1989 Chevy 5.7 need new catalytic to pass CA smog

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Picked up an old C2500 with 240k, runs great. Failed smog due to way high HC (~230 when max is 96). Passed on CO and NO. Tester recommended adding a new catalytic converter. Apparently a shop will do it for ~$300 but I kinda want to do it myself. So, the question is which one do I need? A cheaper "universal" one or more expensive 50-states CARB compliant one? Already did a tune up with new plugs and cleaned TB and added some injector cleaner to gas tank.
 
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If you are ordering online, you don't have the option of a universal one. The retailers won't sell you a non CARB one.
 

zanzabar

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Originally Posted By: Rand
if it only failed hc I wouldnt be sure it needed a new one.
Explain please? High HC only is a sign of just poor combustion that might be fixed with tuneup or what?
 
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Originally Posted By: zanzabar
Picked up an old C2500 with 240k, runs great. Failed smog due to way high HC (~230 when max is 96). Passed on CO and NO. Tester recommended adding a new catalytic converter. Apparently a shop will do it for ~$300 but I kinda want to do it myself. So, the question is which one do I need? A cheaper "universal" one or more expensive 50-states CARB compliant one? Already did a tune up with new plugs and cleaned TB and added some injector cleaner to gas tank.
CA has some pretty strict rules you need to follow and you need the CA-specific ones, possibly some paperwork also.... http://www.magnaflow.com/02catalytic_con...p;splityear=PRE www.hottexhaust.com usually has coupons that you can find online. have fun with that.
 
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Don't waste your money on a non-certified cat. Get the real deal the first time around. I've been through it with an 84 Civic and they will look for the number stamped in the cat. No number, no cert.
 
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Interesting on how picky some smog stations must be. I have a 91 Chevy 1500 with the 350 and I bought a universal cat from Summit online and welded it on myself and the truck has passed the last two tries with no hassles.
 

zanzabar

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Originally Posted By: Chris142
do the plugs,wires,cap and rotor plus change the oil. strange as it sounds clean oil will lower the hc's. i assume from gasses coming from the crankcase via the pcv system
[censored], I should have done that. I just dropped it off at the tester. frown
 
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Originally Posted By: morepwr
Interesting on how picky some smog stations must be. I have a 91 Chevy 1500 with the 350 and I bought a universal cat from Summit online and welded it on myself and the truck has passed the last two tries with no hassles.
It is within the last 4 years or so that all cats have to be direct fit here. Previously it was for OBDII cars only.
 
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Full tune up, fuel injector cleaner, oil change (check the PCV valve), and a good old Italian tune up. Then, take it from there.
 
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How to use a universal catalyst in Kalifornia: Buy universal cat, making sure of its dimensions. Remove stock cat. Carefully open up and gut stock cat. Install universal cat inside. Seal stock cat. Install on vehicle. Drive.
 
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If you end up needing a CAT Flowmaster has then for $222.00 for your truck with all the right certs and numbers. Tune that thing up though. Makes a huge difference.
 
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Tune up, check the ignition timing, and run it hard prior to the retest. A few hard runs will help clean up the existing converter.
 

zanzabar

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Failed 2nd test after the tuneup almost as bad as the first test. Ran it over to the exhaust shop and $350 later had a new cat and new Flowmaster muffler. The guy at the shop was explaining how stringent the testers can be so I'm glad I didn't try to do it myself. Part numbers have to match exactly, they become outdated every few years, etc., sounds like a nightmare.
 
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The other thing that can cause high HC is an oxygen sensor. I'm sure if your sensor hasn't ever been replaced, it is probably slow to react, causing increased smog. OBDI computers typically only set an O2S error code when the sensor voltage is completely out of range, so an O2S that is slow to react will still be considered okay by the OBDI computer. One nice thing about replacement cats is that they aren't pellet style. GM used those on their trucks until 1995. Those pellet cats always created more backpressure than grid style cats.
 
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