It wouldnt run even in idle.Took advice and replaced the ignition module.Car ran, then I got a 54 code.Traced it to a bad oil pressure switch as well.It seems I had multiple trouble at one time.Go figure.Since my 91 is out of the range for emission testing in my state(NC),can I gut the catalytic converter or run a straight pipe for a lillte power or does the 3.1 need backpressure from the cat to perform better?

Ken

 

As far as back pressure my 2.8 and step dads 3.1 camaros our cars liked a full exhaust with a cat and no muffler (my step dads car when the muffler rusted off) or no cat and a muffler(my car).

 

'91 is out of the range for emission testing in nc. But, they still are supposed to do a visual inspection. You would need to gut the cat, and leave the shell so it looks like it is ok. You also can't run without a muffler here, or with a cutout. Or find a shop that does a 5 second inspection.

 

I don't think any motors need backpressure, what they need is velocity, and that could drop of if you go with too large pipes. Some call it backpressure, but it really isn't.

Maybe your exhaust is clogged, I had a dead rat in mine once, real ewey smell.

 

trust me these 3.1/2.8s sound like crap with straight pipe's

we got a 91 firebird in at work last week and its loud but dosnt sound at all powerful
it had a custom straight pipe

think of how many ***** cars sound thats how it sounded but much louder

pull the cat but keep a muffler of some type on there
these engines do like some back pressure
and besides they sound better aswell

 

Yeah that whole "engines need backpressure" is just one of those myths; don't even worry about it. The motor will run OK without a cat. In fact if that's the factory cat, the catalyst bed might be breaking up and clogging the exhaust.

But a new hi flo cat is $100 from Summitracing.com ... that's got my vote.