how to tell bad cats?

BlackVert

15 Year Member

Oct 3, 2003

5,589

9

98

Bethesda, MD

Nov 17, 2004

#1

• Nov 17, 2004

• #1

how can you tell if your cats are clogged?

 

M

mackey

Active Member

Jan 25, 2003

1,284

1

38

Beverly, Massachusetts

Nov 17, 2004

#2

• Nov 17, 2004

• #2

With my old car I couldn't go over 50mph.

 

9

95redSVT

New Member

Dec 20, 2003

35

0

0

Nov 17, 2004

#3

• Nov 17, 2004

• #3

bad cats? they piss and **** on everything in the house, claw up the chai....oh those cats

Not sure...mine have never given me a problem. They work well as wheel chauks

 

gcomfx.com

Founding Member

Oct 22, 2002

3,690

0

56

Republic, MO

Nov 17, 2004

#4

• Nov 17, 2004

• #4

It'll definately hurt gas mileage and top end of each gear. But I'm not sure how you actually test them.

 

gcomfx.com

Founding Member

Oct 22, 2002

3,690

0

56

Republic, MO

Nov 17, 2004

#5

• Nov 17, 2004

• #5

95redSVT said:

bad cats? they piss and **** on everything in the house, claw up the chai....oh those cats

Not sure...mine have never given me a problem. They work well as wheel chauks

Click to expand...

Makes them easier to kick when they are bad too.

 

Mrgreen94gt

SIMMA DA NA!!!

Founding Member

Jul 16, 2002

448

0

0

West TN

Nov 17, 2004

#6

• Nov 17, 2004

• #6

From what I've read, they tend to glow red when clogged. They also may rattle a bit.

 

95strokerPSU

Member

Jul 29, 2004

986

1

19

Sacramento from Philly

Nov 17, 2004

#7

• Nov 17, 2004

• #7

mackey said:

With my old car I couldn't go over 50mph.

Click to expand...

Exactly. You'll know if they're bad just from the lack of performance. My first Mustang was a 2000 V6 and the cats melted down. In trying to figure out what the problem was the car was put on a dyno and was only putting 90HP to the rear wheels. I had a check engine light too.

 

HISSIN50

"How long does it take to get help in here?

15 Year Member

Nov 29, 1999

31,179

34

129

Nov 18, 2004

#8

• Nov 18, 2004

• #8

with any exhaust restriction one can set up a vac gauge. rev up to a given RPM (say 3K). hold it super steady and watch the gauge. if the vac begins to drop, that suggests an exhaust restriction. diagnose the system from there.

good luck.

 

1

1hot5.0

Founding Member

Sep 6, 2002

1,615

0

0

Surprise, Arizona

Nov 18, 2004

#9

• Nov 18, 2004

• #9

Couldn't you hear pinging as well? When I first bought my car, it pinged bad with the stock h-pipe. As soon as I switched to my Bassani catted x-pipe, the pinging went away completly.

 

Venom351R

Founding Member

Apr 27, 2002

4,548

41

98

MAINE

Nov 18, 2004

#10

• Nov 18, 2004

• #10

BlackVert said:

how can you tell if your cats are clogged?

Click to expand...

usually mine spits up a hair ball

 

Joes95GT

New Member

Jan 23, 2003

3,132

1

0

Delaware

Nov 18, 2004

#11

• Nov 18, 2004

• #11

I had a clogged cat eons ago when I still had the stock H-pipe on the car. The car bucked like I was learning to drive a stick shift all over again. It did this while driving and it took about 2 minutes for the car to get up to 40 MPH (and no, I wasn't flooring it).

You'll know it if the converter is clogged. The car will be slower than a lawnmower.

Joe

 

T

Touring23

Founding Member

Dec 29, 2001

294

0

0

Washington

Nov 18, 2004

#12

• Nov 18, 2004

• #12

Measure the back pressure. Seriously.
http://home.earthlink.net/~touring23/backpressuretest.jpg

 

DFG 5OH

Active Member

Aug 28, 2004

1,341

0

36

Louisville, KY

Nov 18, 2004

#13

• Nov 18, 2004

• #13

i heard you can unplug the o2 sensors, to relieve pressure and see how things go then.

 

94CobraPace

Founding Member

Aug 30, 2000

907

1

0

Houston, Tx.

Nov 18, 2004

#14

• Nov 18, 2004

• #14

The muffler shop I went to check the before cat & after cat temp & said it was bad, the temp was the same in & out. And no don't try to check you pet cats temp front & back, not a good idea..

 

HoofnIt

Founding Member

Jan 8, 2001

1,175

0

36

North Carolina

Nov 18, 2004

#15

• Nov 18, 2004

• #15

If the temp is the same, incoming and exiting, then why would they be bad? I've heard that when the cats are clogged or bad the cats will get extremely hot. If you have a laser/digital thermometer you can point it on the cats and get a temp.

 

Black Sun 5.0

Founding Member

Mar 23, 2002

1,337

0

36

L.I., N.Y.

Nov 18, 2004

#16

• Nov 18, 2004

• #16

From what I know of cats, they should be hotter, so the laser pointer isn't really the best way to go. You can bring the car to a shop and have the back pressure tested.

 

ProKiller

Founding Member

Apr 26, 2002

3,064

15

78

PA

Nov 18, 2004

#17

• Nov 18, 2004

• #17

just take the stupid things off. get an h-pipe, keep the cats for inspection purposes. end of story.

 

mo_dingo

20+ Year Stangneter

Aug 26, 2003

3,031

2

58

Tucson, AZ

Nov 18, 2004

#18

• Nov 18, 2004

• #18

ProKiller said:

just take the stupid things off. get an h-pipe, keep the cats for inspection purposes. end of story.

Click to expand...

But if they are clogged, then you won't pass inspection. Just saying.

Time for an o/r midpipe.
Scott

 

1994Vib.RedGT

Member

Aug 19, 2004

585

0

16

Denver, CO

Nov 18, 2004

#19

• Nov 18, 2004

• #19

I dont know what would be wrong with them for this, but i remember one time the cats went bad on my moms Buick, and there was that sulfur/rotten egg smell. It was god awful

 

HISSIN50

"How long does it take to get help in here?

15 Year Member

Nov 29, 1999

31,179

34

129

Nov 18, 2004

#20

• Nov 18, 2004

• #20

matthiasj said:

i heard you can unplug the o2 sensors, to relieve pressure and see how things go then.

Click to expand...

some folks will drill a small hole just before the cat. if air is screaming out the hole, that can suggest a bad (plugged) cat. same idea but w/o the variable of the car running funky w/o its lambda hooked up.