Concerns with my header and lack of an O2 sensor - Focaljet

**enviousdreamz** · 06-29-2008, 07:01 PM

I bought a cosworth header for my car almost 2 years ago and no problems, just a small leak which i keep procrastinating to fix. But my concern is my CEL. Im pretty sure that because i dont have an O2 sensor i am running lean, making other-than optimum fuel efficiency. So what would be my most money friendly choice? should i go to a shop and have them put in a port for me so i can have an O2 sensor, should i buy a new header or should i just go ahead and suck it up and buy an SCT. Which brings me to another question: with sct do i have to run 91 or more octane with it? see, im cheap, money is tight and i want to keep the car. thank you for any help.

**only_in_a_domestic** · 06-29-2008, 08:43 PM

**enviousdreamz** · 06-30-2008, 12:27 AM

Quote:

Originally Posted by only_in_a_domestic

sct

ok, great... but would that require me to have to use 91 octane? i need to be able to use just regular unleaded.

**sayin0487** · 06-30-2008, 12:33 AM

im pretty sure you can get an 87 octane tune. i planned on doing a 93 octane tune whenever i get my header.

**QJKXBM** · 06-30-2008, 01:06 AM

you aren't running lean. the secondary and tertitiary o2 sensors you eliminated have only to do with emissions.

**enviousdreamz** · 06-30-2008, 07:19 AM

Quote:

Originally Posted by QJKXBM

you aren't running lean. the secondary and tertitiary o2 sensors you eliminated have only to do with emissions.

crap, sorry, i just noticed that i said lean, i meant rich... but i guess im confused on what exactly the o2 sensor does. so me not having an o2 sensor wont effect my gas mileage or all around performance of the car? i have a 2000 mile trip in a week, then i have to drive back so i would like to have the best mileage possible.

**pitchblack_focus** · 06-30-2008, 01:56 PM

best bet is to get the xcal and 87 tune if you are concerned with gas prices. From what I hear the 87 tune is just to control your mods & FS makes no claims to HP gains with that tune. It will be a secondary tune though so IF gas ever does drop you can put in some 91 reflash and have the HP gains from the 91 tune.

Someone, please correct me if I'm wrong

**Predator** · 06-30-2008, 06:12 PM

you can do an 87 tune. I did this to my car, but I did pick up a few hp. It also picked up 15 ftlbs under 3200, that was very noticible.

**enviousdreamz** · 07-01-2008, 12:15 AM

ok, great. i really appreciate all the help. but just to double check: the lack of having an o2 sensor will not effect my gas consumption?

**n2o Focus** · 07-01-2008, 09:29 AM

Just remember you going to have the check engine light on without a tune, due to the loss of the heat sensors. So if you have something else go wrong that throws a code, you will not notice since the check engine light will already be on. That is one of the main reasons you get tune for the header. Also you shouldnt be running rich, it might smell like that, but you removed the cat so it wont burn off the excess gas not burnt in the combustion chamber.

**enviousdreamz** · 07-01-2008, 02:26 PM

ok, well i plan on getting the car tuned once i get a little more cash in my pocket. i just got back from a deployment in Iraq and i will be getting out of the army soon so i have some pretty big expenses coming up. but a tune for my car is in the future

**arty** · 07-02-2008, 08:35 AM

There is an O2 sensor bung above the collector flange to the flex pipe. The other two O2 sensors need to be turned off in the cpu or weld in bungs and install the sensors in the exhaust pipe. You may still get codes since you likely don't have a Cat Converter. You need an SCT tune to get you back to good running.

**fordblue03** · 07-02-2008, 08:41 AM

Have you noticed that it only costs around $2.30 more for a full tank of premium. That is one reason I still run it. That's one less soda a week for me.

**OmniFocus** · 07-02-2008, 04:49 PM

Personally, I'd remove the header and go back to stock before I paid for a custom 87 octane tune.

It is somewhat counter-intuitive to install performance parts and then tune the car to run on octane-limited fuel.

**fordblue03** · 07-02-2008, 06:23 PM

Good point on the header. I'd have a couple more bolt-ons first, but my tune get better mileage even though I don't have a header.

**super6** · 07-12-2008, 06:16 PM

I have an '07 2.0L with 3 O2 sensors and the Cossie manifold. As Arty said, install the top O2 sensor (closest to the head) to the bung on the collector. It's the one with the light grey connector closest to the header, on my car anyway. It should run better but you'll still have the CEL and less than wonderful performance and mileage. GET THE TUNE! I got the 91 octane with the 87 if gas goes over $10/gal. I was frankly surprised at how much smoother and stronger the car now runs. Randy at FocusSport does nice work.

Welcome home brother.
A deranged old VN vet, hence....
Super6

**arty** · 07-15-2008, 02:32 PM

An exhaust leak near an O2 sensor will read lean because between pulses the exhaust pulls in air and O2 sensor shows lean. It drove us crazy on a dyno test with a very slight leak from a flange near the sensor.

06-29-2008, 07:01 PM	#1
enviousdreamz TEAM Member Join Date: Apr 2004 Location: kansas city, mo ; lakewood, wa Posts: 165	Concerns with my header and lack of an O2 sensor I bought a cosworth header for my car almost 2 years ago and no problems, just a small leak which i keep procrastinating to fix. But my concern is my CEL. Im pretty sure that because i dont have an O2 sensor i am running lean, making other-than optimum fuel efficiency. So what would be my most money friendly choice? should i go to a shop and have them put in a port for me so i can have an O2 sensor, should i buy a new header or should i just go ahead and suck it up and buy an SCT. Which brings me to another question: with sct do i have to run 91 or more octane with it? see, im cheap, money is tight and i want to keep the car. thank you for any help. __________________ 2004 blue zx3 2.3, focus central cold air intake, cosworth header & flex, cosworth BS delete, mbrp catback w/ extra magnaflow muffler/resonator, Xcal2 tuned by FS, kyb agx, steeda springs, 17" steeda asa wheels, painted interior, short throw shifter, pretty pedals Last edited by enviousdreamz : 06-29-2008 at 09:20 PM.

06-29-2008, 08:43 PM	#2
only_in_a_domestic Senior TEAM Member Join Date: Mar 2004 Location: Florida Posts: 1,484	Re: Concerns with my header and lack of an O2 sensor sct __________________ weight reduction= no sig:-)

06-30-2008, 12:33 AM	#4
sayin0487 TEAM Member Join Date: Aug 2007 Location: Titusville, Fl Posts: 791	Re: Concerns with my header and lack of an O2 sensor im pretty sure you can get an 87 octane tune. i planned on doing a 93 octane tune whenever i get my header. __________________ 07 CD Silver ST with SAP, 2.5" Trubendz exhaust, FS Cool-flo intake, COSWORTH BSD, OBX header, CFM Dogbone mount, CFM 67mm throttle body, CFM STS, Eibach Pro-Kit, 93 octane tune thanks to focussport and the XCAL2 159whp/151wtq 15.431 @ 89.28 mph 1/4 mile -George-

06-30-2008, 01:06 AM	#5
QJKXBM Junior Member Join Date: Feb 2008 Posts: 73	Re: Concerns with my header and lack of an O2 sensor you aren't running lean. the secondary and tertitiary o2 sensors you eliminated have only to do with emissions.

06-30-2008, 01:56 PM	#7
pitchblack_focus Senior TEAM Member Join Date: Aug 2003 Location: roaming Ok Posts: 1,336	Re: Concerns with my header and lack of an O2 sensor best bet is to get the xcal and 87 tune if you are concerned with gas prices. From what I hear the 87 tune is just to control your mods & FS makes no claims to HP gains with that tune. It will be a secondary tune though so IF gas ever does drop you can put in some 91 reflash and have the HP gains from the 91 tune. Someone, please correct me if I'm wrong

06-30-2008, 06:12 PM	#8
Predator TEAM Member Join Date: Dec 2003 Posts: 789	Re: Concerns with my header and lack of an O2 sensor you can do an 87 tune. I did this to my car, but I did pick up a few hp. It also picked up 15 ftlbs under 3200, that was very noticible. __________________ (.)(.)

07-01-2008, 12:15 AM	#9
enviousdreamz TEAM Member Join Date: Apr 2004 Location: kansas city, mo ; lakewood, wa Posts: 165	Re: Concerns with my header and lack of an O2 sensor ok, great. i really appreciate all the help. but just to double check: the lack of having an o2 sensor will not effect my gas consumption? __________________ 2004 blue zx3 2.3, focus central cold air intake, cosworth header & flex, cosworth BS delete, mbrp catback w/ extra magnaflow muffler/resonator, Xcal2 tuned by FS, kyb agx, steeda springs, 17" steeda asa wheels, painted interior, short throw shifter, pretty pedals

07-01-2008, 09:29 AM	#10
n2o Focus TEAM Member Join Date: Jun 2007 Location: Wildomar, CA Posts: 201	Re: Concerns with my header and lack of an O2 sensor Just remember you going to have the check engine light on without a tune, due to the loss of the heat sensors. So if you have something else go wrong that throws a code, you will not notice since the check engine light will already be on. That is one of the main reasons you get tune for the header. Also you shouldnt be running rich, it might smell like that, but you removed the cat so it wont burn off the excess gas not burnt in the combustion chamber. __________________ Who Rides The Short Bus?

07-01-2008, 02:26 PM	#11
enviousdreamz TEAM Member Join Date: Apr 2004 Location: kansas city, mo ; lakewood, wa Posts: 165	Re: Concerns with my header and lack of an O2 sensor ok, well i plan on getting the car tuned once i get a little more cash in my pocket. i just got back from a deployment in Iraq and i will be getting out of the army soon so i have some pretty big expenses coming up. but a tune for my car is in the future __________________ 2004 blue zx3 2.3, focus central cold air intake, cosworth header & flex, cosworth BS delete, mbrp catback w/ extra magnaflow muffler/resonator, Xcal2 tuned by FS, kyb agx, steeda springs, 17" steeda asa wheels, painted interior, short throw shifter, pretty pedals

07-02-2008, 08:35 AM	#12
arty TEAM Member Join Date: Dec 2001 Location: Cleveland, OH Posts: 454	Re: Concerns with my header and lack of an O2 sensor There is an O2 sensor bung above the collector flange to the flex pipe. The other two O2 sensors need to be turned off in the cpu or weld in bungs and install the sensors in the exhaust pipe. You may still get codes since you likely don't have a Cat Converter. You need an SCT tune to get you back to good running. __________________ Comp Orange Coswagon /Torsen and 4.06 gear, alum. flywheel /Centerforce. 2.3L/ 11.6 pistons, 39lb. inj. Eagle rods, Stage 2 Cosworth cams on ported street head with the Cosworth Intake and exhaust.

07-02-2008, 08:41 AM	#13
fordblue03 TEAM Member Join Date: Jan 2007 Location: Clarksville, TN Posts: 829	Re: Concerns with my header and lack of an O2 sensor Have you noticed that it only costs around $2.30 more for a full tank of premium. That is one reason I still run it. That's one less soda a week for me. __________________ 2003 LX, 2.3L, ATX, Arizona Biege sedan. -FocusSport front strut-bar -SCT tune by FocusSport -Eibach Sportline Springs -FocusSport CAI w/factory splashguard -LCR Front Camber plates -FocusSport Catback Exhaust -SPC Rear Upper Camber arms -Red Prothane Bushings (full kit) -28.6mm Steeda rear sway -24mm H&R front sway

07-02-2008, 04:49 PM	#14
OmniFocus Moderator Join Date: Jul 2001 Location: Mowin' down the cones. (CA) Posts: 25,677	Re: Concerns with my header and lack of an O2 sensor Personally, I'd remove the header and go back to stock before I paid for a custom 87 octane tune. It is somewhat counter-intuitive to install performance parts and then tune the car to run on octane-limited fuel. __________________ Vacuum Vulture Racing: We put the "rad" in scrub radius, and the "ack" in ackerman.

07-02-2008, 06:23 PM	#15
fordblue03 TEAM Member Join Date: Jan 2007 Location: Clarksville, TN Posts: 829	Re: Concerns with my header and lack of an O2 sensor Good point on the header. I'd have a couple more bolt-ons first, but my tune get better mileage even though I don't have a header. __________________ 2003 LX, 2.3L, ATX, Arizona Biege sedan. -FocusSport front strut-bar -SCT tune by FocusSport -Eibach Sportline Springs -FocusSport CAI w/factory splashguard -LCR Front Camber plates -FocusSport Catback Exhaust -SPC Rear Upper Camber arms -Red Prothane Bushings (full kit) -28.6mm Steeda rear sway -24mm H&R front sway

07-12-2008, 06:16 PM	#16
super6 TEAM Member Join Date: Apr 2007 Posts: 131	Re: Concerns with my header and lack of an O2 sensor I have an '07 2.0L with 3 O2 sensors and the Cossie manifold. As Arty said, install the top O2 sensor (closest to the head) to the bung on the collector. It's the one with the light grey connector closest to the header, on my car anyway. It should run better but you'll still have the CEL and less than wonderful performance and mileage. GET THE TUNE! I got the 91 octane with the 87 if gas goes over $10/gal. I was frankly surprised at how much smoother and stronger the car now runs. Randy at FocusSport does nice work. Welcome home brother. A deranged old VN vet, hence.... Super6

07-15-2008, 02:32 PM	#17
arty TEAM Member Join Date: Dec 2001 Location: Cleveland, OH Posts: 454	Re: Concerns with my header and lack of an O2 sensor An exhaust leak near an O2 sensor will read lean because between pulses the exhaust pulls in air and O2 sensor shows lean. It drove us crazy on a dyno test with a very slight leak from a flange near the sensor. __________________ Comp Orange Coswagon /Torsen and 4.06 gear, alum. flywheel /Centerforce. 2.3L/ 11.6 pistons, 39lb. inj. Eagle rods, Stage 2 Cosworth cams on ported street head with the Cosworth Intake and exhaust.

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