Hello, guys. I need some help. I just bought an 2008 at 103k miles, and going through everything to identify what needs to be replaced. I removed a spark plug and saw that it looked just like one in the photo. It had some oil stain on the threads but didn't look bad at all and didn't seem like the electrode was worn. My question is, this plug isn't the original that came with the car, correct? Thanks.

 

Iridium plugs came standard and have long life. The photo is an iridium plug. I believe Lexus recommends changing at 50k. I changed mine at 59k on my 2013 and I could have waited longer. IMHO if yours look good, hold off on spending the money. Do inspect the foam inserts for oil and shine a light in there too. Leaking valve covers are a possibility even with low miles.

 

Just read up on these plugs a little more and it seems there are a lot of fake plugs for sale all over. The car doesn't feel like it idles as smoothly as it should. I will clean the mass air flow sensors and throttle body first. If the idling doesn't improve, I will probably replace the plugs from Lexus and see what will happen.

Do you guys have any other suggestions in regards to improving the idling?

 

What exact model/year do you have?

 

It's 08 LWB with air suspensions.

 

Those are correct plugs for a XF40

 

I'd find out first if there is actually a problem with the idle or not. Not to say you are wrong but I think I'd invest in a diagnosis from the Lexus dealer, since there are several things that can affect idle. And sometimes parts you'd never suspect can affect it (my dad had an old Dodge truck that wouldn't idle after we replaced the engine, so we took it in to a shop; ultimately the tech traced the problem to the ignition switch! I figured the wear in the switch affected voltage to the engine electrical, if you jiggled the key just so the engine would idle flawlessly. If you turned off and restarted the engine, the bad idle was back again etc.)

If you get the diagnosis I'd also ask the tech to check your engine mounts. Because if one or more engine mounts are broken it's possible that is what you are feeling through the driver's seat.
You've got the right idea for the cleaning of the throttle body and that's where I would start, along with everything else that is easy and cheap to do.

 

What is your normal motor RPM, once it's at operating temp? Any codes thru an OBD scan?

 

Thank you for the suggestion. Appreciate it.

 

I will hook up a scanner to see where exactly it idles when it’s at operating temperature. A test that I did was when the engine was warm and I turned on the fan, the smoothness or lack there of didn’t change.

 

Yep, this is a huge problem with both Amazon and eBay. If you do end up replacing plugs, stick to something like RockAuto, AutoZone, etc., some large retailer that is ordering product directly from authorized distributors.

 

If you're new to the LS, there have been many posts here about idling issues. Many of them are "normal" unfortunately.

 

Take a look at "Exhibit B" in this video:

 

I've had good luck with Amazon plugs. Ordered from Amazon not one of the other sellers. No issues.

 

These are with 147k miles on them. Put in at 120k and changed at 267k. 2012 ls460 l AWD. No codes.