500$accord

I recently bought a 96 accord. It was sitting for a long time before I got it. I have been doing maintenance on it and am at a point where it seems to drive OK, but has a OBDII code P0420. Cat and Oxygen sensors are probably original. ( Car has 152K on odometer )
Before I spend more $$ I thought that someone might have a similar problem with a noise that I orignally thought was valve tapping, but it is not coming from the front of the engine. I adjusted the vavles when doing the timing belt. Is it possibly an exhaust leak and where is this most likely located? It is a 2.2L VTec.
Previous engine codes were EGR related and lean fuel mixture. Those have not come back after burning though stale gas and cleaning EGR ports on intake. I have put about 120 miles on car with new tank of gas. Thanks!!

nspec_Cd5

when the motor is cold, take off the heat shield off of the exhaust manifold.
Then turn ur motor on and feel around where the gaskets are, see if u can feel air coming out of either b/w the head and the header, or the header and the downpipe. U'll have around 15-20 seconds before the header heats up.

if its not coming out of there, then take it to a muffler shop. ask them to see if there's anything wrong w/ the exhaust and they should check for free adn they'll check the whole bottom part for u.

500$accord

Gonna give the exhaust a look tomorrow and I will get back to you on leaks. Thanks for the post.

500$accord

Just took off the heat shield this morning and couldn't find any issues with cracks or gasket leaks on the exhaust manifold. I have to admit by the time I tore the sheild off in the driveway my fingers were pretty numb so feeling for leaks didn't work. Maybe some kind of smoke test would work. The noise wasnt easy to locate either. It kind of comes from teh overall engine block area and quiets down when the car warms up.

Other questions.

Is there a good rust penetrating spray to get off exhaust bolts. I broke two of three getting off the heat sheld on the manifold. Dont' want to break any more...

Is there a problem, other than safety of running for a while with the heat sheild off?

m735is

What weight oil are you using and what the temp outside?
Have you adjusted the valves recently?

PB Blaster is the best rusty nut buster I've found so far.

I think one of the functions of the heat shield is to keep water from directly splashing on the hot manifolds, crack, I would replace as soon as possible.

Line7

The heat shield is so that your engine bay doesnt get as hot. Its no problem to drive the car w/out the heat shield. The tapping is probably your fuel injectors. I wouldnt worry about it since you said you did the valve adjustment.

500$accord

I am going to try and isolate the source of the noise tonight. as much as there is tapping noise that may be cold valves and fuel injectors, there is still a lower frequency noise that a diesel sounds like. I hope it is nothing internal to the engine that has gone wrong.
Since I just got the car, I can't say anything for prexisting problems or even how it was driven/cared for. I am putting my hopes in the general consensus that Honda powertrains are very durable.
Still holding out hope that this is an exhaust leak... I will try to get a better read for the source of the noise with the car on ramps. Thanks for all the posts.

strykernyc

anything with emission is under the warranty for the 96 accord. go get ur free tune up, exhaust,cat and o2 sensors and anything else but BUT I think the warranty is until 150k so u might want to check with ur dealer and maybe roll back some miles.

mahilig77

Go to Autozone or Advance Auto and run the OBD. I'm sure it will give you the codes of what's not working. I am guessing the noise could be due to faulty anti-knock sensor. Fuel injectors also make tapping noises. I have a 92 Accord EX w/ 247K miles w/ tapping valve noise when starting cold then disappear when it warms up. I just learned to live w/ it.

500$accord

I checked around with the knock sensor and didn't see anything listed at several auto parts places online. Is it possible that the 96 accord VTEC does not have a knock sensor?