spfi question.........

[GREENSUBIE]

with the spfi swap do you need a catalytic converter?

 

 

Thanks

SS

[NorthWet]

The SPFI system does not need/use/rely-on the catalytic converter for any of its functions. Emissions laws are a different matter.

[GeneralDisorder]

For the reccord, nowhere in my write up does it mention the need or use of a cat.

 

GD

[GREENSUBIE]

For the reccord, nowhere in my write up does it mention the need or use of a cat.

 

GD

 

 

 

I was just checking cuz my car has a cat. after the spfi install the car seems to run a little rich, i smell a hint of gas so i was going to take the cat out and see if it changed but i was told that the computer might need it or something with the o2 sensor i dont know. but ill just take it out. thanks

[Quidam]

with the spfi swap do you need a catalytic converter?

 

 

Thanks

SS

 

 

Depends:)

[GeneralDisorder]

Depends:)

 

It does not depend. The SPFI swap is entirely unassociated with the catalyst.

 

GD

[Gloyale]

You need an O2 sensor, but not nessacarily a Catalytic. Although, with Subies, that is where the O2 sensor lives.

[GeneralDisorder]

You need an O2 sensor, but not nessacarily a Catalytic. Although, with Subies, that is where the O2 sensor lives.

 

One should note thought that it's relatively trivial to add an O2 bung anywhere you like. They are widely availible due to the wideband O2 sensor market.

 

GD

[zyewdall]

I was just checking cuz my car has a cat. after the spfi install the car seems to run a little rich, i smell a hint of gas so i was going to take the cat out and see if it changed but i was told that the computer might need it or something with the o2 sensor i dont know. but ill just take it out. thanks

 

Wouldn't taking the cat out make it worse? As far as unburned HC in the exhaust? If it's running rich, then the cat will help burn some of the unburned gas at least.

 

Z

[Suberstar88]

To my understanding the cat is need on SPFI engines for backpressure, or thats what ive been told by countless people. Only thing stopping me from having the loudest subie in town.

[GeneralDisorder]

To my understanding the cat is need on SPFI engines for backpressure, or thats what ive been told by countless people. Only thing stopping me from having the loudest subie in town.

 

"Countless people" are wrong. There should be no backpressure in the exhaust system. Scavenging takes place in the headers prior to the y junction.

 

I have gutted the cat on every Subaru I've owned. Most (2/3 at least) are already broken up and half plugged anyway.

 

GD

[kingbobdole]

Wouldn't taking the cat out make it worse? As far as unburned HC in the exhaust? If it's running rich, then the cat will help burn some of the unburned gas at least.

 

Z

 

This is not an issue because the O2 sensor is upstream, before the cat. That is where you want it to get the best read because after the cat it will mostly always be "lean" and the engine will have to run super rich for the O2 behind the cat to get a rich signal.

 

Running catless is just stupid. Yeah, it's cheap and easy, but you don't really free up any power, all you do is pollute your rump roast off. Most areas tampering with equipment like that is illegal. Save the fricken earth.

[GeneralDisorder]

Running catless is just stupid. Yeah, it's cheap and easy, but you don't really free up any power, all you do is pollute your rump roast off. Most areas tampering with equipment like that is illegal. Save the fricken earth.

 

It's really a specious argument. Am I any worse than the thousands of pre-emissions muscle cars out there? Am I any worse than most Harley's? If I couldn't do what I wanted to with my 80's Subaru I would just go buy an ex-military Duece. The tiny minority of people such as myself make no dent in the millions of suckers that have already bought into the green craze and have purchased Priuses. Let them have their fad. I walk my own path.

 

Besides - I'm saving the "fricken" earth more than they are - I'm recycling (not because it's "green" mind you!) by not buying a new car every 3 to 5 years. There's more pollution made in createing one prius than me driving my catless 25 MPG Subaru for 3 to 5 years . The verdict was in a LONG time ago. It's industrial pollution that has got the bunny huggers all wadded up in their trousers. Manufacturing and consumption are to blame - consumption WAY beyond what is or was realistic or neccesary. I'll not be picking up the slack for all the consumers - thanks but I would rather see them rot in the bed they have made for themselves.

 

MORE consumption isn't going to fix the problem (if you consider it a problem - which I don't. So we get a few more desserts and Arizona has waterfront property? Sounds just fine to me). Seriously - we could use a population reduction. They say that after the black death wiped out 1/3 of the population of the known world there was 500 years of prosperity for those that were left - more jobs, more food, more land.... etc. Here I am at the top of food chain living in the US.... I'm golden. And hell yes I'm selfish like that!

 

GD

Edited May 18, 2009 by GeneralDisorder