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Engine Hesitation (All makes/models)
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My Camry's data shows thermistor has negative temperature coefficient (low temp high value resistance
Resistance:
-20 °C (-4 °F) 13.6 - 18.4 KOhm
20 °C (68 °F) 2.21 - 2.69 KOhm
60 °C (140 °F) 0.493 - 0.667 KOhm ) while the Lexus indicated positive temperature coefficient.
Would Lexus' MAF be interchangeable with Camry's MAF ?? I don't think so
One measurement tells you that the Lexus IAT has a positive temperature coefficient....???
THe MAF/IAT spent the afternoon in the refrigerantor at 41.5F, measured ~4,049 ohms.
Increasing resistance with lowering temperature.
Looks like I will be using a 2K ohm series resistor to simulate COLD intake airflow which should result in a RICH A/F mixture.
Is this what happened to your Lexus?
Thanks, nice to be of help.
Unscientific testing........
With switch in "lean" position, 7 miles "out" at 55MPH average MPG was 30, on return it was 24 MPG. With switch in "rich" position, "out" MPG was 24 and return was 21.9. Average MPG was reset just as vehicle was locked into cruise at 55 MPH.
Haven't done enough driving to tell if the "bumped from behind" or "slingshot effect" is still present due to upshifting during closed throttle coastdown.
I am a regular browser of this and other Toyota forums. I never wanted to get involved with discussions, just here to see what others say.
Here's a 2 cents worth opinion about the hesitation complaint a few of you are beating to death. It's getting tiresome to see the same 5 or 6 usernames in all the Toyota topics every day, all day. It's been like that for at least a year.
What's with you guys? I don't doubt your reasons for dissatisfaction. BUT, is it really necessary to keep repeating the same stuff about your hesitation issues day in and day out in ALL the Toyota forums? How many times does it take to get your message across? Why is it necessary to do this in every Toyota forum in this site? What are you expecting to accomplish by this?
I'm getting fed up with constant reminders about accidents waiting to happen or transaxles are falling off or they are brainwashed or they must be on Toyota staff or aliens from another evil empire, blah, blah. You even complain about posters who come on board to say they don't have any complaints.
Well, like some others are telling you, there are thousands if not hundreds of thousands of owners just like me who are OK with their choices. You don't speak for them, and all these reminders by 5 or 6 of you don't reflect their experiences.
I'm not saying there aren't problems with Toyota. All manufacturers have issues.
There are lots of other issues to learn about in these forums. Just give us a break from yours to make room for them.
Profile for hylyner
User: hylyner
Email: private
Member since: October 12, 2005
Last login on: October 12, 2005
Agree 100% that there are "lots of other issues to learn about", however this forum was started to specifically discuss the hesitation issue. Even though it is for the problem "in all makes", it grew out of the Highlander Problems discussion forum. So, to reiterate mert2's comments, if this isn't of interest to you, then don't visit here. I am pretty sure that those experiencing the problem find it helpful and, if they need a break, they take one, rather than gripe about others discussing the problem.
I am also somewhat disappointed. When I began looking at various cars, I came to the Edmunds site because I considered them to be a trusted source of unbiased information. When I first saw some of the posts about hesitation and the claims of safety issues I was concerned. Based on a quick browse of these boards I even considered deciding against the Highlander because of some of the claims, and I would have missed out on a truly wonderful car.
After looking closer however I realized that it was indeed the same few people posting over and over and over, making what I consider to be many baseless claims and assumptions. I am not talking about the statements that there may be a problem with your particular car, but the obvious exaggerations. I have to wonder just how outlandish a claim a person can make on an Edmunds board? I have seen absurd posts comparing cars to coffins and people getting run over (none of which happened) that I really believe are a discredit to the issue, as well and the entire Edmunds site.
Based on my personal experience here, I would no longer advise anyone to come to these boards for fair, unbiased information. I realize that Edmunds is not the source of the information, but I think that allowing such obviously untrue statements about deathtraps, brainwashing and public admissions that have never occurred, is not fair to the motoring public.
My 2 cents.
I presume that only people interested in this problem would attend this forum in other words. We think everybody should have a home at Edmunds if possible.
it is a safety problem. the anecdotes of people who have been in traffic and had their vehicle not respond to their command for increased engine output should be evidence enough for any person.
there is nothing exaggerating or outlandish about an engine hesitation and an impact to safety.
"I have seen absurd posts comparing cars to coffins and people getting run over (none of which happened) that I really believe are a discredit to the issue, as well as the entire edmunds site."
Jim, may I ever so kindly ask you to "prove it", validate it with factual data, with regard to your statement "(none of which happened)"...??
Look, I haven't personally encountered any of the current throttle delay, hesitation, symptoms. And I know I have related this previously but I think it bears repeating.
Back in 91-92 after I had just purchased my new 1992 LS400 I experienced some instances with its Trac system that were somewhat frightening. As I pulled from my residential street onto the main thoroughfare, often lots of fast moving traffic, if it had rained my rear tires would often slip briefly on the crosswalk plastic stripping. That brief wheelslip would result in Trac activation, braking the slipping wheel and instantly dethrottling the engine.
As a result on several occassions I found myself stalled in front of some very fast moving traffic. I cannot tell you how long it would take the Trac system to "unwind" the dethrottling servo stepper motor, maybe it was a second or more. But to me sitting there waiting for the engine to respond or to be hit by an oncoming vehicle it did seem like a very long time.
It didn't take very many of these frightening instances for me to learn to turn the Trac system off each and every time I started the car.
By the time I purchased my MY2000 GS300 the Trac system had evolved, been revised. The brakes would still be applied instantly upon wheelslip, but the dethrottling was delayed a few hundred milliseconds to allow teh driver to react and lift the gas pedal to a point of regaining traction.
Be that as it may, I think I can speak for all of us in that we are thankful, pleased even, that your Highlander doesn't exhibit the symptom. Clearly, the number of V6/5-speed DBW transaxle vehicles that work properly in this regard are in the majority. That should mean that Toyota will soon know why the few have the flaw and then a fix will be on the way.
That's what it's for.
My message was for those few who post here all the time, but constantly repeat their gripes at ALL the other Toyota forums. All I wanted to say was PLEASE LEAVE SOME ROOM AT THE OTHER FORUMS FOR THE REST OF US. Thanks.
wwest is probably the most prolific poster, but if you look at all the Toyota forums, you'll find there and in other forums for other makes and models, he doesn't discuss hesitation but other things of benefits to owners with other problems.
scoti has been posting in other Toyota forums, perhaps others too, trying to encourage people posting in those other forums to bring their hesitation related discussions here.
as for me - if i qualify as one of your "few", i've posted a few times recently in the Hylander P+S forum, but only to counter another series of posts. my mistake for not keeping it here.
you have plenty of bandwidth to contribute to the discussions. you' ve only been a member since today, so you've got plenty of writing to do to catch up with us!!!
in all fairness, if you look at the posts of wwest, scoti, myself, and a few others, what you'll find is a discussion trying to come to grips with why some people don't have the problem, while others do, and why the first population of people constantly attempt to negate the observations of those experiencing the issue. that's not very genuine and doesn't get anyone anywhere. we are also debating what might be at root cause, and how we might capture the event so everyone can learn by it.
personally i'm sorry i posted in the Hylander P+S forum...but, this is the forum that started the discussion as i recall.
i am not sorry i asserted a long time ago that this is a safety issue. this is neither outlandish or an exaggeration.
time will tell. maybe someday you'll thank wwest for his endless pursuit of the underlying root cause, and willingness to postuate experiments to further our understanding of the phenomenon.
i promise i don't bite. so here's your opportunity to elaborate on your position.
go for it.
I don't think there is a limit to how many times a person can repeat them selfs, if so the host needs to make this know.
I think the problem that the shut up already crowd has is that they know any bad publicity about any defects with any vehicle effects it's resale.
You should also know that when you trade in your vechile the dealer will pull up the stats on it to see what kinds of problems have been reported on it.
The dealer will use this information in deciding how much to offer you for your trade in.........Toyota also monitors this discussion board to develop a consensus in order to advise dealers what to tell customers about specfic problems.
Because there continue to be posts by new people experiencing the problem on these other forums, it is obvious that people aren't readily being led to this discussion. Maybe the name "engine" hesitation throws them off.
w/e, it shouldn't be a big deal to direct folks here if there is something of interest being reported here. One post on the subject does not dominate the discussion. Not allowing one post makes it appear that Edmunds is trying to hide the discussion.
Please allow me to explain. All I wanted to happen was for the 5 or 6 of you who mainly hang out here to leave a little room for others at all the other Toyota forums.
Every time I scrolled through them, you guys were there. It was mostly about this hesitation, little else. Some posts were informative, some were plainly vindictive, some just seemed like trolling for others to jump in.
After a few months passed I realized the same things were being repeated again and again over and over. Mostly the same things being rehashed.
Then a few others started to mention their concerns. It finally came to a head in the Highlander forum when all there was for a whole week was you guys going on and on. That's when I felt enough was enough and made my decision to be heard.
I think Edmunds made room for you by opening up this forum way back when. There's no reason why you can't carry on your debate here, no on has restricted you and you haven't been asked to.
You yourself, and the others in your group regularly scan all the other Toyota forums. I say that because your usernames are very prominent there. No reason why you can't continue to do it, inform about this topic, or pass on news about improvements. Just ease up a little. Others would like to be heard. Your problems aren't the only ones.
I just cannot see where you are restricted as you or your friends say. There's no reason to get all in a huff when somene asks for a little understanding and common courtesy. Lighten up. It's not the end of the world.
If I were shopping for a Toyota and did't heard this mentioned in the regular discussions, bought the car, had the problem and asked why it wasn't discussed in the other discussions, I sure wouldn't accept the answer that "some people didn't want to hear about problems so it was only discussed in the 'Hesitation' discussion."
2014 Malibu 2LT, 2015 Cruze 2LT,
Sheesh! NOT everyone experiences it, and there have been reports of folks that have had some significant improvement from the TSB.
respectfully, Jeff
(who enjoys his Highlander(s) and has no hesitation, and has been quiet for some time, but just couldn't let that comment go by un answered.)
Toyota has told many owners it is a common characteristic (just read through the posts). Bkinblk was told in his artibration hearing that it was an intentional component of the design to protect the drive train. It's existence is acknowledged by Toyota and Lexus in their Technical Service Bulletins. When Toyota announced the TSB in the Pittsburgh Post article, their spokesperson admitted that the TSB would not improve the condition 100 percent of the time, so it certainly is not being fixed across the board.
What I have contended, to explain why some like you don't seem to be experiencing it, is that the hesitation can be so slight that it is frequently not discernible (i.e., just a fraction of second). It is also unpredictable when it occurs. A slight hesitation occuring inconsistently could very well go unnoticed. But when it gets into the 1 - 2 second range and occurs repeatedly but unpredictably, you have a problem.
Sorry, and thanks for setting me straight. I have stated before that i sympathise with those who do experience it, but am grateful that I don't. And I don't blame anyone for continuing to post their experiences, theories, attempts at fixes, etc. I for one would be here posting nearly everyday looking for help if I had an issue with any of my cars that i felt was wrong.
Jeff
The OTHER forums are for other subjects. I never said it was out of order to "invite" or "announce" the engine hesitation problem in other Toyota topics, such as, e.g., "hey, I noticed you mentioned engine hesitation. Please come over to (link here) and talk to us. We're working on it"
That's FINE. What probably ISN'T a good idea is to actually start talking about the engine hesitation issue in another Toyota forum where people are joining or participating in a far more generalized "message flow" if you will.
Hope that clears it up. I hearby declare this bridge officially open (snip, snip) :P
in general noone is looking for "new blood". that is rather base.
we don't need more reports by more people driving toyotas that they have a hesitation problem to believe it is a real issue or to keep the thread alive.
now, if they are driving another make, THAT would be new information that could spark additional discussion.
funny how that isn't happening, huh?
Thanks
I would look at the choke setting first to be sure it's going completely on (thermostatic spring getting weak after 20 years of heat?) and then that it's not pulling off too little or two much.
And I would post in this discussion
jim735, "Got a Quick, Technical Question?" #2096, 16 Oct 2005 11:40 pm
where several knowledgeable people read and Alcan is one who is a mechanic. He probably has knowledge that can help you!
2014 Malibu 2LT, 2015 Cruze 2LT,
Was that the carburetor where they had two-stage pulloff on the choke? Or was it electric heater after starting the car.
How can I find out?
Thanks
Today I plan on extending the switching capability with a multi-wire cable so I can change the IAT from normal, lean, and rich from inside the car on the fly while monitoring the instant MPG for results.
Insofar as I can tell my RX still upshifts in the very same instances as before regardless of switch setting.
my creating this MAF mod, you're playing with dynamic leaning. the danger here, if you go too lean, i suspect you can do some damage due to heating.
And that's exactly why I'm trying the next step, to be able to change the simulated intake temperature signal from rich to lean on the fly, in real time, to keep the ECU confused.
I suspect that the oxygen sensor has the final "say" on the mixture ratio so over time a false IAT signal would be summed out of the A/F mixture computational equation.
why are you trying to confuse the ECU again? i just haven't been following what you are doing (ie the "why")...
If, on the other hand, the signal falsification changes from lean to rich every so often the ECU has no chance to "adjust" to either.
So, why are we here, what is this about.
First, there have been reports of dealers recommeding that the use of premium fuels would help to alleviate the instances of engine/throttle hesitation/delay. And I think, based on my readings, that some owners have reported that the use of premium fuels does help.
Second, we have this report from jbuchanan that he changed out the MAF/IAT module for a customer and it totally eliminated the symptom.
So, premium fuels would undoubtedly make the engine less likely to knock/ping at specific settings and environmental circumstances wherein low octane fuels might.
And I can readily see that a new, different, MAF/IAT module might, just by happenstance, result in a richer A/F mixture and thereby make the engine less likely to knock/ping.
So the goal is to provide a false, biased, MAF/IAT signal so the A/F mixture will always be on the rich side. As a "control", it doesn't hurt to be able to crosscheck using a false/biased signal to lean out the mixture.
With regards to the leaning mode resulting in heating....
I trust that the ECU will always protect the engine by eliminating any knock/ping should it begin to occur. And yes, the catalytic converter might be damaged if this were done over a long term, but I doubt any damage will occur for the short term experiment required to determine if this affects the hesitation symptom.
And keep in mind that the goal of the experiment is to run the engine with an artificially "rich" A/F mixture, and in that case the engine would definitely be less likely to knock/ping and would undoubtedly run cooler due to the cooling effect of the rich mixture.
After about 350 miles, about half hwy, I can't detect any difference in engine response or fuel economy regardless of MAF/IAT switch position. I suspect it might be a lot like trying to discern the difference between using premium fuel vs not.
The good new is that there have been no detectable adverse effects.
So, bkinblk, if you will tell me where to send your "new" MAF/IAT sensor module....
email: ceo@(companyname).com
But I would say be cautious about pursuing this under the lemon law.
Toyota must be very well aware that whatever the causative factors are, it appears that it is possible for any vehicle, by random chance, to be subject to engine hesitation. That means its really class action time and therefore Toyota cannot let this get out of hand by repurchasing too many cars under the lemon law.
If you should succeed don't be too surprised if the repurchase paperwork states an entirely different cause other than engine hesitation.
A case in point.
Over on the Lincoln Aviator thread there is news that Ford just repurchased a customers car but under another "symptom" altogether rather than the customers core HVAC complaint. I susppect they did that because the HVAC problem was common to the entire fleet.
Like what I posted 7-8 months ago, you have nothing to lose because the attorney charges you nothing if you lose, and Toyota will pay the attorney fees if you win.
Good luck and keep us posted.