VY S Mods and Performance Problems

[thatbrynguy]

Hi,

I'm just looking for anyone who can give a bit of advice.

Currently I have a (mostly) stock VY S, the only mod on it so far is a Lukey 2.5" Cat back exhaust. I've got my eye on some of the induction mods from MACE. Though I'm a bit reluctant to jump in and start installing them because since installing the cat back my car's performance and fuel consumption are actually worse, and I don't really know why.

Fuel consumption has gone up by nearly 3L/100km, and while the car didn't have loads of power when I first got it, it still idled smoother, had better pickup and sharper throttle response, where as now, idle is rough, pickup at low revs is woeful and the throttle response just feels worse somehow, also it feels like the shift points on the auto are all wrong now.

Is this just a simple matter of that I should've had a custom tune done after the exhaust? And is it likely that if I go and modify the car any further I'm going to have the same disappointment?

I'm looking to install the 69mm throttle body, 85mm MAF, 12mm manifold insulator, 12mm plenum spacer, and a CAI of some sort (I'm not sold on the one from MACE, I prefer the look of the SS Inductions Growler but they seem a bit over priced and I've heard some people say theyre outright useless).

I hope I haven't gone and packed too much into this thread, but if anyone can give me a clue as to why my exhaust is giving me grief, or if anyone has installed the above mods from MACE I'd love to hear your thoughts.

Cheers!

 

[Jezza]

catback exhaust would only cause more fuel to be used if your giving the car more throttle to hear the exhaust otherwise it should get slightly better

i have a a pacemaker extractors going though a stock cat into a lukey 2.5" catback, mace 25mm manifold spacer, mace 82 degree thermostat and Mace cold air intake and the fuel economy has improved (when driven normally) and it also has more power

the mace cold air intake will perform the same if not better then the growler as the mace design will get more air then what the growler design does

 

[Dr HaxZaw]

No you shouldnt need a tune after the exhaust... sounds like you have some other issues with the car
Could be spark plugs and leads from the sound of it... try changing them if that doesnt fix it try your O2 sensors and also have a look in the How-to section and look at cleaning the intake

Cleaning your intake should sort out the idle problems if the spark plugs and leads dont

 

[thatbrynguy]

Thanks for your posts guys. I've given it some thought and I think instead of pouring money into a V6 I'm going to trade in and go for an LS1.

http://forums.justcommodores.com.au/showthread.php?p=2120490

Thanks again guys.