salimshah

Very counter intuitive, as the pump related problems typically manifest it self at high speed ... I guess they can be masked out by the momentum. Did you run a pressure test and a flow test. I think your problem would have been low pressure.

Any way good to know the problem got solved and thanks a bunch for completing the thread.

Salim

Ymmot

@ Nad ..yes i did see ure post earlier i also thought about the fuelpump myself but the sensors kept throwing the code and all of those parts cost a fortune here n my budget did not allow me to go ahead and just change all possible reasons.

@ Salim nope i didnt run the test i just had fuelpump next on the list but since the price was 350 usd i had that part on hold ..the price on parts here is insane so i had to do step by step..about the highspeed is close to impossibel to test here ..my avarage speed is around 35 km/h traffic is heavy.. infrastructure is a joke so high speed is basicly not possible ..the fastest i been driving here in indo is around 140 km/h and that is only possible in the middle of the night and at a very short stretch so it could have had problems during high speed i would not know

ilanh

Hi Yammot,

I have the same problem for long time, living in HK.
1. so what is the bottom line: fuel pump OR fuel filter?
2. Can you explain exactly what was done related to the fuel pump/filter?
3. what is your km/l fuel consumption now?

thanks,

Ymmot

@ ilanh

I changed the filter and the pump ..problem is less but i still feel it during rain season but not as much as b4 ..my avg now is 6.7 km pr liter not impressing but decent compare the traffic, stuck in traffic a lot means ofcourse low mileage, let me know how it ends up u might find some other issue i didnt adress

Australian

Open up your air box and with a compressor air gun blow at your air box ( air flow meter) this gets grit in it and will get stuck. This is the most common problem with cars it is something mechanics recognize right away but gives them a huge excuse to pressure test your engine or just say they did and go through all the irrelevant trouble shooting list that they never actually do because they already know what it is. Before you EVER take your car to the mechanic with this problem open up your airbox and clean it out. It is rarely the fuel filter etc but they will usually sting you for that too.

Ymmot

@ Australien ...i did that as the first thing ..it did not fix the issue ....i did measure on it with a digi meter as well and accoriding to specs form that test it should be working ..i will admit i never changed it since it was within specs ... i recon its the air flow sensor u are refering too wich is located on top of the tube connecting airfilter to injection module

ilanh

for me the fuel consumption is 4.5 km/L driving mainly in HK island
still not able to solve the problem, is yours RX300 AWD?

Ymmot

Nope mine is a front whell drive

mathewd23

Hi Lemex, I am a novice and started working on my 2000 Lexus RX300 after getting dumped by dealer and local mechanics. But I wanted to take this opportunity to thank you and Salim for the effort and time you guys have taken to help people like us who really dont know much about cars and at least be sure not to be taken for a ride with these astronomical costs. I have the same problem as this guy from Indonesia, I changed my spark plugs, o2 sensor, oil pressure switch and oil pickup strainer, but still the car in park mode has about 750RPM, but after the car warms up and i drive it is ok if it is anywhere above 1000RPM, but if i stop at the traffic light in drive mode, it drops to 500RPM. Is that something to do with the IACV or MAF cleanup.

I had to take the manifold out to replace the VCG and the rear spark plugs, could there be a vaccum leak. if so what is the best option to fix it and and make the car enjoyable to ride.
Thanks - Mathew mathewd23@yahoo.com

Appreciate again Salim and Lexmex

salimshah

Thank you for the kind comments but clearly the things you read here are posted by so many members and every member brings in something of value. Lexmex is a legend who energized RX300 forum and now, as an example, ES owners read the RX300 forum to pick nuggets.

I hope the following helps you understand the problem you are seeing:
ECU gets inputs from all sensors and sends signal to IACV. IACV modulates the extra air (and fuel) that gets to the engine. The IACV cleanup only addresses the modulation of the valve under the influence of the ECU signal.
MAF sensor, vacuum, temperature etc provide the input to the ECU. You need some one to verify that these signals are at the right value or have them checked independently.

Salim

mathewd23

Thanks Salim, but i think this test can only be conducted by the dealer. Is there any other names i can look to conduct these tests.

So here is the summary. I started my car this morning, totally cold and the RPM was at 1100 in P mode, the car warmed up and it went down to about 750 or so, Drove the car it runs fine when the temp guage is mdway, but when it is fully warm and if i stop at any stop light or traffic light in D mode, it goes to 500RPM and i feel little vibration on the steering.

2 days back i took the car on a long drive and was driving at 65 to 70 mph. I seen the RPM stay constantly at 3000 RPM, is that common ? but at 70 mph if i take the leg off the accelerator it immediatety starts slowing down, what could be the problem. BTW this car was sitting in my garage for 3 months without driving due to oil leakage 1st from front Valve cover and fixed that, then it started leaking from the front cam seal after replacing a faulty oil sending unit. and I fixed that too So could the car sitting idle for 3 months be the problems to all this

Again thank you for all your advice and suggestions.

salimshah

500 rpm idle is within spec. <== ps ... I dont think any shop will try to mess with idle. Too many control feed backs. Below 300 is where they may start looking.

Is the CEL on?

How about status of air-filter and spark-plugs?

If the RX has been your vehicle, are you noticing the difference or comparing it with other sedans?

At 60mph [flat road] my engine does about 2250rpm (close guess). 1 mark above the 2k mark.

Salim

Baetke

Salim,
Where did you find the 500rpm idle spec? I know that the correct spec in neutral is 650 to 750 rpm but I haven't been able to find the spec for when it is in Drive. Mine idles at 700 rpm in neutral and 600rpm in D with a noticable vibration that I haven't been able to isolate.
Thanks,
Baetke

salimshah

I will try to find the spec. The exact spec calls for engine warmed up and lights turned on and defroster on and brakes applied etc etc.

I should have stated that my engine idles at 500rpm with a very slight vibration.

Salim

hypervish

Mine idles at 550-650 rpm in drive, with no vibrations though. My uncle's RX is the same way, with almost 400k miles on the clock.