hybrid450

I always appreciate your feedback and detailed info.

I already got the fuel additive (Techron Concentrate Plus, heard good reviews of it) and poured it fully to ~65% tank level. Before that, I had also tanked the car with better fuel. BTW, is the additive supposed to clean the port injectors or direct ones in our cars?

Fuel trims didn't change much, maybe the SHORT negatives spike less now (as you saw, before it could spike to even -16, now the max I saw was ~ -12). My LONG B2 is almost always ~2% different than B1, and the max I saw under hard load was ~ +7% (with B1 ~ +5%), after steadying at high speed they are usually +4.6% both, and while normally cruising at lower speeds they usually don't exceed ~ +3% (with B1 sometimes being like -0.3%) and SHORTs jump ~ -5 to +5% when driving steady, and almost always 0% on higher speeds. I don't know when these negative spikes (-12%) happen on shorts, but most likely when engine is kicking in/turning off while driving.

I also made sensors test to make sure they work properly by taking off the oil cap and it seems they work fine - the SHORT trims went high until I put it back on. One thing I noticed was with downstream O2 sensor (O2 B2 S2) which stayed low at constant 0.01V while the B1 sensor was ~0.09V and floating - it was checked on idle after around 5 minutes driving so maybe it wasn't warmed up enough yet, because after some more driving the B2 sensor got alive and shown similar values to the second one, but I had a feeling that B2 works "slower".

I was already driving and wanted to make use of the poured fuel system cleaner at all speeds from driving low and high for some time as I didn't know at what speeds/revs it will "clean" the best. I will now drive slower and shorter until I reach low tank level, and I was also planning to reset the long trims by clearing DTCs (heard it works for some cars) or disconnecting battery for 10mins, and I wanted to see how it will re-adapt after driving with the additive and refueling the car. What do you think? Or better not to re-learn the values? Also after that PCV valve change, I didn't re-learn the values, maybe that would also have some effect because the last time I disconnected the battery was while changing the fuel filter.

What did you mean to do this before changing my oil? Should I change my oil again after running full tank with the fuel additive? It's been changed around 1500 km ago with Amsoil 5w30 SS along with Amsoil engine flush.

The only reason why I am so much checking these trims is because of the misfires and some feeling that the knocking problem (which, btw, has NOT come back yet) is somehow related and caused by them. So about misfires:
- I only noticed them when IDLE ~1000RPM but also when revving the car in PARK mostly at around ~1500RPM and also when revving the car/releasing gas/revving/releasing - at these conditions the misfires went to max of 10 in "all cylinders misfire" data and for single cylinders data I saw them at all cylinders I think (for sure they were on 3, 4, 5, 6 so definitely both banks anyway).
- While driving, I haven't seen any "all misfires" yet with checking on the graph in techstream it was always "0" for the max value while driving, no matter if I hardly accelerate or drive normally or if engine kicks in often or not.
- When idling, I can sometimes notice a little "shake" like the exhaust would be clogged or something, but it doesn't always show misfire at that moment, so probably not related.

If you say that misfires on GS450h are kinda normal when it's idling, then maybe I am looking for a problem which doesn't exist? In such case maybe I should simply drive out the whole tank with that additive, reset the adaptions and simply drive and hopefully not have any knocking or other issues at all?

I would be very grateful if you could check your MAF readings at idle (1000rpm), 2500 RPM when in Park, and the max value when hardly accelerating (with Engine RPM info too). I would compare to mine if they are somehow similar or differ a lot.
It would be also very cool if you could check and tell me how behave your SHORT/LONG fuel trims while driving and what are the max/min values you see in the graph. Maybe you can also see if your car counts random misfires when on idle and when revving in PARK and if it's also on random cylinders and how many maximum you see? If you have them too, I guess it can be indeed normal and I should not worry.

Lwerewolf

I wouldn't worry about STFT spikes. Your LTFTs sound good to me, at least - about inline with mine.

The fuel additive will reach all injectors - it mixes with the fuel, after all. Whether and how it will clean them is another story...

You can check O2s more easily with the "fuel injection amount" tests.

Your "misfires" sound just like mine, and just like... well... if you dig deep, it seems like just about every other 450h has that, 3rd or 4th gen. Huge topic on the russian club lexus forums, plenty of "evidence" on youtube videos, comments, other posts, etc, etc... all from cars that consume normal amounts of fuel, have no driveability issues whatsoever, don't consume oil and/or coolant... I honestly wouldn't worry too much about it. Mine decides seemingly randomly when to do it or not to do it. Keep in mind that the engine is always connected to the driveshaft and resp. to the differential via the planetary - the diff does have backlash, which can amplify the engine's shaking... Try filming the diff, at the flange where it connects to the driveshaft, while the car is "idling"

hybrid450

If I understand correctly, your SHORTs also sometimes spike up to even -12% while driving? And you also have the LONGs sometimes reach +7% and usually around 2% difference between banks or yours never exceed let's say -/+3%?

Hopefully the injector cleaner will do something good then, maybe I will get another one next month for some better effect. Do you recommend changing the engine oil again (I already changed it twice this year) after driving with these additives?

Regarding misfires - could you confirm that you also get the misfires counter increasing (on random cylinders) when revving the car in PARK? I want to make sure if the mentions of your digging on various forums relate only to complete idle state with ~1000RPM or it can also happen when revving on idle. To be honest this is when it happens the most of the times for me - misfiring when revving in idle or holding the revs on idle or pushing/releasing gas on idle. I made sure there are no misfires while driving and that's right - nothing there for whole road. On idle - simply rev or sometimes even put the foot on gas to start the engine and boom, some misfires (today I had 4 max). I'll try finding some posts too for a better outlook of the "issue".

I'll try recording that area on idle, sure.

Lwerewolf

The common thing is that they tend to happen when the engine has next to no load whatsoever - conveniently this also means that the drivetrain is "unloaded". Put it in "S" with the engine running, engage the parking brake and see if it does anything of the sort

I would stop obsessing about it. Alternatively, take out the whole fueling system, flow test, clean and flow test again all injectors, assemble it all again (new gaskets for pretty much the whole high pressure and low pressure fuel system, special service tools for direct injector seats, so on), see if anything changes...

https://www.clublexus.com/forums/hyb...ty-work-3.html

etc, etc - just stop

hybrid450

Short update, knocking has returned, sometimes it sounds weirder but mostly it knocks the same as before. Now when I was so much focused on fuel trims, I instantly noticed a drastic change of long fuel trims when the knocking appeared - LONGs are now around +14% on B1 and +16% on B2 while driving harder, and around +10% while driving normally, and around -3% / -1% when idling. I will be inspecting spark plugs with my friend this week, also replacing all of them with new ones from Denso (even though they are kinda new, 40k mileage), and I will replace the driver side coils with new ones this time, also Denso.

High numbers on both banks would suggest a vacuum leak, but it would be the highest on idle, and it's higher when driving the car, so either something with plugs or injectors (fuel pressure in Techstream is always reported to be around the target pressure, so I would rule out the pump issues), but why both banks act so high on trims? Would e.g. 1 spark plug cause the whole system to go crazy? And I still don't understand why it works perfectly fine for around 4 weeks with not a single knock, then out of nothing it starts knocking and keeps knocking every day...

I'll be posting update in the middle of the week hopefully.

Lwerewolf

Both banks the way you said it = fueling. IMO the knocking being linked to higher trims is a good argument for that as well. The way you describe it, I HIGHLY doubt that it has anything to do with the ignition system, plus those parts ain't cheap.

IMO buy gaskets for the fuel components from the tank up to (and including) the high pressure pump, remove it all and check (both pumps, camshaft lobe, NEW filter, etc)... and if there are metallic shavings after the HPFP... bad. Those injectors cost a good amount.

hybrid450

I'm giving the car to a different workshop this week for a diagnosis, maybe they will have some new ideas considering all the replaced stuff. A set of new spark plugs and 3 new NGK coils didn't help at all. The filter for fuel pump is new, I already replaced it. I doubt it's the HP fuel pump, it sounds normal, pressure seems okay, and the car doesn't lose power. I also doubt that two injectors, at least one per each bank would be stuck once in a time, both at same time.

I'm starting to think it's something inside the engine itself, e.g. VVTI gears or maybe the chain off by one tooth or something? I conducted an active test in Techstream for VVTI system and the results seem to be correct (the engine runs very roughly on positive values, goes back to normal idle on negative setting on the slider), but what I noticed is that changing the slider for Bank 1 changes the fuel trims for Bank 2 to positive ~15%, and vice versa for playing with Bank 2 setting. I'm not saying it's the issue, but I mean that these can have a very big influence on the fuel trims and maybe somehow cause the knocking. And now when I think I had my timing chains replaced (VVTI gears stayed original), and the first knocking occurred like 2 months after the replacement, maybe it's a clue... or just another blind lead.

I had a new issue this week, most likely connected to the knocking, I started the car in EV mode, drove like 10 meters and CHECK HYBRID SYSTEM popped up, I noticed the engine does not start at all and the car runs on battery only. I quickly connected to the OBD scanner and there was only one code (permanent) for P3191 being "engine could not start" error. Sadly I only had the standard OBD tool so I didn't see all the freeze frame data, but the general parameters didn't show any weird stuff for me. Clearing the code luckily fixed the issue and I could get back home, but once during the ride, when I was approaching to a stop, the engine was running very roughly (I can compare it to a similar rough idle when running that VVTI active test) accompanied with the knocking, went back to normal after I took off from the stop (still knocking). I am sad there were no more errors, only that generic one, so still no any clue... but I assume it's getting worse, so I hope I will at least be able to get safely to the mechanics because it's a long way.

Lwerewolf

This is shaping up to be the weirdest case of a vvt-i actuator/variator failure.

The most recent one that I'm aware of (locally) was "typical" up until the point of failure:

-rattle on startup, 1 to 2 seconds (while the oil pressure is building up)
-at the end, car couldn't restart the engine, same error (from the hybrid ECU), no engine errors
-loosened vvt-i variator bolts

Anyways, haven't heard of a noise such as the one you're experiencing being made continuously while driving.

This is the thread (you'll need to use google translate).

Needless to say, I wouldn't drive it. Tear it down, check the variators. I'd replace all of them at once, WITH the chain and all assorted pulleys/tensioners - old sprockets wear chains fast, old chains wear sprockets fast... so on, so on.

You might want to check the vvt-i solenoids as well, or rather, that should be the first thing to do

Good luck!

Xenith

Wow would not of picked it as a vvti fault at all good luck

Lwerewolf

OP hasn't replied, we don't know for sure. Just saying that it's a possibility, given what I've read about recently.

hybrid450

Hey again, I finally found some time to give you an update in case someone has a similar issue in the future, knocking problem is totally gone since March. Short version - the culprit was the fuel pump in the tank. Replaced with a used one, works as charm. BTW, this also fixed the issue I had in the other thread related to rev cutting at some higher speeds.

And a long version:
I drove to a mechanic 5 hours away from me, with a full list of replaced things and detailed description etc. After a few hours, they suspected the high pressure fuel pump and offered replacing it with a used one if I stayed for a few more days. I was already appointed at a Lexus dealer to check it too, so I took the car from them to the dealer. Again with a list and description (including my fuel trims getting high when knocking occurs), after a few hours they called and also suspected either the high pressure fuel pump OR the fuel pump in the trunk. They checked the pressure manually and the fuel pump in the trunk was pushing fuel with too low pressure (like 2-3 bars lower than it should). They offered me to replace both pumps for used ones to confirm the issue, also offering a replacement car for that time, but I couldn't stay there for the weekend, so I kindly asked to prepare the car and I wanted to replace both pumps at my local mechanic.

They said it would be ready like at 5PM (they were closing at 6PM), they also wanted to show me my fuel pump, so I went to the service area and they showed me how much dirt came from the pump when they pressured some air into it, I was shocked - the outcomings were almost black and there were even some dirt pieces in the spilled gas. They also informed me that all that mess was from the fuel filter, which they also indicated much heavier than it should be due to all that dirt, and because to it, the pump itself was getting broken over time and sucking in dirt/air instead of fuel. This in turn leaded to not enough fuel transferred to the high fuel pressure pump, which provided not enough fuel to the cylinders which in turn could cause misfires (even not detectable in Techstream) and as you know, in hybrids misfires can cause knocking noises.

It took them some time to put it back, it was already their closing hour, but they finally gave me the car saying they couldn't start the engine after they first put the pump in, but taking out / cleaning again helped and it turned on. I was happy, because the car was ALREADY not knocking after this cleaning. I asked if I can drive home safely, they could not confirm that because my pump was a real mess. So... I left the parking lot, they closed the gate and boom, all the errors in the world popped on dashboard, so I immediately stopped at nearest parking after the dealer. I scanned the code quickly and it was something like could not start/crank the engine. I quickly ran to them - gate closed, but I saw they have a backdoor gate so I quickly run around and I came in, but front doors were closed, tried to knock and wave but no one saw So I run to the service area gates and knocked there, finally someone let me in, one of the mechanics which showed me the pump... so I described the situation, and the boss came in pretty angry because they were already going home, but they gave me a replacement car - NX 300h. I was able to find a used pump for my model very cheap, purchased it directly to the dealer, right after it came, they took my car the same day and called that it's working fine, no knocking etc.

So yeah, I drove for it, got the car, paid for replacement, and drove home. On the way, I tanked the car fully - first issue I noticed, the fuel gauge didn't go all the way up, it was like 4/5. I thought maybe I took the pistol too early, drove home - boom, the fuel gauge was around 1/5 and suddenly went 3/5 by itself... Good I had reset the odometer after tanking. Tanking to full again gave the same result of ~4/5 tank full on the gauge instead of full. I called them, they sent me the fuel level meter from my original fuel pump assembly, I changed it at local Toyota dealer and finally everything is fine.

NO freaking knocking ever since, car runs great, fuel level shows up correctly on dashboard. I also replaced the other coils (so all of them are new and the same brand) and I checked my readings from time to time - the misfires still happen just like before (in Techstream, random cylinders, when idle or revving on idle, but I ignored that already), and the Long Term Fuel Trims never exceed +10% anymore, the highest I read was 5/7% positive when driving faster; and when releasing the gas pedal or on low revs, the lowest I saw was -5% negative (once it was -10%, but it happened only once and could not replicate it), I am not sure what the hell is still wrong there, but I decided to ignore that as well - car drives fine, power is there, no fuel consumption issues for me. Maybe that HP fuel pump got some issues because of too low pressure before, but I decided to run with it until something brakes again, I already wasted too much on fixing this issue while I could only replace the fuel pump... The thing I regret the most is not replacing the transmission back to mine, because I had the opportunity to do the replacement for free and get back the money for that transmission I bought - mine is on sale and no one even asked about it for the whole time.

That's it, end of story, hopefully that was the last thing I had to do this year from mechanical area.

petershen

Thanks a lot for sharing this! I have this random idle stutter... I've gone through a lot of the diagnostics that you all have done, I will go replace my in-tank low pressure pump and report back

Did you replace the entire fuel pump assembly including the float?

hybrid450

Glad to hear I am not the only one with such weird thing. If you have the same sound and only when engine runs then sure, go ahead, especially if you already tried other things. In my case the fuel pump was the cheapest to replace and buy, but sadly the last after so many parts replaced. I purchased a used fuel pump - it MUST be from GS450h, I had one from GS300 and it even looked different. It was whole assembly with the float, but I had an issue with that "new" float, because my fuel gauge was not showing full tank (it was ~3/4 on gauge) and when reaching almost empty, it magically went to half full. Just saying, maybe yours will work correctly, but I suggest you keep the old float just in case - it can be replaced separately, or test the new float before assembling everything.

Also check your Long Term fuel trims, mine went much higher than normally when the car was knocking.

Hope it helps, let us know!

Lwerewolf

You're not the only one. I still haven't gotten around to making a smoke machine for induction leak testing >_<

The fuel pump costs a ridiculous amount when new - more than $400 in my case. I've ordered both filters and all the gaskets and other small parts around the system over a month ago, still waiting for the post-pump fuel filter to arrive. Anyways, good preventative maintenance.

hybrid450

You're just doing it for maintenance or began to have some issues too?

When they replaced my pump at the dealer, they checked how much is a new one (the whole assembly with float, filter, pump etc) and even they were shocked because it was around 1000$, so even with a good discount it would be somewhere around 800$ I guess, but I didn't check at Amayama - usually it was cheaper there even with tax costs.