jwillman

So I am now thinking my CAT is shot.

I have an intermittent rattle from under shifter like rocks in a can at low rpm/ idle and my case mileage has drop to 5 MPG!

Texas does not have emissions testing. Delete the cat or am I asking for more problems with my CIS if I delete?

The Forgotten On

The rattling could be something to do with the torque tube. The only way to be sure is to remove the cat and give it a shake.

If any of the honeycomb matrix inside falls out or it rattles it is your cat going bad.

Deleting it has no adverse affects on your CIS as it has no O2 sensor and will give you less issues in the long run as it won't clog up like a cat can.

Jetdriver69

Deleted the air pump, all the plumbing, engine driven fan, aux fan and cat in my 82.

A welder cut out the cat, welded in a piece of steel pipe with an O2 bung.

Haven't had any problems at all. The exhaust sounds great with a Borla cat back stainless steel system.

Chuck Schreiber

Delete it jay.

SMTCapeCod

That 5 mpg isn't catching anyone's attention? Or am i not supposed to read that literally.

Could be that your dumping fuel due to being overpressure or an obstruction in the injectors keeping them open, and the rattle is from liquid fuel coming under compression or getting flashed off when it gets downstream to the cat and ignites.

Its a reach but that mpg deserved additional thinking imho.

jwillman

The injectors are new short MB style.

I have been dealing with some hunting/ varying idle conditions and could very well be running rich but I am sort of at which came first, the egg and chicken point here.

I just jacked up the car and the cat has a pronounced rattle when I tap on it with a rubber mallet.

Seems no matter what that needs to go to eliminate exhaust caused issues.

tailpipe

Just poke the guts out of the cat with a steel rod then put the empty shell back on easy job.

jwillman

Unfortunately the PO welded the cat to the Y pipe and exit pipe so it will have to be cut out.

LT Texan

Did this to mine. A good way to go.

jwillman

Well I broke down and had the Cat replaced at an exhaust shop today, car would not stay running at idle. Cat was completely clogged.

Exhaust guy also noticed my intermediate and rear mufflers have some issues so they need attention.

Don't want to spend the money on a Borla Cat back.

What more reasonably priced options do I have?

The Forgotten On

A used system from 928 int. is a cost effective option or you could have a custom system installed locally from a good shop.

Otherwise you could have the shop patch it or replace pieces of the pipe, even though it may not look pretty, it will get the job done until you get a better system.

Mrmerlin

whats not to like?
This would be my choice.

NOTE by the time you get done messing around fixing the old ex system,
you could have nearly paid for the Borla.

Goodluck on your decision.

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