Zeke21

Got the car back and it appears to be driving fine again but I'll report back should the symptom come back, need to drive it longer to really determine. Lexus performed the ECM re-calibration. I was told that depending on the type of oil used, it can get into the valve guides and cause the engine to make some additional noise which sets off the denotation sensor. The ecu thinks the car is detonating and changes timing etc...causing the hesitation. The re-calibration basically tells the ECM to look for a noise frequency other than the one caused by the issue with the guides. I was told by my dealership it was rather rare to have to replace the valves etc and that if your spark plugs appear to be in ok or normal wear and tear shape there is no need to replace the heads and valves. The revised parts apparently do a better job of keeping this condition of happening and further the newer models (13+) not affected by this also come with the latest calibration already installed.

I also had them install new spark plugs while it was there given my mileage. In the past I probably would have just done them myself but with a nearly one year old and work its a little hard to find some spare time right now.

What's funny I was asked who last changed my oil by the service dept. I told them, since I have owned the car I have had the oil change at the same place (a small independent shop whom I trust) with the same kind of oil brand and weight etc. The one time I had it changed by someone else was this dealership, when they also updated my map. This was back in December 2016. My hesitation issues started just after the first of the year. The only response...ok, so it's our oil.

ausLX

Okay, so I am bumping a 2 year old thread. I realise that there is another thread with more recent responses, but this is the longest thread I could find after scouring the forum, so I chose to go with this one since neither thread ever offered a true solution to the problem.
I have a 2008 LS460, and have recently been experiencing the throttle hesitation problem. I have had an oil change done since buying the car, but I don't think this is the culprit because I didn't notice any lag issues immediately after the oil change, the first problem happened
about 1000 miles after the oil change.
Anyway, 2 days ago I drove my LS to the beach, something like a 62 mile trip one way. I didn't notice anything on the way there, but on the way home I was cruising along in traffic and I noticed that my car was really slow to respond when I would apply the accelerator. I would
be travelling at about 60 miles an hour, both in cruise and with cruise control disengaged, and I noticed that I had to literally stomp the pedal all the way to the floor to even get a response, and I would watch the revs climb to 3500 - 4000RPM at which point the car would start to
accelerate slowly, whilst the engine was screaming yet I was going nowhere fast. It was in PWR mode the whole time.

The next day, I had the same issue, except it was from a standing start. I stopped at traffic lights, and I had a Toyota Corolla hatch pull up on my left next to me (yes I'm in Australia) with the intention of trying to get in front of me through the intersection since his lane merged into mine.
So naturally, I weighed up the pros and cons of flooring it when the light turned green, and I quickly decided that my 4.6 Litre v8 RWD sedan stood a better than average chance of beating his 1.8 - 2Litre 4 cylinder FWD hatchback. I was stopped for about 2 - 3 seconds, and then
the light turned green.

I stomped on the gas. The engine started revving the **** out of itself all the way up to 4000rpm.

But, nothing. I wasn't going anywhere. My LS did start moving, but it was like it was crawling. The Corolla got in front of me in less than 5 metres, so I decided to take my foot off the gas since I wasn't going anywhere and he was going to run into me if I tried to keep up with him.
I'd never experienced such a bad lag episode before then. Sure, I do have a few other times when the acceleration issue occurred, but I guess this one really hit home as to how bad and dangerous it can be. I was in PWR mode this time too. I fact, I have started keeping PWR mode
on all the time because I want to try and mitigate the lag issue whenever it decides to pop up.

So the third day, today, there was no trace of lag. I started the car, switched it into S8 and drove like a granny while it warmed up (as I always do), then turned on PWR mode and switched it into Nintendo (DS) when the engine reached operating temperature.
From a standing start and from a rolling start at 37 - 60 miles an hour there was maybe a half second of lag at the most, followed by myself getting thrown back into my seat, my coffee almost falling out of the cupholder, and the cars behind me quickly getting smaller and smaller.
I'm not going to get the heads replaced. I think I read a post from 2015 that said it cost them $7000. That's way too much to pay for something that has still not been shown to be a complete fix. I'm also leaving the software updates to a last resort, since they are non reversible
and also not a complete fix. So I guess I unplug the battery and go from there?

miket000

I'm curious how many miles you have on your 08?

mdpresco

WIth about 80,000 miles, I had the hesitation with my 07 LS460. It would usually settle down after 200 miles. The dealer reprogrammed the ECM about 2 years ago. The hesitation went away and hasn’t returned. Some owners had their cylinder heads replaced to cure the problem. I believe it is one of those problems known to Lexus but not widespread enough to issue a recall.

Good Luck.

ausLX

The hesitation in my 08 only pops up every so often. Not enough to make me call a dealer and ask them if they can do the software update and for how much, but sometimes it happens at the worst time like when I pull out in front of traffic. I forgot to mention that I only ever put 98 octane in my car, and mostly bought from the same source. It's been driving fine for the last 2 days, no lag at all.

DrQuality

Earlier comments from Nospinzone, abs, Kennyr44 & Doublebase led me to suspect that this official 20 upper viscosity constraint was yet another Lexus Murica!-only rule … being tied to the US CAFE laws about auto manufacturers hitting fleet-wide MPG targets.

So I just spent an hour looking at Lexus LS460 Owner's Manuals from around the world. Only in the USA & Canada are the choices officially limited to 0w20 & 5w20. In Britain, Ireland & Australia, the owner is directed to choose the viscosity (appropriate to the operating environment) from among 0w20, 5w20, 5w30, 10w30, 15w40 & even 20w50. Even in ever-frigid Finland, Sweden & Norway, owners have access to all these viscosity options … and they were in fact all available in every Manual for the European Market that I opened.

As example, I've attached a copy of the relevant pages from the Irish-version of the 2011 Lexus LS460 Owner's Manual.

Very frustrating. Because of USA CAFE regulations that eternally increase MPG expectations, auto manufacturers are being forced to employ less viscous oil in order to gain greater fuel efficiency … at the expense of less actual engine protection. See https://bit.ly/3CtfrrM . The second graph at that website shows that a 30 upper viscosity oil (with a HTHS somewhat above 3.0) is maximizing engine protection … and at almost twice the rate of protection provided by an 20 upper viscosity oil (with an HTHS of about 2.5-2.7). And check out a few SAE Viscosity Temperature Charts; more than a few suggest that the protection of 20 upper viscosity oil begins to diminish after/around 75°F ambient, while the protection of 30 upper viscosity oil begins to diminish only after/around 95°F ambient. And Internet-searching on "5w20 5w30" brings up on-point many discussions, YouTube videos, etc. on this topic.

Perhaps if we had all been using 5w30 all along, those lower tension rings (also an artifact of CAFE standards) wouldn't be wearing out causing increasing oil consumption after 150k and such.

Anfanger

If you are spending time on researching the subject, please, provide references to sources that do not have conflict of interests. Citing a lubricant manufacturer is as a trusted source is laughable at least.

Plots without units and error bars are useless, they provide no information and, as result, no proof of anything but ignorance.

Wear in valve guides is not same as wear of piston rings.

lwphat66

If one does an internet search for "LS460 Hesitation on Acceleration", the 03 MAY 2017 TSIB (L-SB-0122-17) does show up with a little searching effort.

mdpresco

I'm glad this thread revived! I'm glad Lexus has improved parts for replacement. But I have a few questions:

• This looks to be warrantied if the car has been in service for less than 10 years. So for us 2007 owners would be out of pocket?
• I had my ECM reflashed a few years ago. Now the hesitation has returned for the 100-200 miles after an oil change. And then it goes away. Any ideas why?

lwphat66

At what RPMs did you feel the hesitation occurring?

mdpresco

It happens when accelerating. The engine can go to 3500 to 4000 rpm with the car barely moving any faster. I get off the pedal and wait a moment and try to accelerate again.

DrQuality

SUMMARY OF HESITATION DISCUSSIONS & THREADS

I just spent the better part of an entire week reading & re-reading about 18 threads (some shorter & sweeter, a few quite lengthy & intense) about early-year LS460 engine hesitation issues. As a result of the many, many contributions of knowledge & experience shared within them by other ClubLexus members over the years -- thank you so very much one & all -- there is at this point a very good understanding of much of these hesitation issues.

So I thought it might be beneficial to summarize the common points of what I read into a primer and/or starting point, for others who are dealing with this issue. That is not to say my summary encompasses every owner's comment, experience or solution … but there were indeed some commonly repetitive concepts within the threads.

I will also say I found some of the discussions in the threads to be difficult reading, as they digress into some very detailed discussions of powertrain & engine mechanics. So hopefully this summary will lighten the burden of others in that regard.

First of all, it all reads as though Lexus has never really come to a complete encompassing solution to embrace all these hesitation issues & complaints. The powertrain/ECU firmware was re-calibrated/updated at least five times early-on, the parts involved in physical repair (on the rare occasions when such was done) were initially found to be inadequate (or defective) and 'updated' … and Lexus seems to have been fairly silent regarding hesitation issues of the type that specifically emerge immediately after an oil change.

One thing that has apparently made these hesitation issues especially confusing & frustrating for owners is that … there appears (to me) to be THREE different types of hesitation issues in play, each with its own symptoms, causes and solutions. So, early-on, posters were routinely talking at cross-purpose, such as

* An owner with hesitation issue #1 was being offered (inappropriate) solutions from owners who used them to resolve their hesitation issue #2.

* An owner solved hesitation issue #1, then symptoms of hesitation issue #3 would emerge … and the owner would think the 'original' problem had returned … when actually a NEW problem had emerged.

Those sorts of things. Not only confusing to the owners posting and trying to find the correct answers … but to any late-comer trying to make sense of the information in the threads.

As the discussions continued and aged over the years, it looks as though the more active posters came to well understand there were these different types of hesitation issues all going on simultaneously, each with their own cause. But for someone just arriving to these threads, trying to make sense of it all, trying to find a solution for their own hesitation issue, that might well not be clear at all. It might read more like a wide variety of various hesitation complaints, with a bunch of different suggested solutions, some of which worked some of the time, but none of which worked all of the time.

So below, I grouped together what I came to understand as the three different types of hesitation issues, the symptoms, causes and solutions. Again, it make not address every owner's comment, experience or solution, but it did seem that eventually the threads generally reached the understanding that I have described below:

(1) Delayed response (only) when demanding full/urgent acceleration. The primary symptom is that the engine, upon such demand, disengages from the transmission for 1 or 2 seconds, then re-engages the transmission, then the transmission downshifts after which the vehicle jerks into finally delivering the requested acceleration. It appears that the cause is that the vehicle sensors are falsely detecting engine noises (caused by faulty valve guides with excessive clearance) to be engine 'knocking' detonations. The ECM/PCM logic ultimately fails to resolve its attempts to retard/adjust/correct the engine timing on-the-fly via VVT (Variable Valve Timing) in order to match all the correctly & incorrectly perceived detonations. And so, not knowing what timing to deliver, it delivers instead the pause of hesitation. This phenomenon is described with further clarity & detail at https://bit.ly/3ClAjBf . It appears from owner comments that performing the ECM/PCM (ie, Electronic or Powertrain Control Module) 'flash' (ie, a firmware calibration/update) as described in 2008's Lexus Service Bulletin L-SB-033-08 was highly successful in resolving the issue. (Note that Lexus Service Bulletin L-SB-033-08 was obsoleted & superseded in 2017 by Lexus Service Bulletin L-SB-0122-17.) The ECM/PCM flash apparently alters the knock detection frequency slightly so that it omits valve guide engine noise detection. A few posters report that it took more than one ECM/PCM flash, either in-the-shop or by return-to-shop, in order for it to correctly take permanent effect. Some posters report that if the battery was disconnected too soon after the ECM/PCM flash (thereby clearing certain ECM/PCM values/parameters), the 'driver learning mode' process (that, after a battery re-connect, creates certain ECM/PCM values/parameters that are used to fine-tune engine & transmission behaviors) became corrupted and, in turn, corrupted the effectiveness of the ECM/PCM flash. In that case, it was required that either the ECM/PCM flash be repeated and/or the battery be re-disconnected to initiate a new 'driver learning mode' process.

Though it apparently was not very frequently needed, physical replacement of the cylinder heads (as also described in the Repair Procedures within the Lexus Service Bulletins) was also sometimes required, after the flash, to sufficiently delete the erroneous valve guide engine noise. Even worse, a few posters reported that the parts used to perform their cylinder head replacements were eventually found to be inadequate or defective, causing additional various failures/errors and requiring the work to be redone with an 'updated parts list.'

These Service Bulletins are NOT an official safety recall and do not enjoy any enhanced/extended powertrain warranty; out-of-warranty, the ECM/PCM flash is not that expensive at all (my Lexus dealership only charged me $74.00 for it), however the cylinder head replacement surgery would easily cost upwards of $10,000.

(2) Constant/ongoing delayed & sluggish acceleration. The primary symptoms include sluggish acceleration or 'like-in-neutral' behaviors during vehicle turns, at idle & stop lights, during braking, during stop-and-go, during a constant slower speed, upon slowly proceeding out from a full stop, during on-ramping to limited-access highways. The driver may also observe slow-but-steady increase in RPMs without delivery of directly corresponding power/torque. It appears the most common successful solution is to perform the VSR (ie, Valve Spring Replacement) as described in "Safety Recall ALE 'Valve Spring Replacement' [2010-06-10]." As an official US safety recall, there is no expiration of the VSR work at no-cost to the owner.

However, more than a few posters report that the above-mentioned ECM/PCM flash, #1 as above, had to be ALSO subsequently applied to entirely resolve the issue.

There were some comments that claimed ONLY the ECM/PCM flash had to be applied to resolve this issue … but some of those owners might not even be aware that the VSR was already applied: they might be second+ owners … and (apparently) the VSR, as a safety recall, was frequently applied automatically to vehicles arriving in service bays, perhaps without the owner being well aware of it having been done.

So, in short, first ensure the no-cost, no-expiry VSR is/was applied, then apply the ECM/PCM flash after. If still not resolved, consider #3 scenario as below.

(3) Random hesitations, typically emerging immediately after an oil change that eventually 'go away' -- until the next oil change. The primary symptom is power hesitation events that occur almost entirely at random, and of varying intensity, that initiate shortly after completing an oil change, though there may also be delayed & sluggish acceleration events as described above under (2). Most posters report that these events self-resolve after about 100-500 miles of driving, while a few report up to 1000 miles before resolution. Thanks especially to detailed explanations/discussions by posters including Devh & Roadfrog, an informal consensus has emerged that the cause is that, after the oil change, the fresh oil lifts/cleans minor varnish & sludge deposits from around the engine that then proceed to clog the VVT (Variable Valve Timing) oil strainers and interrupt proper VVT operation that is dependent upon sufficient oil pressure. Without proper VVT, the timing of the engine is 'thrown-off' and delivers hesitation. Then the problem eventually self-resolves after the detergent in the oil has had full opportunity to finish dissolving/absorbing the deposits clogging the strainers.

The random nature and intensity of these events, in part, is coming from when the strainer deposits move around somewhat at random by whatever cause, blocking then unblocking the strainers. (In one case, Caha14 reported the problem started the day after his wife drove the car; I read that to mean her differing driving style, the roads she traveled, whatever, were enough to lift and/or agitate the deposits.)

The phenomenon is apparently more pronounced when drivers migrate to synthetic oil (that tends to lift/clean such deposits) after extensive usage of conventional/mineral/dino oil (that tends to allow such deposits to accumulate). Also, the consensus seems to be that a series of synthetic oil changes will eventually lift/clean most all of the deposits out of the system and so resolve the problem on a somewhat more permanent basis.

Some posters claim this was solved by specifically using full-synthetic TGMO (ie, Toyota Genuine Motor Oil) 0w20 (as manufactured for Toyota by Exxon/Mobil). Additionally, some posters recommend use of an engine/crankcase cleaner/flusher/detergent product to be introduced immediately prior to an oil change, to aggressively lift/clean such deposits into the oil that is going to be subsequently changed out. Such products include 'Liqui Moly 2037 Pro-Line Engine Flush,' 'Rislone 100QR Engine Treatment' … and even a Toyota-branded Engine Oil System Cleaner product (apparently only ever available at Canadian dealerships and now discontinued). However my own Internet-searching revealed many, many complaints that this type of product is so aggressive that it can readily & seriously damage an engine so, personally, I will not be comfortable applying them.

Btw, dealership service advisors & technicians sometimes argued to owners that any or all these types of hesitations were being caused by 'bad' or low-octane gasoline. However, even though theoretically such fuel could indeed cause these kinds of issues, most -- but not all -- posters stated that this argument, in their own cases, ultimately revealed to be incorrect. I believe I only saw 2 or 3 posters say that their hesitation problems ended entirely after merely switching-out their source of gasoline.

Hopefully the above summary will provide other owners with the information they require … or, if they need to read the threads for additional detail, the discussions there will now be easier to comprehend.

Happy motoring!