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Catalitic Converters



My 91 may need new cats to pass emissions so I can renew the tags. Due to the extreme cost of these, are there any alternatives that might get me through?
I've had good luck with the Random cats.

the really high flowing cats are the new chevy truck

the 90 manifolds have the cats built in so you will have to cut them off and modify the manifolds or get headers which are rare and expensive.

I'm going to headers and removable cats soon. worth it!!!

Just had my stock 1990 ZR-1 emission tested for the New MA. State Dyno Inspection, and was amazed at the readings for a 10 year old car. :)

HC GPM----00.03----03.76
CO GPM----000.86---036.38
NOX GPM---00.38----05.77
CO2 GPM---583.17

Seems the Early Cats do a pretty good job as long as they're not broken up!

Why do you feel you may need new Cats.
My pollutant levels are:

HC - 1.57 g/mile...Limit = 1.20
NOX - 4.42 g/mile...Limit = 3.00
CO - 10.3 g/mile...Limit = 30.0

Failing both the Hc & Nox tests may indicate converter problems. It has a chip. We're going to put a stock one in and retest. The test is done on a dyno. The driver gets into 4th at 30mph. Wish me luck.
It has a chip ? well thats ok I understood what you ment...
Reprogram the computer back to stock and if you changed to a 160 degree t/stat change that back also. You'll be doing your car a huge favor if your use the stock 180 degree t/stat. I can elaborate on that subject if you need me too.
There is no way a 96 needs a new cat.

Guldstrand Motorsports
LOL Oh Man, Did I mess that one all up, chalk it up to having a 101 temperature. A 91 does have a replaceable chip sorry...... diregard that entire post, except for the t/stat thing

Going back to bed w/ the Nyquil®


Sounds like a good idea to put the Stock Chip back in. Could be the cause.

Perhaps your having a problem with the fact that the early ZR1's didn't have valve seals installed like the later MY's, and your burning a little oil! :(

GS796 is correct about making sure your ZR1 is up to it's stock operating temperature. I always take mine out for a good Three Digit Blast on the expressway before going for the state inspection! Cleans it Out!! :L
Thanks, everyone for your suggestions on this topic. I reinstalled the stock chip, changed the fuel filter, cleaned some sensors, and retested. It passed with room to spare.

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