Bronco Forum - Full Size Ford Bronco Forum banner
1 - 18 of 18 Posts

·
Master Bater
Joined
·
7,268 Posts
Discussion Starter · #1 ·
Its been a LONG time since I swapped the y pipe and cat for a bassani set up. Im having trouble passing smog right now, and need to find something out.

Where does the stock air pump hose mount to the stock Y pipe or CAT(s) does it mount between the two cats, or is it before them in the Y pipe? A pic would be great too.
 

·
Satyr of the Midwest
Joined
·
17,738 Posts
Between the two beds:
 

·
my bko ate my money
Joined
·
2,319 Posts
thanks, but I got it worked out. The bassani pipe isnt great for us California guys anymore. they changed the smog rules on NOX and that pipe needs some massaging to work.
whats need to make it work for cali guys now??
 

·
Satyr of the Midwest
Joined
·
17,738 Posts

·
Master Bater
Joined
·
7,268 Posts
Discussion Starter · #7 ·
the bassani Y comes with the air injection tube prior to the cat, which negates the NOX reduction of the replacement cats. NOX was never a selection criteria previously (as I understand it) so I was failing for NOX. It requierd a CAT with a air injection tube in the middle of the cat. So I had to plug the injection at the collector and move it to the cat. the change was in the last two years, cause I passed no prob last time. (2 years ago)
 

·
Engineer
Joined
·
13,165 Posts
the bassani Y comes with the air injection tube prior to the cat, which negates the NOX reduction of the replacement cats. NOX was never a selection criteria previously (as I understand it) so I was failing for NOX. It requierd a CAT with a air injection tube in the middle of the cat. So I had to plug the injection at the collector and move it to the cat. the change was in the last two years, cause I passed no prob last time. (2 years ago)
Moving the air injection tube fixed the problem and it passed? Some how I'm not buying that solution. You didnt change anything else, fuel octane, engine temp, or anything else? Do you have the ppm reading on the NOX from both tests?
 

·
Satyr of the Midwest
Joined
·
17,738 Posts
It's true. The mapping in any setup that's NOT either a 1995 MAF with air injection, or 1996 with no air injection, needs the extra oxygen before the oxidation bed, not the reduction bed where NOx reduction occurs (which is where Bassani puts it IIRC).

Just a little (correct) Wiki info:

Many three-way catalytic converters utilize an air injection tube between the first (NOx reduction) and second (HC and CO oxidation) biscuits of the converter. This tube is fed by either an air pump or by an aspirator. The injected air provides oxygen for the catalyst's oxidizing reaction. These systems also sometimes include an upstream air injector to admit oxygen to the exhaust system before it reaches the catalytic converter. This precleans the extra-rich exhaust from a cold engine, and helps bring the catalytic converter quickly up to operating temperature.

Most newer systems do not employ air injection. Instead, they provide a constantly varying mixture that quickly and continually cycles between lean and rich to keep the first catalyst (NOx reduction) from becoming oxygen loaded, and to keep the second catalyst (CO oxidization) sufficiently oxygen-saturated. They also utilize several oxygen sensors to monitor the exhaust, at least one before the catalytic converter for each bank of cylinders, and one after the converter. Some systems contain the reduction and oxidation functions separately rather than in a common housing.
So this is why employing a TWC without an air pump, to a system designed to operate with air injection, may cause catalyst failure. It's not that the new catalysts are "more efficient," but that the cycling mixture on newer vehicles (and those 1995-6 Broncos with different mapping) provides appropriate conditions for reduction and oxidation.
 

·
Master Bater
Joined
·
7,268 Posts
Discussion Starter · #10 ·
yes I have them and yes its true. a partial explanation is that the front cat in the stock set up eliminates NOX, and the second HC's. Thus the air injection is after the first cat (Which doesnt want O2) and before the first (which does want it)
 

·
Registered
Joined
·
101 Posts
Here is a pic of the actual exhaust if it helps. You can see the AIR tube mount between the two cats.
:histerica
great when something just strikes you funny and you just cant stop laughing, this fn picture pffft
:histerica

sorry , not helping kick ya......... i swear :histerica

i just cant stop laughing.......there it is......that one..:histerica
 

·
Registered
Joined
·
258 Posts
So Cali can institute new emission laws on a vehicle that that is older than the law? That doesn't sound right because now the state is forcing vehicle owners to spend $100's to retro fit the vehicle to pass the inspections, dang that's pretty harsh. Normally the state would have a grandfather clause to exempt any cars prior to the laws. But hey it's Cali and I guess it's cheaper to change laws than to cut passages through the mountains and pollute Nevada, lol.

Glad I live in Texas
 

·
Satyr of the Midwest
Joined
·
17,738 Posts
I'm as confused as a baby in a tittie bar, but...
 

Attachments

·
Registered
Joined
·
3,213 Posts
:shrug Its a y-pipe that is junk from the first day of existance. Whats so funny?
 

·
Registered
Joined
·
94 Posts
That was good stuff.
 
1 - 18 of 18 Posts
Top