If you have an 89+ California car with pre-cat

935motorsports

Active Member
Mar 30, 2005
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San Diego, CA
If your car isn't responding well lately, consider replacing the pre-cat. It likes to get clogged.

A customer came in and I was not happy with the performance of the car. He didn't seem to mind (older gentleman), but I finally talked him into replacing the pre-cat with the older 87 non pre-cat style.

Unfortunately the pre-cat header pipe is longer to allow the mounting of the sub oxygen sensor. So the 87 style header wouldn't fit without some modifications.

I picked up a used pre-cat, but it was clogged as well.

We finally gutted the pre-cat and now the car pulls hard once again. We also added a stock turbo secondary cat, and stock catback (required mods), to replace the 1.5" exhaust that some other shop had installed.

This is just a tip, that before adding modifications, you should check to make sure your car is working properly first.

His car is still 100% stock (pre-89 spec), and pulls very nicely.

Pics:

His old exhaust, looks like it was made out of fence post:

p1479312_1.jpg



Catalytic converter damage. I poured oil on it before punching it out, to prevent toxic dust from flying around. Note the screen. That is hard to get out, but I was finally able to fish it out with a long screw driver.

p1479312_2.jpg
 

935motorsports

Active Member
Mar 30, 2005
2,569
0
36
47
San Diego, CA
He wanted it to look stock, which is why it was gutted rather than cut out.

When I went to gut it, the cat was already broken into about 3 pieces inside.

He still wants it to be "correct", so I'll still be looking to find a clean pre-cat for him.

His 2nd cat (cheap aftermarket) was also clogged, which is why I replaced it with a good stock one.