for the next guy or sell them. There will Not be a hole where you remove them from. They attach to a small shaft that passes through the exhaust pipe.

corvettezman

To clarify, and sometimes that's what happens when you post at 4am.

The valve the AFM and the NPP use is the same part #

They are obviously used in different parts of car for different purposes but they are interchangeable.

Bill Dearborn

It isn't the valve that is the same part number. It is the valve actuator.

Bill

ShadyVette

As someone who had the AFM valves fail and replaced recently they fail open (v8 mode position).I didn’t realize the same actuators were used for both npp and the afm actuators but there are definitely two pairs. I’ve pulled my npp fuse. The afm actuators and electronics are part of the emissions system and I’ve put the awe fakers on them and put an awe exhaust on without the valves to reduce the heat on actuators / electronics so as to be able to pass emissions in the future. It’s annoying these actuators throw emissions CEL when they don’t work when they’re basically for sound asthetics