emission testing

[DanStokes]

Remember, HC is just unburned fuel. Given the inherent combustion properties of internal combustion engines there's going to be some HC but a bad O2 sensor will make it difficult for the EFI to properly adjust itself. Still, the system expects to work with a functioning cat and the computer's tables are set up to give the tailpipe-out values required based on the cat being in the system. For a DD there is little to no advantage to not having a cat in the system so you might as well do it.

I've had excellent results with universal cats (Catco, for example) and I see no advantage to paying the big bucks for a factory replacement. I'm guessing that yours is a 3-way (1 HC/CO brick and 1 NoX brick) but I don't know if your vehicle has air injection between the bricks (some do and some don't). Either way, there are universal cats with the fittings you'll need.

FYI - the advantage of the factory-style cats is that they will light off quicker. While nice (environmentally) as a practical matter I don't think it matters much. The OEM's jump thru a lot of hoops to meet the cold start requirements but you certainly can take your vehicle in for testing with a warm system.

Dan

[TC]

If it is 6.40 on CO, you got a bad O2 sensor.........Drop the CO and the HC's will drop...............

[squirrel]

first post said he got a new O2 sensor, although he hasn't said yet whether or not he installed it. I'll assume he did.

[A/Fuel]

I did install it, over all the truck runs better, thats why I was a little puzzled.

[anotheridiot]

what year is the truck? I would think just putting the converter back on would take care of it. O2 sensors are used to adjust your mixtures and fuel pressure in newer trucks, a reason alot of small cars have electric fans that hardly ever go on. I am in IL so they are just mainly checking at the OBDII. If you dont show codes you pass. bigger trucks need to get the tube in the tailpipe too.
Try to get that exhaust hot before you get the piece of 02 sensor thats left in the pipe.

[A/Fuel]

It's a 1990.
I have a new question, how far back from the y pipe does the converter have to be to get hot enough? Or where do I need to put this thing?
There is a big long pipe there now, right to the muffler so there isn't any clues as to where the converter was origionaly.

[TC]

It's a 1990.
I have a new question, how far back from the y pipe does the converter have to be to get hot enough? Or where do I need to put this thing?
There is a big long pipe there now, right to the muffler so there isn't any clues as to where the converter was origionaly.

As close to the exhaust manifold as possible is where it needs to be mounted.......

Also you said you replaced the O2 sensor, is this a V8 truck??, because there are "2" O2 sensors if it is..........

It just seem awfully weird that it runs so high on the CO, when the 350 that used to be in my camaro with 10.5 compression and a 300 duration cam ran at 1.8 on the CO, and that's with a Carb and no Cats...........

Is there a way to turn up the idle?? That will bring down HC's and should lower the CO to........

[A/Fuel]

Thats what I was thinking, but I didn't know if there was such a thing as to close.

[TC]

Thats what I was thinking, but I didn't know if there was such a thing as to close.

Never to close, the Cats on my '99 camaro bolted to the exhaust manifold itself.......

But remember your O2 sensors need to be in front of the cat(s)......

[squirrel]

1990 probably has only one O2 sensor.

The cat should be right after the Y pipe, if you can fit it that far forward.