jorge89

I just failed my emissions test on my 94 civic EX. As I was inspecting the car I've found a very small crack right by the O2 sensor on my exhaust manifold. I wanted to remove the manifold to replace it with a new one, but when I was trying to remove the O2 sensor it would not budge. After soaking it with lubricant overnight and using a breaker bar I ended up bending my ratchet and I think the crack might have got slightly longer. Does any one have any suggestions? I don't know how to weld and I don't want to pay some one to do this. Does any one know if there is any way to seal the crack?

95Sedan

Heat up the bung that the 02 sensor goes in with a torch and then get it off using a wrench or other..
Then replace the manifold..
inspection should have nothing to do with the exhaust manifold having a crack in it.

jbpnoman

Except a cracked manifold can cause an O2 sensor to read incorrectly, causing an improper amount of fuel to be fed, causing his car to fail emissions.

OP, get a torch at your local hardware store and heat it up. The flange should be almost red hot. Then it should come out easily. Also, get better tools.

jorge89

Right my HC(ppm) at idle is too high so I'm suspecting the crack on the manifold to be the culprit. I know that ratchet was pretty cheap and too small for that anyways. I don't think that heating the flange would damage my O2 sensor right?

jbpnoman

It may, it may not. Out of every O2 sensor bung I've had to heat (more than a Shaq-sized handful) I've only had one turn out bad afterwards, but it came with this guy's imported motor, so we don't know if it was even good before hitting it with a torch. I have heard of them failing after being torched, but I've never had any reliable, first person experience with a torch causing it to fail.

nealnanoHX

YEah it may damage it but keep in mind that O2 sensors get hot and are design to withstand the heat to a limit. Get a header off ebay and a new O2 sensor a tune up may be a good idea as well if you have not done one in a while, it will help with the HC as well.

jorge89

Are those ebay headers reliable? Have you used them? I was thinking about getting a used stock one from a salvag Yard

delsolintegra

I had the same problem with my 93 del sol si and I went with a $60 ebay header and a new oxygen sensor. Works fine. If you take the exhaust manifold off the engine and work on a bench to remove the oxygen sensor it might be easier.

jorge89

So I just got a used one locally since I need to pass this before the month ends. I'm still having the same issue with too much HC. I just got new spark plugs and I've double checked the gaps on them. I'm going to be trying new spark plug wires too.
There is one thing that is confusing me a bit though. If I have too much HC left that would mean my engine is not burning all the fuel. I've also noticed that my car makes a pinging/knocking sound when I go up hills. Can my engine be detonating too soon and at the same time not be burning all the fuel? btw my car is completely stock except for an intake.