Trying to get ahead of emissions next year

[Laxplayer7]

2 catalytic converters

1990 k1500 350.

My trucks exhaust system is all jacked up. It's been cut and welded and clamped and everything. Got it like that from the dealer.

I have emissions where I live (AZ) and it looks like this truck has the original pancake cat and what looks like a no name brand aftermarket cat in line to a turndown pipe out the side.

If I wanted to clean this up would I be able to get away with a single magnaflow cat into a muffler and out the back? Or should I put 2 magnaflow cats in to a muffler and out the back?

I'm assuming it has 2 cats so it can pass emissions and I don't want to take off the pancake and then it not pass haha .

I'm sure the rough emissions is from leaking valve stem seals.

Thoughts?

 

[PlayingWithTBI]

I'm assuming it has 2 cats so it can pass emissions and I don't want to take off the pancake and then it not pass haha .

The truck originally came with one 2 way "pellet style" (pancake) cat. When they look and see 2, they may fail you on inspection. Find a 3-way cat that is 48 state approved (I don't think AZ has adopted all CA requirements YET) which will also help on your Hydrocarbons too. YMMV

 

[Laxplayer7]

What would the benefit of a 3 way be?

 

[PlayingWithTBI]

What would the benefit of a 3 way be?

It helps reduce HCs which is one of the reasons they don't use EGRs anymore on newer vehicles. The Pellet Cat is way more restrictive too. You'll gain power and MPGs just by getting rid of that thing.

 

[F4U-1A]

It helps reduce HCs which is one of the reasons they don't use EGRs anymore on newer vehicles. The Pellet Cat is way more restrictive too. You'll gain power and MPGs just by getting rid of that thing.

Clad this subject came up. I fired up the Chevy Saturday ( been sitting 3 weeks). Have a rattling sound underneath drivers side when I release the throttle, Cat breaking up? Only have about 100K miles.

 

[smdk2500]

Clad this subject came up. I fired up the Chevy Saturday ( been sitting 3 weeks). Have a rattling sound underneath drivers side when I release the throttle, Cat breaking up? Only have about 100K miles.

Probably not the cat since its on the passenger side. The noise could be transferring over though.

 

[L31MaxExpress]

It helps reduce HCs which is one of the reasons they don't use EGRs anymore on newer vehicles. The Pellet Cat is way more restrictive too. You'll gain power and MPGs just by getting rid of that thing.

The 3rd part of the 3-way actually oxidizes NOx emissions into harmless Nitrogen and Oxygen. You had the right idea just the wrong emission gas.

 

[PlayingWithTBI]

The 3rd part of the 3-way actually oxidizes NOx emissions into harmless Nitrogen and Oxygen. You had the right idea just the wrong emission gas.

Yeah, my bad - of course I meant NOx - I really did! Thanks for that...

 

[L31MaxExpress]

I do not have smog inspections on my 1987 G20 here, but I added dual 2.5" Walker OBD2 compliant 3 way cats on it. Runs extremely clean with the sequential EFI and Vortec heads on it. Since it has a L31 engine I set it up with the correct catalyst configuration for the L31 350. The other option that works nice is a dual inlet catalytic converter. The aftermarket cat replacements for the 4.3L and 5.0L Express van use a dual inlet/single outlet cat with an 02 sensor provision in the front of the catalyst body itself. Nice, clean setup.

 

[F4U-1A]

Probably not the cat since its on the passenger side. The noise could be transferring over though.

You are right, I try not to crawl around under the truck when the bugs are out ( but I just did, I forgot) It is my 3.8 JK that has both a Cat on the driver/ passenger side.