Originally Posted by vmichelle

I've been a bit busy, but here's my most recent update...

Let me start off by saying that this task is one that I would NOT recommend for most CL members or even general DIY'ers...it was interesting, but the end is near and my car is about a week off from being back to herself (if not better).

This is a general listing of what I have done to get to the head:
- removed all of the fuel rails, intake, valve covers, exhaust manifold
- set the engine to TDC and marked the cams and chains
- removed the cams. While I was slacking off the timing chain to remove the cams I noticed that one of my timing chain guides had a broken seat between the guide and the tensioner - I suspect this is from the Lexus tech who did the valve spring recall...so that needs replacing
- removed the cam surround
- removed the head bolts in sequence and *gently* removed the head with some choice words and a little blood
(note that I did not removed the front timing chain cover, but I decided to replace the water pump since I'm in there)
- Inspected cylinder heads and walls (they were all good)

Once all of this was done I took the head to the machine shop. They called back shortly after to tell me that the valve seals are all perfect at 18 psi. From here I gave them the go ahead to take apart the whole head...I refused to accept that this wasn't the issue. Several hours of worrying that I did all this work for nothing, the machine shop finally called me back. Both intake valves on cylinder 5 had severely worn valve guides (to quote the shop, "razor sharp") and worn valve stems. Currently they're replacing the valve stems, guides, and seals and I should have the head back Wednesday.

For all of the work on the head I've been quoted between $500-600. In addition, I've ordered a top end seal kit from Lexus for $568, which will help me replace all of the seals I've had to open up in this process.

At the end of the day, we're not really sure what caused the part failure but I'm glad we've at least figured it all out.

I've also got some pictures of the internals of the engine that I'll try and post later for anyone who is interested.

Originally Posted by mattevo

looks like I might have the same issue in cylinder 1, great read

Originally Posted by 2013FSport

Step #1 compression test.
Step #2 leak down test to advise you of top or bottom end. The top can be fixed in frame. The bottom end is pull the engine. Or more likely, replace the engine do to parts and labor cost.

Edit - As one can see from reading this thread P030(1 - 6) are only telling us cylinder # didn't accelerate the crankshaft like the others as calculated by ECM. It is up to us to find the cause.

Lets us know if you have any questions.

Originally Posted by mattevo

Called lexus they said $210 plus tax for diagnostics, do you think it’s worth going and get it done? I’m not sure how far they go in depth to diagnose the problem or they just plug in the computer? Unless they will do compression and leak down test. I appreciate the help! Need my daily back on the road.

Originally Posted by 2013FSport

What have you done so far? Most parts stores will scan ECM for free. What's the history, miles, service, work done so far?

250 350?

Originally Posted by mattevo

2008 lexus is350

I changed the spark plug and coil, and I even switched with cylinder 3. So I’m getting misfire cylinder 1 p0301. Prior to that I had the code for bank 2 other side I believe catalytic converter. Had engine check light. Then I put some cataclean and disappeared. That code has not returned only missfire and p0301. I’m not sure what’s next steps to take, just take it to lexus, I don’t think they will do compression or leak down, car has 190,000 miles I don’t want to pay for test and they just tell me car is old need new engine and trade in. What do you think?