Butterfly Valve wide open

I have been experiencing some unpleasant rattling noises at low RPMs after checking out forums etc i narrowed it down to my exhaust butterfly valve not fully opening or closing. I assumed that it was not closing properly and was therefore causing the rattle. I checked it whilst the engine was off and at idle and it is wide open. I thought i was just going to attempt the gold tee/cable tie fix to keep it wide open at low RPMs both solving the rattle and giving a nice exhaust note. However seeing as it is already wide open all the time without any deliberate modifications and the fact that is rattles still, does this mean that i need a new actuator?

Originally Posted by 8355adam

I have been experiencing some unpleasant rattling noises at low RPMs after checking out forums etc i narrowed it down to my exhaust butterfly valve not fully opening or closing. I assumed that it was not closing properly and was therefore causing the rattle. I checked it whilst the engine was off and at idle and it is wide open. I thought i was just going to attempt the gold tee/cable tie fix to keep it wide open at low RPMs both solving the rattle and giving a nice exhaust note. However seeing as it is already wide open all the time without any deliberate modifications and the fact that is rattles still, does this mean that i need a new actuator?

So, you look up the tail pipe and butterfly's open & immobile @ idle? You can feel exhaust coming out and sounds loud?

Vac line wire tie works wonders, but JB4 does it better in software.

Originally Posted by CALWATERBOY

So, you look up the tail pipe and butterfly's open & immobile @ idle? You can feel exhaust coming out and sounds loud?

Vac line wire tie works wonders, but JB4 does it better in software.

Correct. It is wide open at idle with exhaust coming out. I was never attempting to get a good exhaust sound i just wanted the low rpm rattle i had to go away. I figured that keeping it all the way open with the vacuum tie method might do the trick but if its already wide open does this mean my actuator is faulty and does not close it at all if it is open at idle and when the engine is off. i have no reason to golf tee/tie the hose off if it doesnt work anyway. Maybe there is only enough vacuum pressure in the hose at certain rpms and that is when i can hear the rattle.

Originally Posted by 8355adam

Correct. It is wide open at idle with exhaust coming out. I was never attempting to get a good exhaust sound i just wanted the low rpm rattle i had to go away. I figured that keeping it all the way open with the vacuum tie method might do the trick but if its already wide open does this mean my actuator is faulty and does not close it at all if it is open at idle and when the engine is off. i have no reason to golf tee/tie the hose off if it doesnt work anyway. Maybe there is only enough vacuum pressure in the hose at certain rpms and that is when i can hear the rattle.

Try a zip tie - a nothing job and then you'll know.

I like disabling the flap, but don't find the note very pleasing, vs, say, the sweet sound of a 60's Triumph bike. Othern' that, disabled flap is very good indeed.

most likely wont cure the rattle though right?

Originally Posted by 8355adam

most likely wont cure the rattle though right?

Won't know 'til it's tried - 30 sec to conclusion.

OP?

Originally Posted by CALWATERBOY

Won't know 'til it's tried - 30 sec to conclusion.

OP?

CALWATERBOY,
In your experience with this mod, any truth to the web populated old wives tale that this open butterfly mod effects low end torque in a negative way? I have searched but have not seen anything that proves or even disproves this affect.

Originally Posted by daytrader

CALWATERBOY,
In your experience with this mod, any truth to the web populated old wives tale that this open butterfly mod effects low end torque in a negative way? I have searched but have not seen anything that proves or even disproves this affect.

Low end torque feels increased in mine. Much uncertainty and lag gone baby, gone! No effect on emissions but milage may dip if spending much time in stop n go -- can't get something for nothing.

.

I have mine locked open using the JB4, prior to that I unplugged it in the trunk. My butt dyno can't feel any effect one way or another & I don't see any effect on mileage. I just like the sound.

Originally Posted by bear-avhistory

I have mine locked open using the JB4, prior to that I unplugged it in the trunk. My butt dyno can't feel any effect one way or another & I don't see any effect on mileage. I just like the sound.

Wondering if back press diff, flap closed vs open, had been measured. Direct effect on engine feel & turbo runup.

Flap disabled, my ride's closest ever to feel of natural aspiration. Prior, had to put my foot completely flat on the go pedal to get smooth response from a full stop. Forgiving to a degree now.

Might be. I have my tip-in adjusted through the JB4 to a bit softer so that might mask any effect.

Originally Posted by CALWATERBOY

Wondering if back press diff, flap closed vs open, had been measured. Direct effect on engine feel & turbo runup.

Flap disabled, my ride's closest ever to feel of natural aspiration. Prior, had to put my foot completely flat on the go pedal to get smooth response from a full stop. Forgiving to a degree now.

With this mod enabled, a smoother low end response is what I had experienced in the past also, that could explain the false sense of reported negative torque loss.

I agree it would be nice to see measurements before and after.

OP, did you ever get to the bottom of this?
My valve also seems to always be open (minus the rattle). I wanted to do the "golf tee mod," but if my valve is already open then why do the mod?

The exhaust flap is open at idle even without the golf tee mod. With the windows open you can even hear it close as you start to drive away.

Here is how it works (at least on my car so I'm assuming this is true for other 335's):

Without golf tee mod:
Idle - open
Low RPM's while driving - closed
Higher RPM's - open

With golf tee mod:
Always open