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Stanvandam
To answer a few of your questions. Idle when I first start the car when the outside temp is in the mid 60s is about 1200rpm for a minute or so and slowly drops to 750. That's with all accessories off. When I cleaned the throttle body I had no one to help me, so I laid a chunk of concrete block on the accelerator to make the throttle go wide open. (Ignition on engine off of course)And said a small prayer it didn't roll off while my fingers were in there lol. The rough idle existed before I cleaned the maf. Which is what got me to reading the forums and gave me the idea to clean it and the butterfly flap while I was at it. Idle is no better or worse after. The MAF appears to be reading airflow. It reads about .5 lb/minute at idle and jumps to 2-3 lb/minute with a light blip of the throttle. I'm not used to owning a vehicle which uses a MAF. every car I've had in the past had a map sensor instead which is much less sensitive to vacuum leaks as long as they are before the throttle plate. So you may be on to something with the pcv valve. I guess if it's stuck open it would be no different than having a vacuum hose unhooked. I'm going to try to upload a few pictures here for you guys.
Note all of these were taken with all accessories off, vehicle in neutral with parking brake on, and at full operating temp which was reading between 195 and 200 degrees while I was taking the readings. The cooling fans never kicked on. The graphs are all over a 10 second period of time .
Ignition timing at idle
Maf towards the left is at idle first hump was a blip of the throttle to about 1500rpm let off slightly then biped again to about 2000 rpm
Rpm at idle over a 10 second period left side of the graph shows it fluctuated from 744 to 768rpm during that time.
Just an update. Thank you everyone for the suggestions. I cleaned the idle port on the throttle body which wasnt that dirty (the holes werent plugged but there was some carbon) I replaced the PCV valve, and am currently running 2 cans of b12 Chem tool in a full tank of gas. It's a little strong but I'll cross my fingers the plastic parts hold up. While I was replacing the PCV valve I noticed there's a 90 degree elbow where the vacuum line goes to the gas tank. That elbow slid right out of the 1 inch piece of vacuum line that attaches it to the purge solenoid. So I threw a hose clamp on it. I'll keep you guys posted on the results.
Just an update. Thank you everyone for the suggestions. I cleaned the idle port on the throttle body which wasnt that dirty (the holes werent plugged but there was some carbon) I replaced the PCV valve, and am currently running 2 cans of b12 Chem tool in a full tank of gas. It's a little strong but I'll cross my fingers the plastic parts hold up. While I was replacing the PCV valve I noticed there's a 90 degree elbow where the vacuum line goes to the gas tank. That elbow slid right out of the 1 inch piece of vacuum line that attaches it to the purge solenoid. So I threw a hose clamp on it. I'll keep you guys posted on the results.
I was told by Yami i believe from the ls400 thread, that when cleaning the idle ports you want to remove the cover, and spray a cleaner while the car is running down the holes. I used about a half of a can. You may need someone to keep the rpm up, so the engine won't stall out. Tom57 was correct in the spelling, here was his exact response to a similar problem. Yamae
"Your problem reminds me of the clogged throttle body and the air mix path. The air mix path for a UCF20 is explained here but it's in Japanese"
Thank you for the suggestions. I'll have to get back in there with some throttle body cleaner. Does anyone know the part number for the gasket that goes between the idle port cap and the throttle body l. If I take it back off again I want to replace it.
Ok let down first. I got back in the idle port with some carb cleaner. Skipped the throttle body cleaner and went for the harsh stuff. Made no difference. But I have peace of mind knowing it's clean now.
And the happy news. Problem solved. Thank you again Lavrishevo. I should have listened sooner. I said screw it and replaced the coolant temp sensor. I let the car cool off for 2 hours. Plugged in the code reader and and it showed 138 degrees. Swapped out the sensor. Checked the temp again... 147 degrees. Almost 10 degree increase. And who would have thought 10 degrees would have made such a huge difference. 20 minute job to change it. I urge everyone who's having lack of power or idle issues to listen to all the advice on here and change it. I'm sure it will take a couple of drive cycles to gain the full benefit. But right away there was quite an impressive increase in power at light throttle.
Side note. After I finished the sensor change I let the car idle and checked the temp readings as they came up. Just an FYI to anyone who's curious. From 180 degrees to 200 degrees the teperature gage on the dash stays dead centered. So if it's visibly reading low after warming up your temp sensor needs changed. Thank you again!
Great news! Glad that worked out. I am of the opinion that this sensor should be changed around the first TB/WP job. From what I understand, there is a different sensor for the actual cluster gauge. I always thought that was odd but I am sure Lexus does this for some good reason.
Let us know about your highway mileage too. You can always pull the negative on the battery for 10 seconds for a soft reset.
You know what would be interesting. Has your coolant ever been changed? Do you have a multimeter to perform an electrolysis test on the coolant? I would not be surprised if this may directly affect the sensor and the coolant eating away at the metal itself.
You know, I was trying to confirm this about the temp sender for the cluster and I can't for the 430. I think I am wrong about this. On the LS400 there are 2. But one website said only 92-98. One main ecu sensor and a gauge sender. I can't find a separate sender on the 430. Anyway, let us known if your highway mileage improves. I will call my dealer and see if I can find out about the sender.
Edit: Yeah, forget what I said about the temperature sender. We don't have this. All combined into one sensor.
Is the correct part # 89422-30030 for the temp sensor? (Earlier post before edit in this thread showed a different part #.) Also, if the gauge and ECU are controlled by one sensor in the 430, then if the gauge shows the correct operating temp, how could the ECU be getting the wrong engine temp info from the same sensor?
As my3uzfe mentioned, the gauge did not move between 180 and 200 degrees. Must be the way it's calibrated. As little as 9 degrees off to the ecu can have a large effect on how the engine runs.
I also had a +3 long-term fuel trim on one bank. I also had changed most of my vacuum lines.
I suggest taking a stethoscope and removing the bell end. Put the stethoscope in your ears and slowly drag the open end of the tube around all your vacuum lines.
I found a leak that was so small, seriously the size of a pin hole, but when I fixed it, my long-term fuel trim went back to 0 and my mileage went back up. AND, it had a LOT more power.
The +3 long term fuel trim can only be caused by an air leak.
Really enjoyed reading this thread so far. Great info in here.
I've been experiencing a strange, albeit minor throttle response issue for awhile. I've got techstream setup and am hoping i can take some MAF and TPS measurements with it. I haven't had the chance to try it out yet, so this post may be premature. But hoping I can get some feedback from a couple of you on how I go about it.
I cleaned my TB and MAF awhile back. I made the noob mistake of using my hand to open the butterfly valve when cleaning the TB. Ever since those cleanings I swear I've lost a mile per gallon. And my throttle response when flooring it is weird. I get a little hiccup of sorts before regular power delivery kicks in. And every so often, when starting the car, it sort of shudders for a bit while idling. Not often though. Sort of rarely. But it has happened multiple times. After reading this thread I'm wondering if my MAF or more likely my TPS is out of spec because of the way I went about my cleaning.
How does one go about using techstream to take measurements? Does the car need to be
running? Or just turned on, but motor off? I'm assuming the former, but wanted clarification.
What are the acceptable ranges for the MAF and TPS?
If either is out of spec, can they be re-calibrated? Or is replacement of the part the only fix?
Assuming I can use techstream to look this stuff up, are there any other A/F stuff I should check while I'm looking?
Sorry to piggy back. Looks like the OP got the answer they were looking for though, so thought it was okay to do so.
Alright... I'm digging this post back from the grave because it's the same issue. Only now it's slowly getting worse. And there are new symptoms. Same as before the idle is rough when warm. The car feels like it lacks a little power on slight inclines. And most recently, shifting is becoming rough in the higher gears. (Holding 5th longer shifting rough into 6th) So all of that being said, I've done my share of reading on here and like posted earlier in this thread it sounds like one of the oil control valves for the vvt is on its way out, it just hasn't triggered the MIL yet. all of my symptoms match another post describing how the car runs when they fail. Mine are just less severe. So I have the Toyota part numbers left 153400F010 and right 153300F010. And the Dorman equivalent 917-293 and 917-292 respectively. So I'm prepared to shell out the money to replace them ahead of time 1 to avoid having it fail on a long trip and 2 I want my Lexus to run like a Lexus. While I'm at it I thought I would clean the filter screens for the oil control valves.... where the *@^$*# are they? I've searched and searched and the closest I got was a thread on here for a 98 ls 400 where it's under a cam bearing cap.... under the valve cover. Please for the love of all that is good tell me they weren't dumb enough to design our generation the same way. I'm hoping it's behind a bolt cover near the solenoid. But I need someone with experience to direct me the right way. Thanks for the help.
06-25-15, 06:22 AM
