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VX L67 revs bouncing when foot is taken off..?

Rooney69

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Hi all. I have a VX series II S that is Supercharged and 4 speed auto (think they all are yeah?)

The car is completely stock apart from a twin 2.5" catback with a V8 rear resonator that has twin tips.

Now I have only noticed this problem ever since installing the exhaust on the car, because now I can hear the engine and ding ding I now see why they say commodore autos sound droney.

Basically if I let my foot of the accelerator at any speed above 40-50kph, the revs on the dash bounce between 1000 and 1500 and I literally hear the exhaust bouncing a note as I roll along. This is very noticeable if I come down a hill in D or 3rd (either one) and let my foot off doing say 65-80 it just proceeds to sound as if I am constantly touching the pedal like I want attention and it is driving me nuts!

Is this some kind of pressure build up that is normal, but only notice it now due to the exhaust?

Or a problem with the exhaust? Like, I am desperately trying to find a standard replacement online but it doesn't give me much to work with. Ps, I was dumb and threw the standard system out 6 months ago :[
 

lowandslow

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Completely normal for the L67. You just can't hear it with the standard pipes on.
 

EYY

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Deceleration fuel cutoff - it’s a fuel saving thing. But injectors need to come back in periodically to keep the engine going. That’s the fluctuation you’re noting. You’ll notice the ‘inst fuel’ will go down to 0 on heavy decel when this happens.

Nothing wrong with it at all - you’ll get used to it and won’t even notice soon
 

gohrdrgomad

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Hi all. I have a VX series II S that is Supercharged and 4 speed auto (think they all are yeah?)

The car is completely stock apart from a twin 2.5" catback with a V8 rear resonator that has twin tips.

Now I have only noticed this problem ever since installing the exhaust on the car, because now I can hear the engine and ding ding I now see why they say commodore autos sound droney.

Basically if I let my foot of the accelerator at any speed above 40-50kph, the revs on the dash bounce between 1000 and 1500 and I literally hear the exhaust bouncing a note as I roll along. This is very noticeable if I come down a hill in D or 3rd (either one) and let my foot off doing say 65-80 it just proceeds to sound as if I am constantly touching the pedal like I want attention and it is driving me nuts!

Is this some kind of pressure build up that is normal, but only notice it now due to the exhaust?

Or a problem with the exhaust? Like, I am desperately trying to find a standard replacement online but it doesn't give me much to work with. Ps, I was dumb and threw the standard system out 6 months ago :[
Amplifiers and subwoofers are a optional V6 extra for P platers with mod'd exhausts to assist.
 

Rooney69

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Normal for pretty much all Ecotecs/l67 unless disabled in the tune
Deceleration fuel cutoff - it’s a fuel saving thing. But injectors need to come back in periodically to keep the engine going. That’s the fluctuation you’re noting. You’ll notice the ‘inst fuel’ will go down to 0 on heavy decel when this happens.

Nothing wrong with it at all - you’ll get used to it and won’t even notice soon
I vaguely remember it used to do this before I got the exhaust, so yeah I am only hearing it now due to the exhaust.

Would it sound stupid from the outside? as though I am rolling by just revving like some idiot? I can definitely hear it inside the cabin and I think maybe installing good headers would make it at least sound better? sort of like a deeper burble or so on.
 
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