CILO

Hi all,

Ive been googlin around lookin for a good hi-flo cat and came across magnaflow. I noticed that they have the direct fit version for the 3.slows and was wondering if it contains the openings for the O2 sensors on it. I havent looked at my cat recently so if the openings for the O2 sensors are not on the factory cat (or pipes that stick out of it) please dont bash. Sometimes a newb's gotta ask a dumb question here & there. Anyway if anyone knows the answer to this it'd be much appreciated

thanks
Al

midiwall

Magnaflow offers a LOT of different cat models, including ones with the bungs already there (dunno if yours are or not). Your best bet is to get the part number off of the Magnaflow website, then go shopping online:

http://www.magnaflow.com/02product/02converters.asp

fwiw, I run a Magnaflow high-flow cat... Works swell.

And don't forget about eBay when shopping... I paid $56 shipped for mine.

Snorkeldepth

I have a Magnaflow direct-fit cat on my truck. I put it on a few months ago. The O2 sensor is in front of the cat . . . . at least on my truck . . . . . and there's only one. I may have my slightly used cat for sale here in the near future since I'm probably redoing my whole exhaust and will probably get a weld in unit.

CILO

Ok

took a look under the truck and noticed that i do have 2 O2 sensors but they are not attached to the cat or on its piping.

Snorkel, how has the cat served you? did it improve your trucks response?

CILO

Get this, just found out my truck is california emissions certified, hence the 2 O2 sensors.

Snorkeldepth

I thought the 2 sensors were an OBD II thing. I can't remember which year that started. My truck is a California truck but pre OBD II so only one sensor.

I found this:

"On-Board Diagnostic systems are in most cars and light trucks on the road today. During the '70s and early 1980's manufacturers started using electronic means to control engine functions and diagnose engine problems. This was primarily to meet EPA emission standards. Through the years on-board diagnostic systems have become more sophisticated. OBD-II, a new standard introduced in the mid-'90s, provides almost complete engine control and also monitors parts of the chassis, body and accessory devices, as well as the diagnostic control network of the car.

All cars built since January 1, 1996 have OBD-II systems. Manufacturers started incorporating OBD-II in various models as early as 1994. Some early OBD-II cars were not 100% compliant. <Click here> to see the dates OBD-II started being included on specific makes and models. "


I have had too many other issues to be able to say that the cat made a difference. I replaced my cat as part of my overall effort to rehabilitate my truck. The exhaust guys said they could just cut the brackets off and weld my Magnaflow into the system they design.

It seems pretty logical to conclude that having a cat that matches the rest of the exhaust system is a good thing. A free flowing exhaust with a restrictive cat sounds like it would negate the positive effects of the rest of the exhaust.

midiwall

The two O2 sensors serve different purposes.

The front one (i.e., in front of the cat, often mounted in the pipe between the Y and the cat) reads the O2 content in the exhaust and feeds the ECU so that it can adjust the fuel mixture for a 14.7:1 A/FR. The rear one (i.e., after the cat, before the muffler) is there to make sure that the exhaust is "cleaner" after the cat than going in. It has nothing to do with fuel economy or engine performance.

Now, to make things more fun... On 1999 and later Toyota rigs, the front sensor is actually a wideband A/FR sensor, not just an "O2 sensor". This is cool 'cause it gives the ECU more accurate info to work with, but it's a bummer 'cause it costs a lot more than an O2 sensor.

And! The CA thing kicks in when you start counting the number of cats you have. 49 states have just one, CA wants a 2nd one in there.