gear_e

I have a stock '99 si except for the injen cai, and thinking to install 2.5" hi-flow cat. The issue is, I am using stock ecu, OBDII, and I guess that the CEL will lights as I install it and will get me poor gas mileage..

How to solve it? Any suggestion?
Sorry if this has been covered before...

Thanks.

JDMallTHEway

you can buy an 02 sim chip. they sell them on ebay. my friend bought one, and it works very well.

Hope this helps, let me know if you ahve any other questions.

civictildeath

http://www.defcon-racing.com/o2sim.html this will take care of cel

EMphaticONE

are there any setbacks, performance wise, when throwing a CEL due to the 2ndary O2 sensor?

civictildeath

my cel has been on since i put the hi flow cat on last august. i cant say ive noticed anything degrades performance wise. actually my car seems to run a bit better with the cel on (beat a integra with it on) but that is my car every one is a little different

huntarrr

no, your secondary o2 only tells if the cat is working properly or not. your primary o2 (in the exhaust manifold) is the one responsible for measuring air/fuel and sending it to the ecu...

someone correct me if i'm wrong

civictildeath

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by vsm98civic &raquo;</TD></TR><TR><TD CLASS="quote">no, your secondary o2 only tells if the cat is working properly or not. your primary o2 (in the exhaust manifold) is the one responsible for measuring air/fuel and sending it to the ecu...

someone correct me if i'm wrong </TD></TR></TABLE>
i dont know about that but like i said mine seems to run better with secondary o2 throwing cel but all cars are deifferent

JDMSiGuy17

i think if you switch to obd1, a chipped p28 or something you should be fine too because i believe that they only have one o2 sensor. and down the road depending on how into racing you are, you will probably get it anyways cause alot of people do.

huntarrr

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by civictildeath &raquo;</TD></TR><TR><TD CLASS="quote">
i dont know about that but like i said mine seems to run better with secondary o2 throwing cel but all cars are deifferent</TD></TR></TABLE>

Your car should never run 'better' with a CEL on.. you're probably just feeling a little gain with the high flow car you put on

Padawan

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by vsm98civic &raquo;</TD></TR><TR><TD CLASS="quote">no, your secondary o2 only tells if the cat is working properly or not. your primary o2 (in the exhaust manifold) is the one responsible for measuring air/fuel and sending it to the ecu...

someone correct me if i'm wrong </TD></TR></TABLE>

That is 100% correct. There is no performance or gas mileage penalty whatsoever because of a secondary O2 CEL.

JDMallTHEway

gear_e

so, basically use the hi-flow cat, and just neglect the CEL?
another way is to use o2 sim?

i heard there is some tricks to 'hang' 2nd o2 so it wouldn't lights on... have you heard about it? but i'm not sure on how to 'hang' it...

anyway, how's the performance gain with hi-flow cat v.s. stock cat?
will that effect gas mileage also?

Thanks

nwdave

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by gear_e &raquo;</TD></TR><TR><TD CLASS="quote">I have a stock '99 si except for the injen cai, and thinking to install 2.5" hi-flow cat. The issue is, I am using stock ecu, OBDII, and I guess that the CEL will lights as I install it and will get me poor gas mileage.. </TD></TR></TABLE>

You won't necessarily get a CEL. I ran a Carsound on my OBDII del Sol for over a year with no problems. One 02 was plugged into the header, one in the cat. Just make sure you buy a cat with an 02 bung on it.

pwrofdrm

The real question is..if your car is completely stock other than an intake, why are you dropping 200 on a high-flow cat? Money is better spent elsewhere. Not to mention the fact that if you buy one with 2.5in inlet/outlet you're going to need to buy two more flanges for you stock exhaust manifold and exhaust b-pipe to bolt onto...