Hey all im new here and new to the Honda world.

Anyways I recently bought a 2003 accord coupe with the k24a4 engine and manual transmission, nice car but im having problems. I bought the car from the previous owner who said it needed a head gasket.. no biggy right?! So i get the car home and proceed to tear the car apart, turns out that the head was in pretty rough shape so i get it sent out to the machine shop. They ended up pressure testing it and it passed, so i got them to replace all the exhaust valve guides as they were pretty loose, all new valve seals, everything cleaned up and a valve job done as well as having it decked. Should pretty much be as good as new as far as the head goes. So i get head back on with a new oem head gasket as well as new bolts torqued properly. Fire it up and lots of white smoke at idle and on throttle. Which is weird to me because before all the work was done it was clearly blue smoke, so my oil burning issue seems to be resolved. I knew the cat had to be in pretty rough shape after all the oil it has burned so i took it out and hollowed it out and it runs a lot smoother but still lots of white smoke and clearly water coming out of the exhaust but it doesnt smell sweet like burning coolant normally would.

When the engine was apart i looked at all the cylinders and everything looked good, like new and still had all crosshatching. No visible cracks on the sleeves or block but thats kindof what im leaning towards.

Compression test was as followed
1- 190psi
2- 190psi
3- 190psi
4- 160psi

i pressure tested the cooling system and besides my upper rad hose that was leaking it held 14psi of pressure for a while and slowly leaked off but cant figure out where.
The car has a cel for p1157 which is the upstream o2 sensor but i figure its unrelated.

Does anyone have any ideas as to what could be the cause of my issue?

 

I have a 2005 Accord LX - Same issue, I haven't replace the valve guide seals yet but from researching online and youtube, I've pretty much gathered that the white smoke is oil burning because of a faulty oil ring/s on the piston due to a manufacture defect. Over time, engine wear and usually - accelerated engine wear due to consuming oil at ungodly rates... just makes it even worse...

Grab some Marvel Mystery Oil and pop out your spark plugs and dump the contents of 1 can into all 4 spark plug holes, let it sit over night , Crank the engine without the plugs in it to get all that mysterious magic oil past your failed o2 sensor, which is Very much related and through your freshly hollowed out catalytic converter, (Which In my opinion was not the best idea mainly because the Ecu is programmed to USE IT, so your fuel trims will never be right and the thing might just be smoking very bad because its running rich af.

The smoke from the oil will kill your o2 sensors (depending on how long its gone on)
I would install a cat because 1 its not helping your situation and 2 your gonna have to get the emissions done on it (Eventually...) and yes, they will find out because readings..

also Replace the flex hose (exhaust pipe from the downpipe to the CAT , they fail and will cause fresh air to get sucked into the exhaust (good ol venturi effect. ) and throw off your fuel trims,,,

Catalytic Converters should theoretically last as long at the precious metals are still physically inside / on the honey comb material they as far as I know they don't lose anything in the process, its just their actual presence in the exhaust system that Catalyzes the Reaction. (I'm no chemist so please correct me if I am wrong.. I do know cats are pretty forgiving tho..) they usually just burn off anything Like oil from smoke in the exhaust.