Also: when I saw the data on the scan tool, I noticed that the front 02 sensor and the rear 02 sensor were fluctuating very similarly, back and forth a lot like they were following each other. from .68 to .69 to .71. Is that normal?
According to P0420.com, a fluctuating rear 02 sensor means the sensor is bad…I really hope not, I don’t want to get under this car again.
Maybe if I’m lucky, the cat leaking between the gaskets on the exhaust pipe?
Good news: I had my dad hold a rag over the exhaust pipe and I noticed some stuff was still fizzling through the exhaust manifold. I tightened down all the bolts and the leak is no more. Not that I think it’s the reason for the P0420 code or if it was even affecting my gas mileage at all.(least the gasket won’t burn out again. Small victory)
There could be a leak on the lower exhaust before the converter. one of the crossbars that holds the exhaust pipe to the car is really really rusty where it’s hanging on. For all I know there could be a leak there. I’ve been wanting to get a stainless steel exhaust for some time, I kind of hope it’s leaking!
Anybody ever have a stainless steel exhaust? Anything I should look out for know before I buy one?
The OEM exhaust is stainless steel. The brackets might not be though. We still have the original exhaust on out 97 and not a spot of rust yet.
Well, I was recently working on my car and I noticed that where I thought I fixed the leak on the manifold gasket, it’s black. I’m going to replace the manifold and see if that does anything, I can get one at the junk yard for $15.
I also looked at my 02 sensors more closely and noticed that the front one volts is going from .025, to .125 up to .625 varying quite a bit and the rear one ranges from .6 to .7 volts. That’s pretty steady, I suppose that’s normal and they are operating fine.
The last 02 sensor I had followed the front sensor up and down all the way from .2 to 6. I’m pretty sure that sensor was the culprit for my now P0420 code, But I guess once the damage is done it’s done. The good news is that while may be polluting a little bit, if the small variations in voltage are an indication, than least it won’t get clogged up and kill my engine. Which is what I was really worried about.
O2 sensors are supposed to rapidly change voltage reflecting responding to the conditions. Its when they get tired and changes slowly or not at all that they need to be changed.
The rear sensor is supposed to change more slowly than the front one.
Well, I was putting a new bolt on my front right bumper today and I found a bolt lodged between the undercarriage in my car. I went looking for what was missing under the hood and I noticed my air filter was missing one of it’s bolts. It was one of the corner bolts so it might have been letting oxygen in and creating a vacuum. Here’s hoping this fixes something…
Here’s some belated pictures of what my cat and exhaust system looks like.
This second picture I’m not sure what it is. But where the bar hugs it to the body of the frame it looks super-rusty, I wonder if it may be leaking from there? Also where do I pick up dye or something to detect exhaust leaks?
The bar is your sway bar. You have a lot of rust under there so I suspect that the cat has been changed in hte past with one that was not made with stainless steel.
Interesting. I thought it was pretty rusty too and was wondering why it was so rusty.
What do you make of all the rust in the 2nd picture? On that thing that comes before the muffler on the exhaust. Is that the resonator?
Well, I think I’m going to get the car up on ramps and follow the exhaust from the downpipes back to the gasket on the catalytic converter. All the rust under there I wouldn’t be surprised if it oxidized my gasket to dust and it’s leaking there.
In semi-interesting-yet-possibly-irrelevant news, I cleared the code like I usually do, and this time it took 6 days to come back instead of the previous record of five days. I’m hoping the faulty rear 02 sensor is what throwing off the 02 readings and now that it isn’t being overloaded with a rich fuel mixture, it’s starting to do it’s job? (A guy can hope)
I don’t know if these will help, but attached are drawing sof your exhaust system. If the first drawing, the oxygen sensors will be #s 31 and 18. It’s a bit hard to tell, but it looks like the rot in the first photo is in a pllace that would affect your downstream O2 sensor reading.
http://www.thehondapartsstore.com/herson/jsp/catimgs/13s8401_b02.png
Honestly, from the looks of the photos it may be time for a whole new exhaust system. Otherwise you’ll be chasing rot forever.
If you want to know if your cat is clogged up get a vacuum gauge and learn how to use it. If the directions with the gauge aren’t good, there are excellent directions on the internet.
A vacuum gauge will show you a restricted exhaust, sticking exhaust and a lot more.
that should have been exhaust valves. Don’t know where the edit function went.
Now I found it, its the gear in the upper right. I hate it when they replace words with symbols. How does a gear suggest edit.
Mountain bike, thanks for the diagram. I frequently check out the Honda store to compare prices and use their diagrams(Once I found an OEM distributor for the price of a re-manufactured one at the local parts mega store. Honda actually sells one brand new for $234)
I’m pretty sure it’s leaking there, you’re right, I need a whole new exhaust which bums me out. Last year when I bought the car I replaced a pretty sizable hole in between the muffler and the cat.(not to mention the rust effecting the threads of the 02 sensor I installed. I practically had to re-thread it) The pipe I replaced is the only part of my exhaust that actually looks decent, besides my polished up tail pipe, which is barely holding on to my muffler with rusty flakes falling off it like snow. However, there’s no way I am replacing any of it until I fabricate/find a splash guard for the cat and am able to store my car inside. Otherwise, it’s just a matter of time until it rusts out again.
From the diagram it looks that cat comes apart, is that right? I imagine rust has probably eaten through the gasket right before the cat. The one after it wouldn’t affect the reading nor would the super-rot in the 2nd picture before that cylinder thing, right? If it’s past the cat it’s irrelevant is what I’ve heard.
It comes out of the system by disconnecting the two flange joints fore and aft of the converter. The standard method of doing this is to just cut the bolts. The parts will be so rusted togather that they’re likely to be impossible to seperate. The large heat shield will be part of your floor assembly rather than part of your converter.
As you probably already figured out, the drawing in the first link shows the two different header pipes that were used that year. The rest of the system is common to all versions.
When rust abounds, a cutting wheel is a godsend.