2000 Civic HX Manual Transmission -

A couple months ago I backed into a very low (hence invisible) concrete barrier at 5-10 mph. It made a pretty wretched sound and did some damage to my exhaust pipe, but I don't know how much. The pipe no longer wants to point directly out of its notch in the bumper, instead about 20% of it is obscured by the plastic. It also rattles quite a bit unless I wrap a shop towel around it (which also helps put it back in place).

Around this time (I can't remember if before or after, unfortunately. I realize this information would be useful) I got engine code P1163, which is for an oxygen sensor. I managed to get away with reset it and forget for a while it but now its becoming a problem. Since I first had this car over a year ago I noticed just a little hesitation when accelerating in first gear but it was very minor. Gradually this hesitation seems to have gotten worse. The much bigger problem is that now maybe for 1/3 of my trips the car craps out right at 4000 RPM in every gear. It doesn't stall, just refuses to go past that point. When I turn the car off and start it again the issue may or may not go away. If reset the ECM the light goes back on in correspondence with this problem. The feeling is similar to the hesitation I get in first gear and said hesitation seems to be worse when the 4000 RPM problem is happening - recently I had reset the light and she was really week accelerating in first and when I hit 4000 the light came on and I couldn't get above 4000. There seems to be a correlation here but I'm not 100% sure.

So I definitely have a problem with my exhaust and/or this oxygen sensor. The thing is without better knowledge I have no ability to look at my exhaust system and visually diagnose it because I've never dealt with this kind of thing before. Do I just visually inspect for cracks? The fact that the pipe is askew tells me there might be a bigger problem. I could try to replace the sensor and see if that fixes my problem but the part isn't cheap so I want to proceed thoughtfully. I could take it into a professional but I don't have anyone I trust here and I'm poor so I'd much prefer to try to tackle this myself first. I don't really care about the rattle or appearance of the exhaust system, I just want the engine to work right and it is a safety concern not to be able to reliably go above 4000 RPMS.

I passed emissions a couple weeks ago, if that information helps.

I appreciate any advice you guys might have.

 

P1163 can be caused by a faulty primary O2 sensor or by an exhaust leak. Given the damage to the exhaust system, an exhaust leak would be the first thing to investigate.

1) Remove the header heat shield (cover).
2) Raise the front end on stands, and then remove the splash shield.
3) Inspect the header from above. Post pics.
4) Inspect exhaust pipe A and downstream exhaust pipes from below. Post pics.

 

All of those pipes can be found at the local salvage yard, but you gotta move quick on the pipe that connects to the bottom of the cat converter and the b-pipe. These ****'s will sawzall it all off.

 

Sounds good, I'll post those pics tomorrow or the day after. Thanks!

 

Could this be the problem?

How do I tell how deep this goes?
Here's the rest of the pics:
Exhaust System Album on Google Drive

Lmk if you need me to get back under there and retake any pictures. I tried to cover all the surface area of the exhaust system but I might have missed something. I poked around with a very bright flashlight and didn't see anything. While I was under there I think I might have managed to readjust the end of the tailpipe so that it clears the bumper.

 

Yes
Replace the header/cat unit. Also purchase a new exhaust manifold gasket and lower exhaust pipe gasket. Then go from there.

Hopefully you won't need also to replace the O2 sensors. Soak the threads of the O2 sensor in PB Blaster for a few hours before attempting to remove them with a breaker bar.

Is the muffler pressed against the gas tank? If so, you may need to carefully bend the exhaust hangers to increase the distance between them.

In the near future, you may want to pinpoint the engine oil leak and fix it. Focus on the highest points on the engine where you see oil accumulation.

 

Thanks for all your help. You're all right for a liberal.