benjamin24

It might be old carbon burning in your intake and valves after the tune up. I noticed when i sprayed cleaner on mine the RPM would raise...The Ecu apparently takes a while to relearn the right idle and hold constant...a new maf really handled my rough idle.
Maybe get everything right you can, and then let ECU try to relearn for a few days. New OEM parts never go wrong.

Mine is idling at 1.1 still... Im thinking I might need to get the old OEM alternator rebuilt and throw it back in.

try out a new PCV Valve. DENSO MAF as well. Maybe seafoam it. IDK. Atleast you eliminated one problem. I think the throttlebodys on these should be good for a long time and it makes sense its still good. However they are electric with a sensor in them. Everything electric wears down around 150k plus miles. I would replace the throttle body as a last resort. Premium gas is a must, on a battery reset, and also you need to check your air intake infront of the Throttle body for anything wrong. The air intake that is infront of the engine and connects to the airfilter box can get lose.

benjamin24

If you find you need to get a throttle body, buy from Bell Lexus online. Or go to the junkyard and grab one from a car that looks like it was taken care of. Its $800 new. Youre going to have to spend decent money if you dont pull it yourself from junkyard. Most people dont even change their oil or brakes on anything for 30k+ miles.
You might have unreal build up and clogged your PCV valve when you put in the degreaser. I would only put seafoam or air intake cleaner etc but atleast it started. I drove by an Is250 yesterday that was shiny but it tried to keep up with mine and smoke came out the back... Make sure you arent losing coolant into your engine. I think you are right about the throttle being open too much but it does open based off the computer and what the computer tells it. if its open more than it should be, then it thinks it needs more air to keep up with the fuel in the car i believe.

benjamin24

Also did you try the idle reset relearn? Be careful shifting from Park when your RPMS are high. I think you are close to solving your problem

benjamin24

I didnt realize you took off your intake manifold... you should replace that gasket asa it mightbve degraded over time and cant seal, or check for vacuum leaks and reinstall it. Torque all bolts to spec. You need to start from the center bolt then end at the outer bolts.

2013FSport

iTrader: (2)

Jarred, take a close look at the edges of that throttle plate, I'm guessing it has a nick or something in it keeping it from closing all the way. Be careful though as it can cut you. Mind you, a nick will create a corresponding gouge in the perimeter somewhere. If any repairs are attempted, try first with a rounded hard object to fold the brass plate back into place as once you file it, that are can be an air leak.

My 350 only changes RPM when the engine cooling fan kicks on. To a much lesser extent when the AC compressor and fan kick on. This could be because the BCM is telling the ECU to throttle up slightly in preparation for the load being imposed.

As for the person w RPM all over the map, your alternator is likely the cause or a bad connection or a really crappy battery. Put a volt meter on it and watch it.

Also have the battery and alternator load tested.

JaredAU

- I COULD replace the MAF but honestly I don't think thats it. What is your g/sec on idle when at operating temperature and in PARK?
- I drove the car 600km thinking the codes might clear but they stayed, did all the learning it could
- I'd say get a DENSO alternator just because I've heard bad things about aftermarket ones.
- The PCV valve is functioning correctly I've tested it in twice now. Also triple checked the PCV hose and torqued the PCV to spec.
- Did a vacuum test with a vape and I had ZERO leaks so the air intake is solid.

- I've already tried a used TB from ebay and it gave me TB high circuit codes and really screwed with the car so I returned it.
- PCV is fine and not clogged and I don't have unreal buildup as far as I can see, just normal amount.
- The TB being open too much was me referring to the new aftermarket cheapo version I bought. It's got a bigger resting opening than the original denso one.

- Yes I did and I still feel like I'm so far away. I want to do more tests on the alternator. Thanks for the hype though
- I've taken the manifold off three times now and reseated it. the gasket is fine on the TB its not the problem and the intake is down fine - I just performed a smoke test with a vape and there's no leaks what-so-ever that I could see

One more thing Ben, could you please just post one reply and edit it to include future comments if you need at a time? I just would like to keep this thread a little organised with ideas as I'm running low on them as it is.

I honestly think the new aftermarket one is just crappy. Its made to have a bigger opening than the denso for some reason or its just poorly built and they haven't set it right.

None the less I ran a VACUUM LEAK test today
- I did a vape juice test with a vape that blows the fattest clouds (lmfao) and sat there doing it for 30 minutes trying all sorts of ports and blocking off parts of the engine to try and force any kinda vacuum leak to appear but there wasn't a single thing. It would just blow smoke out of the intake at the front. Tried the break booster and the fuel line inlet as thats blocked on the australian version.

WHAT IVE TRIED:

VACCUM LEAK
NEW TB
CONNECTORS
PURGE VALVE
PCV VALVE
INTAKE GASKETS

MY NEXT LEAD - Possible battery fault or alternator fault OR MAF reading over 3.1g/sec constantly??

Ever since I got the car, the interior lights would flicker - only the top 'door opening' ones and rear top not others like dash, radio, other lights. What could this mean?

I've observed their behaviour:

Car is running with door open for rear - Flicker
Car is running with door open + heat on highest + headlights on = Flickering is really really bad
Car is off after just running with door open for rear - Flicker - Possible charged alternator still causing the flicker when car off?
Car is off and hasn't been running - Lights are stable and DO NOT flicker

SEE VIDEO OF ISSUE:
Another guy pointed me to his alternator in this thread: https://www.clublexus.com/forums/is-...l#post11359484
I did his test and let the car run solely off of battery and the car still ran the codes.

The batter voltage is 12.5 V with engine FF
The battery voltage is approx. 14.5 V with engine ON
The battery voltage is approx. 14 V with load (aircon, headlights etc)

From what I've seen these values seem to be spot on and good.
I just think maybe the ALT or battery might be throwing weird current to the IAC and causing a hickup?

I'm going to try a battery from my other car over the weekend and see if I get anywhere.
Alternator seems to have been replaced once but not sure if its aftermarket.

It might be this as the lights have weird behaviour but other than that I'm out of ideas except for the high reading on the MAF.
Could anyone else chime in with their Idle - in park and operating temperature MAF rate in g/sec?

Again, thanks for reading. Much appreciated for any help.

MikeFig82

iTrader: (13)

For the smoke test you need to cap the throttle body. You can put a heavy duty latex glove zip tied. This will inflate the glove like a balloon to show pressure. You just want enough pressure to inflate the glove, and not to cause it to pop off.

Now seeing the voltage number. It seems the alternator is over charging.

On a cold start the voltage readings would be around 14 - 14.3V. Now once warmed up, and with load it should be around 13.7V.

Here's my voltage once warmed up,, and AC, and headlights w/fogs.




Also check for swelling on the battery. Looking down from top view it should not be bulging on the long sides.

JaredAU

Hey Mike, glad to see you again in the thread.
Smoke test - Thanks for this tip! I put the glove on this morning and zip tied it. Couldn't see a single a single strain of smoke through the intake while the glove was almost bursting. Glad that's eliminated, phew.

Battery tests - Just did some tests and here is the result. Made a youtube video too for reference.

Cold start voltage reading - 14.4V
Idle in Park, ACCESSORIES OFF - 14.38 - 14.4v
Idle in Park, HEATER ON FULL, HEADLIGHTS ON, INTERIOR LIGHTS ON - 14.5 - 14.8 V jumping a lot in that range.

As you can see its NOWHERE near your range when under load.
What's interesting is that when load is applied the voltages go UP, should they go down to high 13 low 14 Volts?
BUT with every alternator video I've watched they say 14-15V is pretty much in spec... Which has confused me even more.
Even says it here: https://www.clublexus.com/forums/is-...r-voltage.html
Is it possible that the alternator is just doing weird stuff, How would I explain the interior lights blinking when the car is off, AND when the car is on...

Battery has copper or lead sulfate (blue stuff) which would indicate the overcharging thesis too
Battery is also a 'blemished' battery which really doesn't point to much.

Thanks for any help as always

2013FSport

iTrader: (2)

14.5 to 15V will boil a battery dry. That's not normal and not healthy.

Batteries take current to charge. Voltage only needs to be 13V or so. A battery that when drained, allows the voltage to shoot high is near the end of it's life. Likely on it's way out. The problem is knowing if the alternator voltage regulator is okay. Yours going to 15V seems out of spec.

Again, get both load tested. Something isn't right.
Any chance you have a DMM / multimeter with peak high, peak low freeze frame data? This would allow you to capture how low it goes doing cranking and how high it goes when loads are added/removed.

JaredAU

Hey mate, providing an update on this as I've only had a chance to work on the car today.

I really think its the voltage regulator/alternator, I tested the batteries condition and its 13.56V at 585/650 CCA so its not the best but still fine I believe.

I only have a simple multimeter but I was able to run some tests today and used process of elimination. I basically replicated @Shawnkim 's steps from his thread where he replied thankfully.
Pasted here for convenience.

1. Warm up to operating temperature.
2. Disconnect the negative terminal of the battery
3. Disconnect the alternator positive terminal from alternator (after separation, cover it with gloves so that it does not close to the body)
4. Start after connecting the negative terminal of the battery(Do not go far, it can run for about 10-30 minutes depending on the battery condition. Also, the battery warning light will come on)
5. Check idle. If it returns to normal idle, you have found that there is a problem with the alternator.

I actually did this test a month ago but what happened was that the p0505 code popped up for what I believe was some kinda residual memory still kept in the system so the code never confirmed It was just pending as I think it takes 3 cycles to confirm and store the DTC. So I believed that the test failed and it wasn't my alternator and went about trying to find other reasons.

Doing the test today has pretty much confirmed to me that in fact the alternator is the issue. Let me explain.

Warmed the car up to operating temperature and started it up with the alternator disconnected and just running off of the battery.
The code I believe (that obviously appeared when warming the car connected to the alternator) wasn't cleared before I removed the alternator so it remained as pending in the system. Clearing the code once again with the engine off but alternator disconnected, I ran the car off of BATTERY ONLY for a total of 5 minutes to let the car settle in.
Idle RPM was now 700-800 which I believe is in spec and perfect. With the alternator running it would idle at 900-1000 (Due to the high charge maybe?)
No code appeared after 5 minutes of idle and the flashing interior lights had stopped flashing and remained solid the entire time. (There was a small flicker on ONE light, but it might have been as a result of the engine load across the battery)
I drove the car down the road really quickly and stopped at the local mcdonalds car park for a couple of minutes. Turned the engine off. Let it sit, turned the engine on. Shifted from park to drive and back to park again. All things trying to replicate the code appearing. It didnt.

Its important to note that the MAF rate is down from 3.4g/s to 2.4g/s which is in-line with what you guys were saying was the standard.
TB position is also down from 14.51% to 14.12% which ofc would be letting LESS air in.
I guess the higher voltage caused everything to ramp up??

I accidently shorted the alternator I by placing my wrench on the positive volt while the battery was connected which sparked and turned off the engine. (Bad rookie mistake). The engine wouldnt start for a while and I thought I'd blown a fuse. To my surprise it started again after like 5 minutes of pulling my hair out but this time the alternator clearly wasn't working because, while connected and engine running I would disconnected the negative terminal and the engine cut. Since then the alternator is working again somehow and throwing the same code WHILE CONNECTED. I just put it down to it doing funky **** and best not to worry about wtf actually happened with the short.

TLDR: I'm going to replace the alternator! I feel really stupid when the answer was pretty obvious from the start I'd say with the lights flickering and all.

I called the lexus dealership today for advice and its pretty much cleared up my alternator theory. The previous owner could have fitted a non ECU controlled alternator and that would have caused over voltage issues which then could have lead to faulty readings on the MAF/TB causing the car to throw the code. That or its just a bad alternator in general.
I'm going to fit an aftermarket one with a 3 year warranty and see how I go with it. I will report back here once its done.

Thanks again @2013FSport @MikeFig82 and especially @Shawnkim as well others for your continued help on this.


This is from the freeze frame when the p0505 was thrown. Notice the airflow rate and the throttle position when compared to the photo below. RPM here was 917 also higher.




This is what it reads with the alternator disconnected. Notice the low MAF rate compared to the previous idle rate of 3.5g/s and TB position being more closed.

2013FSport

iTrader: (2)

Dude, what in the actual F kind of test is that???? It does not represent any real world conditions...

Go to parts/tire store and get a real load test done for both components.

GL

JaredAU

Doesn't it eliminate the alternator from the picture thus that's the problem if no codes appear and car runs smoother?

I will go get them load tested tomorrow.

MikeFig82

iTrader: (13)

Yeah just get it load tested. Anyway get the ECU controlled version.

These modern cars have dual mode charging systems.

You can read how Honda's work. I'm sure Toyota's works in a similar fashion.

JaredAU

​​​​​​
Ended up going to a parts store to get a free load test done. They had some old af tester that just printed out a result that was in line with my multi-meter. I asked if they could load test it when I had all my accessories but he told me he 'couldn't do it with that machine' I told him just read it while I turn on all of my stuff and he wouldn't. They were low-key useless and a waste of time.

On the positive note though. I bought a new alternator. Aftermarket with a 3 year warranty.
Installed it over the last two days and also replaced the serpentine belt and guess what? NO MORE CODE.
Interior lights still flicker a little but I'll look into that problem another time.

Car now idles at 700 RPM in park and 600 in drive. Absolutely perfect idle and engine sound and it seems to just be running so much more smoother as I drive it.
I also had a problem with the console cigarette port not powering on a usb hub despite the fact it had voltage running through it and this also fixed that problem too!

The Multi-meter measures 14.2 - steady while the car is running.

Honestly I'm over the moon excited I've fixed this. Over a month later of constant tests and pulling the intake apart etc and I've found it.

Incredible that all this was caused by a slight overcharge by the voltage regulator of the alternator sending more voltage to the circuits of the maf and TB thus causing them to malfunction and also throw codes. (Speculating thats it)
I wanted to thank you guys so much for all the help you've given me over the past month. For that I'm forever grateful and owe you a beer if you're ever over in Australia. @2013FSport @MikeFig82

Also a huge thanks to @Shawnkim for putting me on the alternator trail also. Couldn't of found it without you and saved me thousands of dollars in labour from a mechanic no doubt.


OLD ALTERNATOR freeze frame with code

NEW ALTERNATOR Note: Maf rate and idle RPM

benjamin24

Hey Jared
Glad the Alternator fixed it, I came back today to let everyone know a DENSO alternator fixed mine as well. I had my original DENSO alternator rebuilt at a local shop. It did idle high initally, however i did a few procedures and it went down. I will be making a video on this because you need to idle relearn with the headlight, radio, and ac off after the new alternator goes in and also pull the fuel injector fuses!