Hi Everyone,
This past week, I decided to tackle the replacement of the spark plugs and coils on my 2008 Lexus RX350. I only have 80,000 miles on the original plugs but I've noticed a decrease in my gas mileage since new and thought that new plugs and coils might help. I don't know if my gas mileage has improved as I haven't driven the car much this week, but I've noticed a significant improvement in how peppy the car now feels. I guess over time, any reduction in "peppiness" is not that noticeable, but I'm very happy with how good it now feels.

I purchased all the plugs, coils, intake manifold gaskets and throttle body gaskets on Amazon. I went with original equipment parts (Toyota) and probably saved about 60% over dealer costs. I read all the forum posts on doing the spark plug changes and watched the various YouTube videos as well. The video from the Car Carenut Channel was superb. I downloaded it onto my tablet and watched the video while I was working on the car. I noticed a few things that I'm sure others have come across doing this work.

First of all, it's not that difficult; just time consuming. The hardest part was removing the L bracket on the passenger side behind the intake manifold. There are two bolts on the bracket; one at the back attached to the firewall and one attached to the manifold. The video suggests using a 12mm socket with an extension to remove the back bolt. I didn't have one so I purchased one locally. Unfortunately not all swivel sockets are made the same. The one that is used in the video is considerably more compact than the one I purchased. This is important as the bolt is on an angle and the socket needs to be firmly on the bolt and still allow for an extension to be attached so that the bolt can be loosened with a ratchet. My swivel socket would not give me the angles I needed. So I decided to go for the 12mm bolt attached to the intake manifold. Surprisingly this wasn't that difficult to remove. I used a combination 12 mm wrench about 6 inches long and used the open face end on the bolt. Again by putting the wrench on the bolt at the right angle (you just need to do this by feel), I was able to loosen the bolt fairly quickly.

When reassembling the intake manifold, I continually dropped the L bracket bolt as my fingers are just not nimble enough. Learned a few new words and was amazed at how the bolt could disappear into the bowels of the engine. Looking at several of the forum postings, I came across one that suggested making a V cut on the bracket by the bolt hole. This allows the bolt to be put loosely on the manifold and then the manifold can be slid over top of the bolt. Very simple solution and easy to do. Then all I had to do was to tighten the bolt which again was easy once you saw how it all went together.

The only other area that created some difficulty was the removal of the wiring clips for the back coils. On the video, the mechanic makes it look so easy. Just use a pick and click click click and they're off. The problem that you may run into (and I did) is that the wiring clips have become brittle so when you lift the tab, it breaks off. It's important that the wiring clips are locked in place so you should replace the broken clips or fasten them in a way that they won't work their way off the coils. I had ordered a replacement set of clips on Aliexpress 4pin Toyota Lexus Camry Corolla Rav4 Highlander connector Denso Ignition Coil Plug connector 90980 11885|Connectors| - AliExpress and was able to replace the broken ones. Again this is not a difficult job, just time consuming as accessing the rear coil clips is difficult. Take your time and all will be well. One other suggestion is to look at the front coil clips and replace one of them so that you understand what you are doing. It's so much easier to do the front ones.

Replacing the spark plugs and coils isn't really that difficult once you've done it once, but unless you plan to hang on to your car for another 100K, you probably won't need to do it again. I hope that my comments will help someone else doing this work. I really appreciated all the previous forum entries that certainly helped me.

Bob

 

Good tips. Thanks.
Yeah, the Car Care Nut makes good Toyota videos. I'll be replacing my plugs this Winter.
I think I'll go on ebay now to find a used 12mm swivel socket, Made in America, of course.

 

Excellent tip for the brittle connectors. I'll be doing this for my 200,000 mile service.