My box of parts from RockAuto arrived and I removed my front tries and brake calipers to change the pads. Hunted in the box for the front pads and checked the order form and found out they were back ordered...only part that didn't ship. I did change the back pads with the new ceramic type pads hopefully to prevent rotor warpage.

Anyway it was 7pm and the sun was setting so I figured I would quickly put the new Bosch Platinum 4 prong spark plugs in. The front plug went in in about 15 minutes. The back ones however are much more challenging.

I would rate this as a 7 on a scale of 1 to 10 (10 most difficult). If you don't have numerous 1/2, 3/8 extensions and adapters to be able to interchangeable use both rackets, you will not be able to do this. You also need to be somewhat skillful and agile with both hands since you need to reach around behind the intake manifold. You also need to be able to work by feel since you have limited vision behind the manifold. I started at 7 and finished about 1.5 hours later, after the sun had set and the bugs came out. Figure it will take you at least an hour but less then two. If you have a tendency to be clumsy and drop screws and tools, do bother trying this since you may loose parts behind the manifold.

Here are some tips that will make it easier to change your plugs:
The front ones are easy to change so these tips are for the back ones.
1. Don't start at sunset like I did. Otherwise you will be getting out flashlights and worklights.
2. You will need 1/4 and 3/8 rackets for the back plugs....you may be able to use the 1/2 racket with limited movement.
3. Remove the cruise control bracket (single bolt) next to the throttle assembly on the right side (facing the engine).
4. Remove the PVC tube on the left side the of the back valve cover. Just give it a tug on both ends and it will slide off the tube and out of the valve cover.
5. There is also an aluminum vertical tube with a rubber hose on it just behind the left end of the back valve cover. I had to push this back about a half inch (push on the steel bracket) towards the firewall.
5. I am right handed.... so therefore remove the right hand side first (facing the engine). I did not have to remove the electrical connector on this spark plug tube. Remove the spark plug tube screw and pull the tube out. Be carefull that you do not loose the rubber gasket on the tubing. I dropped two by accident but found them under the vehicle. I was lucky! Now remove the plus and replace it. Here is when you will need to use your various assortment of extensions. It is a tight fit but it isn't too bad. Carefully install the new plug and tighten it. Do NOT place the tube back in. It would get in your way for the next plug removal.
6. The middle plug needs to have the electrical connector removed. I could not get enough clearance to remove the tube without removing the connector. You should understand how the connector comes off since you may have removed them on the front plugs. Bascially you need to press down on the tab and then pry the connector off by placing a flat screwdriver between the connector and the plug andsimply give it a turn and the connector should pop off. Not too difficult once you get the hang of it. I was able to remove the middle connector plug by accessing it from the left side of the intake manifold. Use a long handle thin blade screwdriver and you should be able to reach the connector and pry it off. I used my right hand to hold the tab down and my left hand to pop off the connector with the screwdriver. Now remove the tube screw and pull out the tube. Make sure you do not loose the rubber gasket on the tube. Change the plug from the right side using rackets and adapters. Do not yet reinstall the tube after you replace the spark plug..
7. Now remove the connector on the back left plug and remove the tube screw. I think I was able to remove the screw from the right side of the intake manifold. The tube will come out but you will have to try different twists and angles since the area is very tight. Once out place the new plug in. Now reinstall the tube and the tube screw (make sure you still have the dust gasket on the tube) and reconnect the electical connector. Make sure it is the correct electrical connector.
8. Reinstall the middle tube and screw and hook up the electrical connector.
9. Reinstall the right spark plug tube with gasket (the electrical connector should still be attached).
10. Hook up the cruise bracket with the cable properly placed in the trough.
11. Put a little water or oil on the PVC cable and it should easily slide back onto the tube behind the intake manifold. Press it down all the way into the valve cover gasket.
12. Place the engine cover back on and your down.
Approximate time 1.5 hours, unless you dropped screws and gaskets!!

I was thinking of keeping the old plugs (85K miles) but trashed them. No way would I ever reinstall a used plugs in this vehicle since they are such a hassle to change.

Next job....timing belt and timing belt pulleys replacement. Received the whole kit from RockAuto. Quality looks good.

Now its time to test out the new Bosch 4 Platinums. I don't expect to feel any difference in peformance or gas mileage since the old plugs were iridium.

 

Many thanks for such a detailed description. I know this will come in handy when the plugs need to be changed. I looked at the front plugs and wondered how much work it would be to change the rear plugs. Your tips are invaluable. Thanks again!

 

Sorry about all the spelling mistakes and run on sentences. The Bosch 4 tip platinum plugs were noticeable when I took the SUV on a drive..... I am not sure why this is a difference but the car ran smoother through the rpms and the shift points changed....possibly due to power and torque changes. I did not have any cylinders misfiring before I put these plugs in but I can definitely notice a slightly different (better) engine reponse. I am glad I used the four tipped plugs!! I may buy a set for my other two cars to see if I feel any difference. They all have single tipped platinums in them. My old plugs in the RX were the original iridium tipped plugs and they all looked good too... www.rockauto.com has original and Bosch plugs for the RX....5% discount if you use the info below... In any case.....buy the best, top of the line plugs since you will not be changing these very often.

* When someone places an order at www.rockauto.com and enters your
discount code in the "How did you hear about us" line of the shopping cart,
he or she will receive an immediate 5% discount on that order.
* The discount code expires on June 15, 2003; so don't wait!

**Each month I see people who put the word "discount" in front of their
code and do not get the discount. Please enter ONLY the discount
code.**

 

.

 

Sorry...I did a cut and paste but must have missed the first paragraph.


* You give this discount code: 32265 to friends, neighbors, relatives,
the guy at the corner garage--anyone you know who works on cars or
trucks.
* When someone places an order at www.rockauto.com and enters your
discount code in the "How did you hear about us" line of the shopping cart,
he or she will receive an immediate 5% discount on that order.
* The discount code expires on June 15, 2003; so don't wait!

 

oh those infamous rear spark plugs!
anyway, jp1200x, excellent job! i tried your way and managed only the driver side one, i guess because my hands are so big or something.
this is what i did today:
remove cosmetic engine cover, lexus sign turns, three hexhead studs in the front, done.
take off air filter cover, air intakes. you'll have to disconnect a vacuum line and a sensor.
remove cruise control bracket from throttle body, remove and set aside cable. you'll notice that you have a sizeable opening to go in and behind the throttle body now (throttle body is the one air intakes go into).
remove three nuts that connect throttle body to the air surge (those are the curved pipes that block access to the rear spark plugs). they are not intake manifold.
reach behind the throttle body and find a black support bracket, looks and feels like a metal pipe, black. trace it to the place where it it attached to the throttle body. there's a 12mm head bolt, remove it. it's a FEMALE CANINE to do, only flat spanner worked for me.
remove, very gently, throttle body off the studs and scoot it forward. now you have a lot of access to the rear spark plugs from the right side.
disconnect, on the left, passenger side, 2 wires and a pcv tube from the air surge. be sure to reconnect pcv tube back or you will have NO BREAKS!!
gently remove throttle body to air surge gasket, it can be easily reused.
now you have reasonable excess to the the rear plugs.
disconnect ignition coil wirers from each coil (flat boxes on top of plugs) and set them aside.
pull coils out and set then aside. i sealed mine immediately with electrician greese.
i used a set up of :14mm spark plug socket, short 3/8 extension ans a swivel socket to wrench adaptor. "swivel" adaptor allows this combination to "snake" into the plug tunnels easy.
remove plugs. mine were in good shape but had signs of tips meltdown.
original ngk iridium tipped plugs are available in autozone or schucks AT MUCH BETTER PRICE. my experience with any four or three tipped plugs is like this - don't waste your hard earned money. no difference. get a k&n air filter instead. that one DOES some difference. besides, you'll never have to buy an air filter again as those are washable and good for another 50K again.
anyway, put new plugs in. use antiseize compound, my friendly advice.
i had to put the middle coil in 1st + attach wires, then the passenger 1, driver one is piece of cake. attach wiring and re-assemble everything. fair warning: bolt on the back of the throttle assembly is a ***** to put back in. don't drop it unless you have replacement ones.
so, clear time is about 45 minutes. now this is what you just did:
lexus of tacoma asked $475 + tax for this job as it takes "four hrs to complete". toyota of renton quoted the same. bloody leaches! my cost - cost of plugs and a lot of cssing but at least i did not let them jip me.
funny enough, it takes about the same time to replace oil and filter the way the toyota ingenuity stuck it under the exhaust manifold without any access from the above, below, or sides. even when removed, there's the gap between manifold and radiator SLIGHTLY NARROWER than the filter itself, to pull the filter out. unless you want to dis-assemble all front end skirts and all that undercarriadge stuff that covers filter from the bottom. so, use royal purple as it lasts for 10K miles and you have to go through this hassle only once a year. napa has it at a very good price.
DO IT YOURSELFERS OF THE WORLD, UNITE! IF A PIMPLED YOUNGSTER AT DEALERSHIP CAN DO IT, YOU CAN DO IT CHEAPER, BETTER, AND HAVE FUN!!

 

Why downgrade from Iridium plugs to Platinum plugs? Iridium can last 120,000 miles while the Platinum can go about 60,000.

I hope it's not one of those "more power", "cleaner burn", "better fuel economy" spark plugs. We all know that's baloney right?

 

flipside909 posted 00 RX has Denso IK20 Dual Tipped Platinum. Even with Iridium, the ground electrode is still made w/ platinum.

 

Same topic was discussed on the Toyota Sienna forums. Thought the references might be useful to the group:
http://www.siennaclub.org/forum/inde...showtopic=5144

-chatrathi

 

Just intalled 6 Torquemasters and took a little bit less time, and I can feel the difference.

Kind of funny...maybe my uncle and I missed it...but despite looking in the giant two volume service manual under ignition, we could only find a description of how to do the front plugs, nothing on the rears.

 

As far as the oil filter is concerned, I went down to the auto parts store and bought an " oil filter socket ". It fits over the end of the filter and has a 3/8" socket on the end to use with a 3/8" rachet and short extension. When used with a short rachet , the filter comes loose rather easily. I use NAPA Gold filters made by WIX. The NAPA Gold filters also have a superior rubber gasket [ Toyota / Lexus uses an o-ring ] to prevent leaks. Independent testing has shown that AC and Wix filters are the best that money can buy !. Fram tested to be the worst !

 

I used the easy method discussed above and removed the throttle body. I had great access to the plugs, as discussed. The only thing I can add is in removing the bolt that's attached to the black tube which is attached to the throttle body. It's somewhat easier to remove with 1/4 drive 12 mm socket wrench with a short 2" extension. You can feel around the back of the throttle body and fit the socket over the bolt head. It's still pretty hard to get back there, my back's killing me.

 

Toyota cars that use Platinum plugs recommend a 100k change frequency, more than 60k.

 

No one is not questioning about interval, it is about type of material and how much of it is used in these OEM plugs. After my old posting I found out the Denso plugs that Lexus uses have center electrode made of Iridium but the ground electrode is indeed made of Platinum. Denso's "power" line of plugs has smaller center electrode (0.4mm vs 0.7mm) that requires less voltage to make a spark, great for performance but have less Iridium to wear off, therefor it lasts only 30K. To make a lasting spark, don't we need better material, AND more of it for BOTH center and ground electrode? To say BOSCH platinum 4 is an automatic downgrade from OEM plugs because of platinum is not 100% accurate since BOSCH has 4 ground electrodes instead of a single Platinum one.
Direct quote from Denso's FAQ
"Q. How long will Iridium Last?
A. Iridium use represents the most significant technological advance in automotive spark plug manufacturing, since platinum was introduced in the early eighties. As vehicle manufacturers produce increasingly complex and efficient automobiles, there is a greater need for long-life plugs that can tolerate leaner fuel mixtures and improved combustion processes. DENSO has responded to this need by developing its Iridium alloy, originally for OE applications. For example, many newer Lexus’ and Toyota models carry an ultra long-life Iridium plug variation (.7mm with platinum tipped ground) that is capable of up to 120,000 miles of service. DENSO Iridium Power plugs, with their .4mm center electrode, have been developed for performance applications. Because gradual wear will “round-off” firing points over time, the concentrated firing power and voltage requirement benefits will be reduced. For this reason, DENSO advises replacement after 30,000 miles."

 

My Torquemasters have 4 prongs and I have only heard once or twice the sound of gas particles popping in the escape...whereas with my last Denso plugs would hear it at the track. My Denso plugs were replaced at Lexus in December 2004 but with bad burning gas...I had to find a better option.