Good afternoon, there is some fantastic info on here, and I think I have read all I can and still have the hood up.

2009 RX350, wife drove it home, parked it in the garage, no issues. 275,000 KMS on it. Regular service. Next day goes to leave, cranks, won't fire, just cranks. Odd. So I pushed gas pedal and it eventually fired, engine shook, smelled lean, stalled out after 30 seconds. Wont fire back up. Seems like fuel issue. No problem. Only code the car would throw was "random misfire, Cylinder 1,3,5,6,7" Now for all them to fail at once seems once again...Odd.

Pulled back seats, checked fuel pressure, 44 PSI under cranking and steady flow out of pump. Odd. Took off fuel rail, measured under hood, 44 psi under crank, no problem. Injectors clicking and getting power. Odd.

Proceeded to remove all fuel out of tank, replace with premium, change MAF, change plugs, changed gas cap, change coil packs, clean throttle body, checked and checked for Vac leaks, eventually took air box off and put 2 PSI on manifold, held like a rock. Check fuel pump resistor, .32 OHMS, has continuity. Changed fuel pump relay, changed AF relay. Still, cranks but wont fire until I step on the gas and then, rough idle for 30 seconds, then stalls out. Smells like its running lean in the garage. Only code "random cylinder misfire"

I'm out of ideas at this point. She wont give up her secret. Any thoughts or direction at this point would be outstanding before I have to get it towed to dealer. Help?

 

Not to panic you, but 4 cylinders misfiring and rough idle to eventual stall while idling is how my 2008 RX350 behaved after it broke a valve spring, and had 0 compression in one cylinder (because of the resulting dropped valve). This of course messes up the whole bank, since the ECU looks at the AF sensor for a bank at a time.

Next steps:

1) Scan the short and long term fuel trims
2) Compression test

 

Good call. I'll check compression and update.

 

The other thing that comes to mind is a large vacuum leak, like a torn hose. If you are doing a compression test, then you may have to remove intake manifold anyway to get at the rear plugs, so stare hard at all the pipes and seals and stuff. No mice chewing through pipes?

Fuel trims are easy to get without work, and if one bank is complete opposite reading of the other bank, or the trims are maxed, it is a clue.

BTW, how to you "smell lean"? I can smell rich, just wondering...

 

Thanks for the assistance so far.

My terminology may be wrong on the smell I guess...The RX makes a strange odor and the exhaust chuggs while the engine runs rough.

I've taken the intake manifold off a few times to check behind there and do plugs, that back bolt on the left really is no fun at all. With it all in tact I rigged up 2.5" PVC into the airbox connection and pressure tested all the piping and manifold. Took off random hoses that has pressure, put them back on and soaped and listened. No leaks.

Bought compression tester today, I'll get the front 3 cylinders done quick, the back 3 slow.

 

All plugs should be out as you do the compression test...

 

And that is why this place rules. Thank you.

 

Cylinder 5 has zero compression. Frick.

 

Wow, I had same issue, fixed it in my garage. Next step, drop the subframe, don't bother mucking about with the engine in the car, nothing you can fix with it in there

My DIY: https://www.clublexus.com/forums/rx-...ve-spring.html

There are some very detailed step by step guides for all the detail of the sub frame drop, google 2GR-FE etc. , like this:
You have a fun spring break coming up! Once engine is out, not hard work. G