removing the cat

[snooper0069]

i have a 94 g.m.c. with a 5.7 . has anyone removed the cat to see if it gives any improvement . ( yes i know its illegal to do this).

mines the original and now its starting to smell like propane sometimes from the exhaust.

[k1500chevy97]

Better do something now before it breaks up and clogs the exhaust . that will f**k your engine up big time

I would not suggest getting rid of the cat at all i would suggest just getting a replacement installed

 

Reason why i would not suggest removing the cat is because i actually did on my 97 about a year and half ago and right away the service engine light came on and my gas mileage took a BIG dip down to about 12 mpg when regularly geting about 19 around the farm

[ADDZ71]

You might call your local dealer. I believe that the Feds require that the cats last 10 years / 100,000 miles. It would be in your manual also.

 

Good Luck.

[k1500chevy97]

Mine was 8/80

[ryanct]

Hey K1500,

 

You probably had the mileage problems in your 97 because of the oxygen sensors. If im not mistaken, '96+ have 4 O2 sensors, 2 of them after the cat. Without the cat, the signals from the after-cat sensors would be off, causing the computer to think that there's something wrong with the cat, hence the warning light.

 

In a '94 you shouldn't have any problems taking out the cat, since there's just the 1 sensor in the manifold.

 

I took out my cat with the original manifolds and muffler and everything and definitely noticed a performance and sound improvement. I've since gone to headers and dual exhaust, which is obviously much better.

[toboyca]

Hey K1500,

 

You probably had the mileage problems in your 97 because of the oxygen sensors. If im not mistaken, '96+ have 4 O2 sensors, 2 of them after the cat. Without the cat, the signals from the after-cat sensors would be off, causing the computer to think that there's something wrong with the cat, hence the warning light.

 

In a '94 you shouldn't have any problems taking out the cat, since there's just the 1 sensor in the manifold.

 

I took out my cat with the original manifolds and muffler and everything and definitely noticed a performance and sound improvement. I've since gone to headers and dual exhaust, which is obviously much better.

For those with 4 or more O2 Sensors... & wants to do without cat(s), you guys might want to research on O2 simulators to be plugged in in place of the O2 sensor(s) after the cat...

 

What this does is it will fool the ECM, telling it that everything is normal, thus, no engine codes or bad fuel mileage.

 

Those living in mandatory smog testing areas, u better have a back-up replacement cat (from a junk yard or someting) so that if a smog test is due, A cat & your original O2 could be retrofited. (just make sure they are made in such a way that all you have to do is bolt them on... rather that cut & weld... cut & weld. )

 

 

It involves a bit more work but if you guys really want to ride without cats, smog test or not... shouldn't stop u from doing it... would it?

[biff591]

where can you find 02 simulators for a 2001 silverado

[Tyler_LS1]

Here

 

 

o2 sim

 

Ebay 02 sims

[ryank1]

I've also seen where a spark plug anti fouler installed on the rear O2 sensors will fool the computer. A friend did this on his G35 and has not had any problems with the ses light.