Rep Power: 0

Hey,

I blew the 1.7 in my '03 Civic and installed a 1.7 Vtec from an '04. The engine is in the car & running but I have some air fuel/02 sensor problems.

#1) I have the non-SI full exhaust on the SI engine, there is one male connection coming from the SI wiring harness towards the front of the engine. I made the assumption that would hook up to the air fuel sensor (or upstream sensor whichever you prefer), but the connection from the SI harness is male and so is the connector for my air fuel sensor.

The male connector coming from the SI harness does connect to the 02 sensor (or downstream).





Connectors in relation to one another :


The air fuel sensor (upstream) on the SI exhaust is going to be closer to the front of the engine, so why won't my air fuel sensor connect to the SI harness ? Obviously you need a male/female..

#2) I can't find the other female connector on the SI wiring harness, I've looked all over the place for it. Of course I didn't look for it before I had installed the engine... that would have been much too easy. Can anyone tell me where it should be ?

I've also been looking for a wiring diagram to confirm that the SI connector at the front of the engine SHOULD be connecting to my air fuel (upstream) sensor. I was tempted to cut the ends off of my air fuel & 02 sensors, switch them around & then connect my air fuel (upstream) to the SI wiring harness.

Thanks in advance for your help !!

 
Rep Power: 517

2003 used an O2 sensor, while 2004-05 used the AF sensor?
Put your 2003 sensor back in it?
(Even though they appear similar, AF sensors and O2 sensors are VERY DIFFERENT. Cannot be swapped.)

Help me out here....I'm in the US and your cars are called different things. And your post is confusing.

Your 03 Civic is a what?
Had the cat up front on the manifold, or under the car?
NOW the cat is where?


Which wire harness did you use?



If you still have the same engine wire harness that the car came with, then the plug SHOULD still be where it used to was....

 
Rep Power: 0

Nope, the '03 and the '04 both have 1 air fuel sensor (which is upstream of the catalytic converter) and both have 1 02 sensor (which is downstream of the catalytic converter).

Our cars aren't called anything different, maybe different terminology as far as parts/components go, but that's more of me being a noob than a difference between Canadian/American cars.

My car is an '03 Civic, which is why I posted in the 7th Gen Civic forum. As I posted (and underlined), I've got my non-SI exhaust bolted up to the SI engine. The non-SI exhaust has the catalytic converter connected/welded to the headers, whereas the SI exhaust seperates the headers from the catalytic converter. On the SI, the catalytic converter is under/behind the engine.

I've got my non-SI exhaust bolted up to the SI engine.

My cat is connected/welded to my headers.

I used the SI wiring harness.

 
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I should have a female AF sensor connection coming off of my SI wiring harness towards the front of the engine - I do not, I have a male connection coming off of the wiring harness.

I should have a male 02 sensor connection coming off of my SI wiring harness towards the rear of the engine - I can't find anything ?

 
Rep Power: 517

03 uses an Oxygen sensor at both the front and the rear. (primary and secondary)
04-05 uses an AF sensor in front and an Oxygen sensor on the rear.

You cannot swap an AF for an O2. The computer cannot use it even if you could get it plugged in.

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The terminology part is just that ........I'm in the US.

For 2003, a USA EX is the same as your Canadian SI up there.

A 2003 SI in the USA is a 3 door hatchback with a 2.0 K engine.

IDK what our LX/DX/HX compares to up there, that's why I was wanting to know about what your car is and where the original cat was on it.

 
Rep Power: 517

Harness for the cat under the car....like the USA EX

The rear sensor connector should be on a small branch coming out of the main engine harness along the passengers side of firewall, near the steering rack. If you changed out the whole harness, it could be caught anywhere along there.

EDIT: If the harness is for an 04-05, the computer for an 03 still can't use the AF sensor. SOMETHING will have to change or be modified