Hey Everyone,

Sorry for the long post but I wanted to provide all the details so that maybe someone from here can help me figure out this problem I am having. First off I have a 2007 Lexus LS 460 with 149,000 miles on it. I've owned the car since January this year and haven't had a problem with it except for an oil leak from the fuel pumps and valve covers. About a month ago I replaced the fuel pump gaskets along with the spark plugs, and valve cover gaskets. After the replacement the car ran great until a few days later I started noticing a ping/knock under light load around 2000rpm. Once I get past the acceleration the ping/knock goes away or I just don't hear it because of the wind noise.

A little while after the first knock my check engine light came on with the codes p0174 and p0025. I pulled the codes and saw that p0025 was for the camshaft timing bank 2 (retarded). After doing a little research here and online I came to the conclusion that it's probably my VVT solenoid. I bought a new one and replaced it (PITA to get it out), had the oil changed and cleared the codes. Codes stayed off for a while and the knocking went away for a day but came back. Both codes just recently popped back up and I noticed while driving one day that my acceleration was delayed. This lasted on my trip to the airport but hasn't happened since.

I took the car to an independent Lexus shop out here in Atlanta and they couldn't find the cause of the ping/knock or why the codes are being thrown off. They said that it would involve removing the valve covers and they specialize in those engines. They said my best bet would be to take it to the dealer ship as it could be accuators or the timing chains.

If anyone could point me in the right direction as far as things that could cause this I would greatly appreciate it.

Cliffnotes:

• Changed Fuel pump gaskets, valve cover gaskets, and spark plugs, then had a knock/ping under light load 200rpm.
• Car rides perfectly fine outside of the knock/ping. Did have one day where accerlation was delayed and the car struggled to move.
• Codes p0025 and p0174 pop up. Changed bank 2 (passenger side) VVT solenoid but knock/ping still persists
• Independent shop can't find cause.

 

I like to guess....

Did you remove all the small orings on the bottom of the valve cover gasket? They should be removed and set in place on the engine in their respective locations before installing the valve cover ( or replace them with new orings). Having one or more falling out of place can cause lower oil pressure in other parts of the engine. There is a possibility the lower oil pressure could cause a ping / knock. I ended up doing my valve covers twice to verify the o rings were correct.

I'm not familiar with the vvt solenoid. I'd be curious to know if it uses oil pressure somehow to regulate itself? Maybe someone will chime in that knows.

It might be helpful to check if you have an abnormal amount of miss fires in one or more cylinders. Techstream records the number of miss fires for each cylinder. That might narrow it down to a bad spark plug or something of that nature. Codes ( cel) are not always thrown for miss fires if they are not consistent. Hopefully it's something of that nature.

 

Thanks for the reply @miket000 I never noticed any small o-rings just the valve cover gaskets. Every video I've watched of someone replacing the valve cover gaskets I've never seen the o-rings. Do you happen to have pictures of them and their location?

 

Here is a thread with some pictures. I seem to recall a different thread with more pictures and part numbers but I can't find it.

The seals tend to stick to the valve cover. They can be pealed off easily. Before assembly I added some grease to each one for insurance when I set them in their groove on the engine. It sucks to do the job twice but you probably should verify they are in place or better yet replace them.

https://www.clublexus.com/forums/ls-...ent-ls460.html