backfire after de-cat

[Welsh g60 0]

I've just replaced the cat on my g60 with a straight pipe (cut the cat behind the lambda probe) and now whenever I change gear when booting it I get a huge backfire. Do I just need to adjust the fueling or is there more to it?

[steveo29 0]

mine doesnt do that....is it sealed well?

[kongo127 0]

That seems cool mate! 8)

But not healthy for sure...

I don´t have the cat too, but it doesn´t make that huge backfire! :shock:

What i hear is some smooth poping from the exaust.

I´ve kinda like it! :-P

Check out your lambda probe harness because if it´s damaged the ECU will fuel up your engine to much!

If possible check your CO2 Pot resistence too (500ohm). :idea:

And if you have some time check the ignition timing too.

It helped mine to stop to much poping...

And i got more power from it! (advancing timing)

[bigbluec 0]

Mines done it ever since i bought it 2 years ago. Its to old to have a cat on it! (1990)

i've checked the mixture and it's perfect the only thing i can come up with is a slight leak in the inlet manifold but after 35k + it doesn't seem to have hurt mine (touching wood whilst typing!).

[Welsh g60 0]

thanks all, I think I'll take it for a tune up and see how it runs after that