L77 running rough

[Lachy_jeffery01]

Gday, I’ve just put 3 inch cat back, 3 inch high flow cats and 1 7/8 headers on my l77 and now it’s rough taking off and feels abit weird but doesn’t lose any power in the higher gears. It also ideals abit rough every few seconds also. I got a code saying mis firing cylinder so I got all my spark plugs redone. Seems abit better now with no engine light. Could this be happening coz I need a tune?

 

[lmoengnr]

Gday, I’ve just put 3 inch cat back, 3 inch high flow cats and 1 7/8 headers on my l77 and now it’s rough taking off and feels abit weird but doesn’t lose any power in the higher gears. It also ideals abit rough every few seconds also. I got a code saying mis firing cylinder so I got all my spark plugs redone. Seems abit better now with no engine light. Could this be happening coz I need a tune?

Get a tune, and make sure the plug leads aren't shorting on the headers (or melting).

 

[Lachy_jeffery01]

Get a tune, and make sure the plug leads aren't shorting on the headers (or melting).

Would needing a tune be something that could cause abit of a rough ideal and like a lag of power down low?

 

[Skylarking]

There are quite a few threads about exhaust systems within the forum. And many opinions exist about what sounds good.

But just must keep in mind that an engine is an air pump and the factory intake and exhaust systems are integral to the engine behaviour (and efficiency) which the factory tune provides. Change the exhaust system drastically and the factory tune may no longer provide optimal operation and you may experience poor driving behaviour as you now seem to be suffering from.

So best read the following comment a couple of times and consider how you use the car and what you expect to gain from your mods…

https://forums.justcommodores.com.au/threads/exhaust-system.303647/post-3424342

Then once you’ve armed yourself with some knowledge you’d be better able to assess where you now, where you are going and where you want to be…

Why because modding your car without rational goals and expectations in mind can be a rather expensive endeavour as you often end up not liking the results and then rip them out maybe getting 1/2 your money or less back by on selling your mistake to someone else

 

[Jeda]

Gday, I’ve just put 3 inch cat back, 3 inch high flow cats and 1 7/8 headers on my l77 and now it’s rough taking off and feels abit weird but doesn’t lose any power in the higher gears. It also ideals abit rough every few seconds also. I got a code saying mis firing cylinder so I got all my spark plugs redone. Seems abit better now with no engine light. Could this be happening coz I need a tune?

You need a tune.

 

[Phillbo]

Tune as your oxy sensors are way out with the high flow cats. The rear sensors are normally turned off through the tune