Exhaust manifold replacement.

[leathermaneod]

Hi all,
I'm new around here and this is my first post. I have a 04 civic LX with 202k. It's an awesome car and I plan on keeping it till the wheels fall off. I'm not a racer or anything, just trying to make it last and keep it maintained. I'm not new to wrenching and try to do everything myself. Anyway I have two issues at the moment. First, I have an exhaust leak. It's either the manifold gasket or the manifold is cracked. So I'm planning to replace it. What sucks is the cat is built in so the darn thing is expensive. I've been reading that I could just get a header w/out cat and use the little o2 sensor adapter on the downstream sensor to fool the pcm and keep from getting codes and still pass emissions. I'm from PA so passing emissions is a must. What I'm wondering is, is that a reliable fix? Can I rely on that setup with fooling the pcm to pass emissions every year? Or should I just bite the bullet and get a header with cat?

Second issue, I've had a code for the fuel tank pressure sensor for over a year now and I'd like to get it fixed but the sensor is over $100 minimum(no it's not a bad gas cap). Is there any way to wire in a resistor and fool the pcm with that? Or do I have to give in and spend the money on that too? I tried messing around with a potentiometer, but I'm no expert with auto wiring and I didn't get anywhere other than a no start in one configuration lol

Any help greatly appreciated!

 

[XpL0d3r]

to ClubCivic!

I would first make sure it's not the gasket, that should be an easy fix if it is. If not, you can do the o2 defouler trick, there's a ton of writeups on how to do so. You can also get an aftermarket header and aftermarket cat -- if it doesn't bolt up you can have a shop modify it. I would also check junkyards and Craigslist for 7th gen (non-EX/Si) exhaust manifolds and maybe pick one up for cheap.

What's the code that you're getting for the tank pressure sensor?

 

[leathermaneod]

to ClubCivic!

I would first make sure it's not the gasket, that should be an easy fix if it is. If not, you can do the o2 defouler trick, there's a ton of writeups on how to do so. You can also get an aftermarket header and aftermarket cat -- if it doesn't bolt up you can have a shop modify it. I would also check junkyards and Craigslist for 7th gen (non-EX/Si) exhaust manifolds and maybe pick one up for cheap.

What's the code that you're getting for the tank pressure sensor?

Thank you!
Will I be able to tell if it's the gasket by just pulling it off and looking for damage? This is an area I'm not yet familiar with....also the problem I will have with that is getting the bolts out of the heatsheild without breaking them off in the head...any tips?

I would probably go with something that will be a bolt on fit or maybe some minor welding/fabbing as I don't like having to rely on shops. I have lots of bad experiences when I let other people work on my stuff...
Is deleteing the cat and fooling the post o2 sensor a long term fix? I have no problem with doing deletes, just don't want something temporary. I'm not sure if I wanna dig through a junkyard either as I've heard cracks in the manifolds are quite common....

I'll have to get the code read again and get back to you. I initially tried to fix that a year or so ago and had three possible sensors based on the code. I replaced the cheaper ones first, but of course, the code kept coming back.
Thanks again!

 

[HeX]

Manifold cracks are easy and obvious to spot. Theyre also easy to have a shop weld the crack, so take off the heat shield and inspect it. A gasket leak should be easy to identify as the leak area will show signs of it, especially if the engine is running. Furthermore, aftermarket manifold/cats are reasonable cheap. Look into all that before going the route of a defouler.

As for the fuel pressure sensor issue, make sure to post the check engine code. Give serious thought to whether or not it makes sense to rig something involved in fuel delivery. Just fix it properly.

FYI, you can buy OEM parts from online dealership sites, such as HondaPartsNow.com, at discounted rates.

 

[leathermaneod]

Manifold cracks are easy and obvious to spot. Theyre also easy to have a shop weld the crack, so take off the heat shield and inspect it. A gasket leak should be easy to identify as the leak area will show signs of it, especially if the engine is running. Furthermore, aftermarket manifold/cats are reasonable cheap. Look into all that before going the route of a defouler.

As for the fuel pressure sensor issue, make sure to post the check engine code. Give serious thought to whether or not it makes sense to rig something involved in fuel delivery. Just fix it properly.

FYI, you can buy OEM parts from online dealership sites, such as HondaPartsNow.com, at discounted rates.

Thanks for the tips! I will definitely look into all this some more as soon as I can. As for the code, it's just an emissions thing, not fuel delivery.

 

[XpL0d3r]

Thank you!
Will I be able to tell if it's the gasket by just pulling it off and looking for damage? This is an area I'm not yet familiar with....also the problem I will have with that is getting the bolts out of the heatsheild without breaking them off in the head...any tips?

It depends. The gasket could be totally shot, or it might just be worn in one area. But if you're going to replace the exhaust manifold, you will definitely want to replace the gasket anyways. As for getting the bolts out, you can try hitting them with a torch to loosen them up. You can also hit it with some liquid wrench or PBblaster to see if that helps.

I would probably go with something that will be a bolt on fit or maybe some minor welding/fabbing as I don't like having to rely on shops. I have lots of bad experiences when I let other people work on my stuff...

Is deleteing the cat and fooling the post o2 sensor a long term fix? I have no problem with doing deletes, just don't want something temporary. I'm not sure if I wanna dig through a junkyard either as I've heard cracks in the manifolds are quite common....

I don't blame you. When it comes to the exhaust, there isn't a whole lot to it. As long as the second o2 sensor gets a cleaner reading than the primary, everything will be "working". The o2 defouler trick really just backs the sensor out from fully being inserted into the exhaust. As such, it sees a cleaner reading, and thinks the catalytic converter is doing its job. It can be a permanent fix, as long as you do it right. Personally though, I would fix it correctly and put the sensor in there.

I'll have to get the code read again and get back to you. I initially tried to fix that a year or so ago and had three possible sensors based on the code. I replaced the cheaper ones first, but of course, the code kept coming back.
Thanks again!

Sounds good!

 

[leathermaneod]

It depends. The gasket could be totally shot, or it might just be worn in one area. But if you're going to replace the exhaust manifold, you will definitely want to replace the gasket anyways. As for getting the bolts out, you can try hitting them with a torch to loosen them up. You can also hit it with some liquid wrench or PBblaster to see if that helps.


I don't blame you. When it comes to the exhaust, there isn't a whole lot to it. As long as the second o2 sensor gets a cleaner reading than the primary, everything will be "working". The o2 defouler trick really just backs the sensor out from fully being inserted into the exhaust. As such, it sees a cleaner reading, and thinks the catalytic converter is doing its job. It can be a permanent fix, as long as you do it right. Personally though, I would fix it correctly and put the sensor in there.



Sounds good!

Ok so I got the code read today. It is P0497. They say it could be the purge solenoid, vent solenoid, or fuel tank pressure sensor. I've already replaced the first two, so I'm assuming the ftp sensor is the only thing left....any thoughts?

 

[leathermaneod]

Well just wanted to update this for anyone who may read it in the future. I finally got around to ordering parts and replacing things. The old exhaust manifold was cracked. That was very apparent as soon as I removed the heat shield. I ordered a new one off ebay for about $120. I also ordered the fuel tank pressure sensor at the same time so I could finally get rid of that pesky check engine light. Well the job when great and I got everything replaced. I also thoroughly cleaned the throttle body and iac valve and the pcv valve while I was under the hood. For the first 100-150 miles everything seemed to be great, but now the check engine light is back with the same code as before, P0497, low purge flow. Any ideas guys? Ive now replaced three stupid evap valves/sensor, two on the charcoal canister, and one at the throttle body, and still having this issue. Has anyone else out there gone through this same thing?

 

[XpL0d3r]

Hmm, take a look at this thread:

http://www.civicforums.com/forums/36-mechanical-problems-vehicle-issues-fix-forum/312813-error-code-p0497-evap-system-low-purge-flow.html

Mentions something about calibrating the ECM.

But, how did you clean the PCV valve? It would be best to replace it rather than clean it.

 

[leathermaneod]

I just took it out, cleaned it with brake cleaner and q tips and made sure it still moves freely. I actually put a new one in, but it made a very loud ticking noise that I didn't like. I had read somewhere else that they should never need to be replaced, just cleaned, so I figured it was fine as long as it moved freely. Do you think I should replace it still? Does it really affect anything? I read somewhere that it might affect oil consumption, so I replace the one in my 06 crv because it uses more oil than I'd like, but I've not had that issues with this car, even though it has 50k more miles lol

I have read that thread, but honestly, it doesn't make any sense to me. From what I understand, the whole evap system does not affect the way the car runs at all. I don't believe it has anything to do with the fuel air mixture, that should be controlled by the upstream o2 sensor. I could be wrong though.
Thanks for the reply btw, all help and suggestions are appreciated!