2004 Rx330 Spark Plug Replacement

[KBRX330]

Getting ready to replace the spark plugs on my 2004 RX330 as am now at 137,000 miles on the originals. ( they are still running fine and I'm wondering if I should go to 150k?) Has anyone done this? I have a Haynes Manual which states that you need to remove the throttle body and upper intake manifold to access the rear 3 plugs. Looking at the engine I can see no other way. Any tips from those who have done this chore will be greatly appreciated. :)

[code58]

Getting ready to replace the spark plugs on my 2004 RX330 as am now at 137,000 miles on the originals. ( they are still running fine and I'm wondering if I should go to 150k?) Has anyone done this? I have a Haynes Manual which states that you need to remove the throttle body and upper intake manifold to access the rear 3 plugs. Looking at the engine I can see no other way. Any tips from those who have done this chore will be greatly appreciated. :)

Greetings- I changed my DIL's at 97k and was suprised at how good a shape they were in. (99RX300) A true testament to the quality of iridium. I would say if your mileage hasn't dropped off and it runs good, go for it. I'm sure I'll be flamed for that advice.

I did not remove the upper intake manifold but I did remove the throttle body. Just didn't want to go hunting for gaskets. It wasn't easy but it was doable. Don't know if the '04 is any different in that respect (engine compartment) or not but I dought it. Good Luck

[GDixon]

Getting ready to replace the spark plugs on my 2004 RX330 as am now at 137,000 miles on the originals. ( they are still running fine and I'm wondering if I should go to 150k?) Has anyone done this? I have a Haynes Manual which states that you need to remove the throttle body and upper intake manifold to access the rear 3 plugs. Looking at the engine I can see no other way. Any tips from those who have done this chore will be greatly appreciated. :)

The RX spark plug job is so onus that there are many posts and threads on the technique and requirements. Try a search of this site for the information you want. After that information is perused you can decide what you want to do and whether it is worth a trip to a Toyota dealer or independent shop. A Lexus dealer simply wants too much for the job.

[RX in NC]

I replaced the factory Denso iridium plugs in my wife's previous 2000 RX300 at 120,000 miles as called for in the Owners Manual. I had pulled the three front plugs at 90,000 miles just to look at them and was impressed at how well they were holding up. Even at 120,000 miles, the original Denso plugs looked great with only very minimal rounding of the tips. Gas mileage never dropped off and performance (I hesitate using "performance" with any RX) remained the same as it was at 60,000 or 90,000 miles. I changed the plugs primarily because I felt it would help me sell the vehicle which I knew I would do at 130,000 to 135,000 miles. There is no question in my mind that these Denso iridium plugs would have easily run 150,000 miles and probably many more. My wife currently drives a 2004 RX330 that runs these same Denso iridium plugs and if they perform as well as they did in her old RX300, I probably won't change them until at least 150,000 miles. She'll hit 70,000 miles within the week so her factory plugs are probably just now getting broken in. I probably won't even pull the three front plugs to look at them until at least 100,000 miles....

When you do change your plugs, do your research first because the three rear plugs require contortionist skills to get in and out. There are plenty of posts on this forum that you'll find helpful so take the time to search. Because of the placement of the three rear plugs, what should be a 30-minute job always turns into a 2 or 3-hour job even with the right tools. I had to borrow a neighborhood friend of mine with small hands in order to get to, remove, and replace the center rear plug - what a hassle even for him, but he finally got it done. Good thing he happened to be home the day I decided to change the plugs. Be sure your socket wrench set has plenty of extensions and universal joints - you'll need them. Good luck....

[wwest]

I replaced the factory Denso iridium plugs in my wife's previous 2000 RX300 at 120,000 miles as called for in the Owners Manual. I had pulled the three front plugs at 90,000 miles just to look at them and was impressed at how well they were holding up. Even at 120,000 miles, the original Denso plugs looked great with only very minimal rounding of the tips. Gas mileage never dropped off and performance (I hesitate using "performance" with any RX) remained the same as it was at 60,000 or 90,000 miles. I changed the plugs primarily because I felt it would help me sell the vehicle which I knew I would do at 130,000 to 135,000 miles. There is no question in my mind that these Denso iridium plugs would have easily run 150,000 miles and probably many more. My wife currently drives a 2004 RX330 that runs these same Denso iridium plugs and if they perform as well as they did in her old RX300, I probably won't change them until at least 150,000 miles. She'll hit 70,000 miles within the week so her factory plugs are probably just now getting broken in. I probably won't even pull the three front plugs to look at them until at least 100,000 miles....

When you do change your plugs, do your research first because the three rear plugs require contortionist skills to get in and out. There are plenty of posts on this forum that you'll find helpful so take the time to search. Because of the placement of the three rear plugs, what should be a 30-minute job always turns into a 2 or 3-hour job even with the right tools. I had to borrow a neighborhood friend of mine with small hands in order to get to, remove, and replace the center rear plug - what a hassle even for him, but he finally got it done. Good thing he happened to be home the day I decided to change the plugs. Be sure your socket wrench set has plenty of extensions and universal joints - you'll need them. Good luck....

Some "credit" for long lived spark plugs is due to the construction of the plug itslef but mostly its a result of the modern day technological advances.

Coil/plug eliminates a distributor.

Solid state CDI ignition.

ECU ignition timing parametric mapping.

In the olden days the spark had to jump TWO gaps, two gaps in series yet, the one in the distributor cap and the plug itself. Then there was mechanical and/or vacuum DYNAMIC ignition timing modulation within the distributor itself which inadvertently moved the distributor rotor position in relation to the contact for the plug to be fired.

Oftentimes the HV spark would find a shorter path, especially as the HV wiring degraded, and sometimes to a plug wire that was not under compression.

Surprising to me, today, that those ignition point/condensor/distributor systems ever worked at all.

These days it could very well be that your spark plugs NEVER need to be changed for the initial, non-overhaul, life of the engine.

[RX in NC]

I've had friends run regular ol' $2 copper-tipped domestic plugs for more than 100,000 miles in vehicles such as a 1998 Ford Expedition and 1992 Ford Mustang with no adverse effects. There's no question that today's plugs combined with relatively recent engine and ignition technology create a far more harmonious atmosphere for the spark plugs and they'll last much longer compared to the 1960s and 1970s as a result. My 1999 Dodge Ram 5.9-litre V8 requires a specific Champion plug that was less than $2 the last time I changed them (20,000 miles ago). Although the Owners Manual calls for new plugs every 30,000 miles, I feel sure that these regular Champion plugs could easily do 60,000 miles and maybe even 90,000 miles under careful driving conditions. But because I only put around 6,000 miles per year on my truck, I'll probably continue to change the plugs every 30,000 miles. Unless these plugs have gone up drastically in price since the last time I changed them, it's less than $20 to change all 8 of them....

[KBRX330]

Well I spoke to the dealer today and he advised that it is not necessary to remove the TB or Intake manifold but only the engine cover, PCV valve & hose and the throttle cable bracket and I should be able to reach around the back of the engine. He said lots of people call to get the IM & TB gaskets and they advise them of this as that is how they do all of them and there is just enough room to fit a u-joint & wobble extension under the IM to get the center plug. I hope he is not kidding.... :o

[GDixon]

Well I spoke to the dealer today and he advised that it is not necessary to remove the TB or Intake manifold but only the engine cover, PCV valve & hose and the throttle cable bracket and I should be able to reach around the back of the engine. He said lots of people call to get the IM & TB gaskets and they advise them of this as that is how they do all of them and there is just enough room to fit a u-joint & wobble extension under the IM to get the center plug. I hope he is not kidding.... :o

Let us know how it goes. It would be nice to hear some good news about plug changing in the RX.

[code58]

Well I spoke to the dealer today and he advised that it is not necessary to remove the TB or Intake manifold but only the engine cover, PCV valve & hose and the throttle cable bracket and I should be able to reach around the back of the engine. He said lots of people call to get the IM & TB gaskets and they advise them of this as that is how they do all of them and there is just enough room to fit a u-joint & wobble extension under the IM to get the center plug. I hope he is not kidding.... :o

Let us know how it goes. It would be nice to hear some good news about plug changing in the RX.

I already had the T/B off because I was replacing the IAC but was able to reach around the back from both sides- a stretch but I made it. I pulled 1 of the front plugs out today just to see how it looked (replaced them 20k ago) and was amazed that it looked virtually new! I have read that iridium is the hardest metal known to man- I believe it! :o