Rx300 Awd Tune-up Questions

[artbuc]

Wow! Just discovered this site and I'm luvin' it!

Regarding my 99 RX300 AWD w/ 58K miles:

1. This forum indicates chronic problem with carbon in intake manifold. What is the best procedure to clean? SK perf says "motorvac" but I am not familiar with that term.

2. Is there a way to replace rear spark plugs without removing intake manifold?

3. I like to change fuel filters at 60k but that job looks like a mess according to my shop manual. Shop manual also says certain parts are not re-usable, eg mounting gasket and o-rings. If I do this job, should I follow shop manual or attempt to re-use gaskets and 0-rings? Can I buy an aftermarket filter or should I buy Lexus? Do I need to replace fuel pump inlet filter while I'm in there?

This car has been fine except for slight hesitation when first pressing down on accelerator.

[artbuc]

Ok. I've done my homework as I should have before I made my first post. I now know what motorvac is; how to clean my MAF, IAC and TB; how to change the back spark plugs; the many causes for RX300 hesitation; pros/cons of K&N filters and how to modify the cold air intake. All great stuff!

I was not able to find the answers to my fuel filter questions. I did find a couple expert opinions which said my fuel filter almost never needs to be changed so maybe I should just chill on that one and not worry about replacing it at 58K as preventative maintenance.

However, if someone has replaced their 1999 RX300 fuel filter, please let me know if you have any installation tips. Thanks.

[wwest]

First, you must be my age or older if you still believe that fuel filters need to be changed out on a routine basis. The last time I did that the car had a carburator. Simply not needed in today's world, gasoline is filtered right at the pump.

Ditto for spark plugs, your engine ECU will give a diagnostic indication in the event of a consistent misfire. With modern day solid state direct ignition and spark plug technology you won't need to change or clean plugs for at least 100k miles.

Cold air intakes and K&N are useless.

K&N will often result in "premature" contamination of the MAF/IAT due to the oil wicking off the filer element and into the airstream. OEM air filters are typically 90% efficient, so the K&N can only offer a 10% improvement and that ONLY at WOT and max RPM.

Before investing in a "cold air intake" you might want to measure, in real time, the OAT versus the air temperature right at the IAT section of the MAF. You will be surprised to find that they are virtually equal.

Unless you have a cold air intake design that actually chills the incoming airlfow using something like a peltier device or devices.

Your time would be much better spent using a resistance to modify the IAT signal to indicate a false "cold" signal with moderate or high throttle application and the torque converter lockup clutch disengaged.

[mh6]

Hey WWEST, would like to hear more about the modificationed above.

[lsrxlex]

Ok. I've done my homework as I should have before I made my first post. I now know what motorvac is; how to clean my MAF, IAC and TB; how to change the back spark plugs; the many causes for RX300 hesitation; pros/cons of K&N filters and how to modify the cold air intake. All great stuff!

I was not able to find the answers to my fuel filter questions. I did find a couple expert opinions which said my fuel filter almost never needs to be changed so maybe I should just chill on that one and not worry about replacing it at 58K as preventative maintenance.

However, if someone has replaced their 1999 RX300 fuel filter, please let me know if you have any installation tips. Thanks.

←

Artbuc,

Could you show me how to clean my AIC or where to look for info.

I have a 1999 RX300 with 98k miles.

Thanks

[dcmacg811]

Question on MOTORVAC versus BG Products flush (BK44K).... Are both about the same in removing carbon from the induction system? For 98ES300 getting ready for 90k maintenance, I looked into availability of the MOTORVAC in the eastside seattle area. No one does it in my immediate area, BUT some said they use the BG Products cleaning system to decarbonize the induction system and it works wonders. So, is it better to travel a little, through Seattle traffic, to get the MOTORVAC cleaning or is the local BG Product flush just as good?

Search has turned up people claiming the BG44K product is good and that is used as part of the BG cleaning process. Both cost about the same (~$130). But it seems that the rage is all for the MOTORVAC process.

[artbuc]

Isrlex, the IACV is right under the No.1 Throttle Body (closest to the firewall). I haven't worked on mine yet, but I would say the easiest way to remove the IACV would be to first remove the Throttle Body itself. Pretty straightforward job although it does involve disconnecting a couple coolant hoses.

You can find motorvac info at www.motorvac.com. If this looks too expensive/elaborate for you or you can't find a nearby dealer, other posters said they just used a throttle body cleaner and toothbrush. This is what I plan to do. I just removed my MAF expecting to find it dirty but it was clean as a whistle. So, I'm not in a rush to clean the IACV and/or Throttle Body.

[artbuc]

wwest, yes I am a little older. 56 to be exact. I am a retired engineer who loves to tinker so it doesn't take very much encouragement for me to tear into anything.

I am brand new to this forum and I want to thank-you very much for taking the time to give me such a thoughtful and complete response.

Most people think I'm nuts about car maintenance, especially when I tell them I replace brake fluid every two years. But, guess what? I usually drive my cars 150-175 k and I have never had a caliper failure.

[StrykerPro]

Ok. I've done my homework as I should have before I made my first post. I now know what motorvac is; how to clean my MAF, IAC and TB; how to change the back spark plugs; the many causes for RX300 hesitation; pros/cons of K&N filters and how to modify the cold air intake. All great stuff!

I was not able to find the answers to my fuel filter questions. I did find a couple expert opinions which said my fuel filter almost never needs to be changed so maybe I should just chill on that one and not worry about replacing it at 58K as preventative maintenance.

However, if someone has replaced their 1999 RX300 fuel filter, please let me know if you have any installation tips. Thanks.

artbuc,

So how do you get to the rear plugs? I got the middle one but can't figure the other ones.

Thanks!

[artbuc]

Do a search on this RX300 forum using keyword "sparkplug". Thread will give some info and link to ClubLexus which has a very good, detailed explanation. Good-luck.