redeye1962

My son has shown a great interest in cars and enjoys working on them so we have been turning wrenches together and learning quite a bit from different forums. This forum has shown us so many things and we are still learning.

Our RX has 150k on it and about time we begin servicing different things beside the oil. We did get the 100k timing belt and spark plugs which included water pump tension pulley etc. We had the o2 sensors replaced a couple of years ago because the lights went on during inspection.

So a few years ago I asked about the transmission fluid and the shop said if I have not changed it by now it should not be changed. The dip stick states the fluid does not need to be changed so I am guessing it is a sealed transmission. I just put a quart of fluid in it because it showed to be low. I realize I am on borrowed time on this but hey............roll the dice.

I am having the plugs changed again because the car does not run so well and a little rough idle. while I am on this sight we learned about the MAF sensor and cleaned it which appeared to work for a while until the computer caught up. We then read about cleaning the throttle body which seemed to work for a while then the computer appeared to make adjustments. We tried to get the idle control valve but the screws were in pretty tight and I did not want to strip them.

Any other ideas of what to do to get this thing running better would be appreciated. It seems to drive like a brick sometimes which is frustrating. The gas mileage is around 19 in the city when I drive and 16 when my wife drives.......................not sure how that happens.

so just a recap on this thing no fluid changes except oil and cleaned some sensors and throttle body.

Thanks in advance.

trhs75

Lots of people on this forum advise against flushing the transmission, but I think all agree the fluid should be drained and refilled -- possibly every 15K? Mileage on our RX's is similar to yours -- disappointing! Maybe your wife is drag racing!

hypervish

Welcome to Club Lexus!

Did you use OEM plugs when you had them replaced at 100k miles? If so, there is no reason to replace them again a mere 50k miles later. These plugs are good for way over 100k miles. In fact, mine looked great at 160k miles.

What RPM does the car idle at? How does it "not run so well"? Lack of power?

You can clean the IACV without taking those screws off, it just won't be as effective. You spray into the hole on the lower part of the throttle body and remove the rubber hose coming out of the IACV. You will see nasty throttle body cleaner come out of there as you spray into the hole.

How does the fluid look? To be honest, I'm surprised it has made it 150k miles without a fluid change. Personally, I would do a drain and fill every 15k miles as mentioned by trhs75.

redeye1962

I was not sure what plugs were replaced as I was wondering if they ever were replaced but they did look good when the person replacing them showed them to me. I went ahead and bought new ones anyway so may as well use them.
The idle is weird, sometimes it will be at 1200 other times 750. I did see a post on how to use the hole on the other side after I posted this and will definitely do that when I get a chance. my son said he sprayed some down the hole when we cleanded the throttle body but not much and we did not have the hose disconnected so I am guessing that is why it smoked for a while when we started the engine.
The fluid is of course dark and smells burnt but the transmission is shifting fine. I always wondered about when to change the fluid as I have heard different miles. I see where folks are changing their steering fluid as well I have heard where the brake fluid should be changed as well.
I forgot to mention the shocks have never been changed. They appear not to show wear by pushing the car down but we do feel every bump in the road. I am looking for new shocks and figure on around 3-4 hundred just for the parts. once that is done I will need to align the front end as it does pull to the left.

kalali

When in doubt do a transmission fluid drain and fill as soon as possible. It takes less than half hour and costs less than $20, just under 4 qts. It'll be the best $ you ever spent.

thomas1

The spark plugs are very important, Did you use NGK or Denso iridium? I hope you did not use Bosch, they will cause misfires, and assortment of problems.

redeye1962

I have heard you should not change the fluid if there are excesive miles on the old fluid as it may ruin the transmission. This is what the shop I take my car to told me as well as other forums. I would figure they would want the money so he may be speaking the truth.

redeye1962

Yes, NGK iridium.
I figure the existing ones already have 50k on them so switching is not such a bad thing.

appsdba

Just speaking from experience, I used Bosch on my 1996 Ford Probe GT V-6, which was a Mazda V-6 that was used on their MX-6. For the first couple weeks, I was enjoying the power response. During week three, my engine started talkin' to me on the freeway . So, lesson learned.....don't use Bosch on a Japanese engine.

redeye1962

just another thing I have noticed for some time. When getting up highway speed there will be a clicking noise from the front passenger side. Normal acceleration there is no noise. Just wondering what this may be. I found someone with a similar issue but there was no solution. I will continue to search but if anyone has an idea let me know.

redeye1962

We thought we would keep track of the gas mileage after some of this work we did. we noticed the city mileage increased to 20 but after a trip where the majority of the ride was highway we also got 20 MPG any idea why we did not get better gas mileage on the hwy? this data was taken from the display and was cleared prior to the trip.

sktn77a

iTrader: (2)

That idle fluctuation suggests you might have a vacuum leak. This would cause rough running and poor gas mileage. I get about 20mpg around town and 21 on the freeway (down from 22/23 when it was new). so, pretty much the same as you.

salimshah

The drag coefficient is pretty bad for RX. So intercity milage can drop if you drive at higher speeds. You can try setting cruise at various speeds and monitor the instantaneous mpg reading on a flat road.

It is the stop (idle with no movement) and gaining speed (accelerating) in city driving that tanks the MPG. In moving traffic (constant speed), city milage as dispalyed by instantaneous MPG display is fairly good.

Salim

redeye1962

That makes me feel a bit better. I was always under the impression the hwy mileage would be significantly better than the city mileage for most cars. It seems after we cleaned the throttle body and MAF the idle and performance improved as well as the gas mileage.

Aegean

These protection oil sprays are used extensively on boat engines and metal parts when you winterize the boat. They do wonders keeping rust off in extremely salty environments. It’s an overkill for a car but good investment.