Rep Power: 0

I have d17A swapped into an ES1 2001 civic LX 4dr Sedan. I am in the process of fixing my exhaust because my girlfriend backing my muffler into a curb and it shoved it all forward breaking my welds and kinking my downpipe and resonator.
SO I am ordering a LX catback kit, and of course will modify myself to suck it up into the car and cut off some slack from the hangers.
My big question is, putting on a aftermarket steel header, and a test pipe below, if i can find one that is.
Can I just pl ug my 02 sensor into the header, or can I just plug the hole.
In the past my 95 d16y I did this, plugging the holes, and it began to bog and act like it wanted to die, assuming due to the lean nature of fuel it was recieving with a plugged 02 hole.
I am honestly stumped and the internet has been no help the last few days. I read triz's breakdown of lx/dx and ex and I just dont get it. Im ordering a d17A standard header pry megan racing. and I am searching for a downpipe or test pipe with the minor bend kink at the end to connect to said header
my questions still lie on the 02... i was gonna just plug it into the new header and see how it runs and visa versa, but I know doing this for long period of time can cause real damage to the internals.
SO please any honest real direct anwers would be great. my cars been on stands for a week and i really would love to go for a drive without it being uinbolted at the resonator and all the sherrifs staring me down XD lmao

 
Rep Power: 511

You have 2 O2 sensors in the OEM exhaust mani/cat assembly
First one is pre-cat, and that will read the exhaust gases leaving the head, and will be an input into air fuel ratio. Thread that directly into the exhaust manifold. You mess with this one, you'll get erratic AFRs and the car will likely run like crap.
Second one is post cat. This one monitors catalyst efficiency. If it reads something it doesn't like (e.g. you go catless), your car is gonna throw a P0420 code, catalyst system under efficiency threshold. If you go catless or aftermarket cat, the best way to avoid a check engine light is a mechanical O2 simulator (I'll discuss this below).

So.. you mentioned swapping in a header for a D17A, which, to my understanding, should be the same as a D17A2 -- the EX exhaust setup. If it isn't, then the rest of this post will be all for naught. lol
Here's a comparison of the two exhaust systems, via a nice little doodle I did waaaayyy back when

Your OEM D17A1 LX/DX setup is on the bottom, and the D17A2 EX setup (and presumably the D17A) is on top. The axle-back portions are identical, and everything upstream of that is different. The D17A1 exhaust manifold reaches a bit further downstream, connects to a longer B-pipe (a.k.a. mid-pipe), then connects to the axle back. The D17A2 has a much shorter exhaust manifold (header), that goes into a separate downpipe that houses the catalytic converter, then to a much shorter B-pipe, then to the axle back.

Why am I explaining all this? The biggest "hurdle" will be the O2 sensor placement (to which your post wants to address). The pre-cat O2 sensor in the D17A2 (and presumably D17A) exhaust is much further downstream, and the post cat is even further (it's physically located just about directly below the shifter assembly). Splicing wires hasn't had much luck with the D17 engines, since sensor choice is a really, really finicky thing with these engines. If it's universal, forget about it. It'll throw a code. If it's not OEM, you got like a 50/50 shot if it'll like it. More expensive OEM? It'll love it. O2 sensor extension harness are a thing, and likely the best course of action to take to get them to reach.

Now, onto the "to plug the O2 sensor bung or plug the sensor into the hole" question. We already addressed the pre-cat one. Plug that sucker directly into the pre-cat bung and call it a day. The post-cat, however, especially if you go catless, won't like it, and your car will illuminate a nice orange light on your dash. It won't affect performance, so if you don't mind the light and you don't need emissions testing, plug it straight into the pipe and call it a day. However, if you hate orange lights on your dash and need all those lights to clear to pass emissions, a mechanical O2 simulator is where it's at. I can personally attest that a mechanical O2 simulator passes OBD emissions testing (at least here in Clark County, Nevada). We don't require visual inspection for yearly check ups. Basically, it's a spark plug non-fouler screwed into the O2 sensor bung, then you screw the O2 sensor into that. It pulls the sensing portion of the O2 sensor out of the exhaust stream to trick your ECU into thinking that all is happy with regards to hippy emissions requirements. Here's a link on the forum of how to make that mechanical O2 simulator. It'll cost you a whopping $5 at AutoZone. Packaging will be different since that thread is now 16 years old, but that part number in the top left corner still works. I did it 2 years ago on my friend's Odyssey.

Now..... you mentioned an LX catback with an EX header. This kinda poses a couple problems. The EX header has zero O2 sensor bungs, since the cat is in the downpipe, and the LX catback will have zero O2 sensor bungs, as well, since the cat is integrated into the OEM exhaust manifold. The only way to alleviate this with this setup is to have a muffler shop weld in a couple of random O2 sensor bungs probably 18-24" apart along the front portion of the cat back, then O2 sensor extension harnesses to let them reach.

An alternative solution is to buy the aforementioned EX header, then mate it to an EX catted or catless downpipe, then to an EX (sedan) cat-back. Or go full on custom with whatever muffler the exhaust/muffler shop has to offer (or you bring in)

A third alternative is to find an LX header, catted or not, then mate that to your aforementioned LX catback. That'll have your O2 sensor bungs, and just do the mechanical O2 simulator on the 2nd one. If you buy a legit DX/LX cat-back, the mid-pipe should have that little kink at the end to mate to a D17A1 header.

hope this helps!

edit 1: proofreading, bc I suck sometimes.

edit 2: I should note that, once upon a time, I found a long 18mm spark plug non-fouler that fit the O2 sensor just fine, no drilling involved. It was also like $3-4. I have not seen them since. It was legit the length of 2 of the short ones (pictured in the DIY guide) screwed into each other.

edit 3: I suck a lot sometimes. Another alternative added


__________________

I would also like to go on record and apologize if this all sounds really remedial or like I'm talking down at you. That is not my intention. My intention is to spread knowledge, and to explain it so that people of every level of knowledge looking at this thread in the future with similar questions will be able to understand this without having to revive a long since dead thread.

 
Rep Power: 0

wow that was informative! I can't say I fully understand but holy crap if I didn't just learn 30 things XD
So my cars a 01 civic LX sedan, the Es1 d17a1, B ut when I got it for a daily to begin with it was 368k motor and trans. clogged cat, (header/cat), and was burning oil. so i got 700 dollar jdm cali d17A swap with 53k and kept the original trans which is STILL going strong besides the input shaft bearing grinding around lol.
So the motor is the vtec solenoid, oil compression regulator over seas model. lol. its a great motor i get like almost 40 per gallon lol, it even runs royal purple and when you check the oil its still practically fresh. I've only put MAYBE 6k on it. if that. But as said the exhaust got messed up all the way to the downpipe. the downpipe which is a long test pipe bent, along with my bend pipe, and my resonator broke the welds and kinked. So i ordered a pro tuning replacement as that is what I assume it was, nothing special but it sounded good and deep, not raspy or rattley. my friends said you can barely hear it unless you got over 4k-5k rpm.
I have a 02-06 type s 6 speed transmisson, harness, header, radiato, k-tuned fuel rails and -10 40ft of hose and filter. i have ep3 subframe and tons more, and some to buy.
But the goal is by summer is over, I am going to either K20z1/z3 Swap it, Or Most likely K24A swap it. I have billet k tuned cabled shifter like i cant even remember I've purchased so much of the list.
My friend did the swap in his 01 2 door and it is a masterpiece. I plan to shave bay, tuck and all. Time consuming and lots of work. But I Plan for it to be a daily and a IFO or show car with my friends crew.

I appreciate your comment and the very informational detail!!!! Huge help! I can not say it enough!

I do think my plan is to just leave my practically brand new catalytic header on there and put the "semi" bent downpipe back on because I can NOT find one that fits "LX" only ex, so im kinda curious if a ex test pipe would do the trick but idk, most sites are discontined or out of stock for the down pipes.
But atm imm just leave it as is, put the new bend, resonator, and muffler/axleback on and Finish purchasing my parts for the K swap.
If you have any other idea for the time being I am all ears!!

 
Rep Power: 511

Glad you learned something. lol. I've been around for.. ever.. (aug 2003), and I initially joined this forum as an 18 year old with an EM2. I know a few things. So much so that they randomly slapped an admin sticker on my account one day. I saw one of my mods creeping on this thread and he prolly said, "pfft, josh got it." lol. Sounds like you're getting stupidly good bang for buck out of your investment. The 7thgen got a lot of hate by the tuning world, but man, I had fun dicking around on this platform.

So, just touching on the K24 swap. Great plan, by the way. Most people that put a K24 in the ES1 did a K20 head because you'll kinda get the best of both worlds: low end torque of the K24 and the high flow of the K20. Also, space considerations. If I remember correctly, the K24 is 4cm taller than the K20, and you already have to trim the hood skeleton to fit a K20 PS pump. K20A would be the move, as it's a JDM DC5-R engine. I think it was Hondata that proved a K20C1 (2017+ FK8 Civic Type R engine) will physically fit in the EM2 (and thus ES1) engine bay, so that'd be a stupidly fun swap. Nothing like a 305bhp OEM turbo 2.0L under the hood. Dunno how compatible the DC5 tranny is though. That, and there are so much incorporated into the FK8 ECU. Sounds like you have a rough plan out for your ES1 though. I'd love to see your progress as you get closer to your end goal.

Hell, in that case, since you're only able to find a D17A2 catback... Grab you a cheap D17A2 catless downpipe and have a muffler shop chop it down and weld in the flange to mate with the cat you have. Either that or just a straight up custom pipe to mate the mani/cat with the cat-back system. I'm assuming the current exhaust manifold you're rocking is a D17A1 exhaust manifold with an integrated cat, yes? If so, then yeah, it'll probably be the best course of action. Cheap out on that exhaust since you're gonna have to change or mod it when you K swap.

 
Rep Power: 0

Yeah My D17 is awesome, I have a buddy with a EG and one with a VX hatch, one of them has a b20 high comp thats his pride and joy as a show car and I can actually stay half a car length up to him, he was awestruck. My vtec solenoid isn't hooked up obviously going from a non motor to a vtec motor, I dont have ecu and what not to wire it up. SO its no, and when i told him that he was like theres absolutely no way. lol
Yeah the k24A is a dime a dozen, so I f igured getting one and swapping out to a six speed es1 with a k24a would be a neck breaker at a low range state wide car show! I know I don't plan to be slammed. Im at factory atm and my cars low low on oemspectrums. But I do plan to get maxspeedingrods or even godspeeds. after i do the swap and all cause the subframe and im unsure if i wanna do the five lug conversion at the same time or later on, its not necessary, but if i go with the k24a and make it work I feel its gonna be needed with that much torque, 4 lug wont wanna hang on lol. If i do find a z1 or z3 online between now and march imma order it. long as its under 2k after that i question if its really worth it. lol
I am certainly not a skilled mechanic hobbiest and enthusiast to learn if anything.
Yeah I have the mani/cat, then a 3 inch bend on the downpipe straight back to the bend connected to the resonator pipe and the axle back/muffler. so idk i think imma cheap it like ya said and keep it as is with the protuning cheap replacement i got and tough it out till i gotta pull the motor trans an all and start sanding lol
funny my names Josh too. Imma toss some pics on here not too explanitory but sort of.

 
Rep Power: 0

 
Rep Power: 0

pic of 02 there one down to the right where you can see the wire.
pic of exhausts you can see left one is new and its 3 inches longer, and pic of downpipe you can see bend.
you can see the bends and kinks in all of them after being back into a solid curb to a dead stop.
at first thought my engine shifted but it runs perfect so checked exhaust cause sputtering and smelling exhaust and sure neough all gaskets and it weldsbroke and seperated

 
Rep Power: 0

 
Rep Power: 0

That sucks... Hopefully you get to fix/replace yours soon