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What determines Knock Correction Learn Value (KCLV)?
I took my car (2016 IS200t 21k miles) to the dealer the other day and they said that my issues with hard shifts could be due to my low KCLV value, which was 17.8. The tech said that this value was worse than from using low octane fuel. I only pump 91 octane gas from Costco, but he said that he has seen several issues with Costco gas and recommended I use Chevron instead.
I plan to switch gas just to see if it actually makes a difference, but I wanted to ask if other factors determine the KCLV. I do tend to go easy on the throttle so I wonder if that is why it’s so low? The tech said that carbon build up shouldn’t be an issue since the engine uses direct and port injection.
The engine has one Knock sensor on the block below the intake runner for cylinder #3.
I think changing fuel is definitely a good first step considering it was Costco gas.
The tech said that this value was worse than from using low octane fuel. I only pump 91 octane gas from Costco, but he said that he has seen several issues with Costco gas and recommended I use Chevron instead.
Hmm, I wonder if it is something specific to the 8AR engine. I've used Costco gas a number of times with my 2GR and haven't seen any issues. Then again I also haven't measured KCLV yet...
The engine has one Knock sensor on the block below the intake runner for cylinder #3.
I think changing fuel is definitely a good first step considering it was Costco gas.
Will do. So you don’t think how I actually drive would affect the value?
I took my car (2016 IS200t 21k miles) to the dealer the other day and they said that my issues with hard shifts could be due to my low KCLV value, which was 17.8. The tech said that this value was worse than from using low octane fuel. I only pump 91 octane gas from Costco, but he said that he has seen several issues with Costco gas and recommended I use Chevron instead.
I plan to switch gas just to see if it actually makes a difference, but I wanted to ask if other factors determine the KCLV. I do tend to go easy on the throttle so I wonder if that is why it’s so low? The tech said that carbon build up shouldn’t be an issue since the engine uses direct and port injection.
I dont know why quality of gas has something to do with hard shifting.
If KCLV is low (dont really know what this is) but it looks like a knock sensor value.
It would be adjusted via ignition retard/advance timing or some sort of SFI adjustment.
Not thru shifting of the trans.
If switching gas didnt do anything on your issue, try going back at the tech and ask if they could reset memory on the ECU.
Maybe on both trans and engine ecu.
You should still be under warranty.
Knock. Feedback knock learn and global adjustments should not have anything to do with shifting. Knock is detected and as adjustment is made to fuel and timing is reduced, if it persist the global as adjustment is made to that specific range until no knock is dented for a period of time. Knock will happen in all engines, the duration and amount of knock is what triggers the global adjustment.
Personally I feel your service advisor is full of it, bad gas happens but usually its isolated to one tank every now and then, not continually, costco is rated as tier 1. If you must try different gas and monitor, but I suspect the hard shift is due to transmission programming.
I dont know why quality of gas has something to do with hard shifting.
If KCLV is low (dont really know what this is) but it looks like a knock sensor value.
It would be adjusted via ignition retard/advance timing or some sort of SFI adjustment.
Not thru shifting of the trans.
If switching gas didnt do anything on your issue, try going back at the tech and ask if they could reset memory on the ECU.
Maybe on both trans and engine ecu.
You should still be under warranty.
It is still under warranty. We disconnected the battery - is this sufficient for resetting the ECUs?
Originally Posted by TonyN
Knock. Feedback knock learn and global adjustments should not have anything to do with shifting. Knock is detected and as adjustment is made to fuel and timing is reduced, if it persist the global as adjustment is made to that specific range until no knock is dented for a period of time. Knock will happen in all engines, the duration and amount of knock is what triggers the global adjustment.
Personally I feel your service advisor is full of it, bad gas happens but usually its isolated to one tank every now and then, not continually, costco is rated as tier 1. If you must try different gas and monitor, but I suspect the hard shift is due to transmission programming.
I also have hard shift on fast deceleration
Yeah I will try different gas just to prove it to the tech.
Does engine knock detection only look for knock at certain frequencies? Could my hard shifts be falsely detected as knock?
Costco is top tier gas, same as Chevron. Only used Chevron (and shell) my entire life. Until I looked into it and the only "proof" I found that Chevron is better was provided by Chevron themselves.
The KCLV is raised by driving habits. I'm no Lexus tech but I'd think he's full of it too. Never read that having anything to do with transmission behavior. Would like to know what results you see after a couple tanks of Chevron. But I'd guess none.
I switched to Costco gas now and I'll go check my KCLV. May be insightful...
I think from the comments so far it's a little tough to draw the line from bad gas to hard shifting.
Let's assume there is something wrong with the fuel in this instance and the ECU is detecting a knock that it's trying to compensate for by adjusting the timing.
When the tranny is shifting, the ECU actually adjusts the timing to smooth out the shifts...this is done normally as just part of how the vehicle shifts.
If the ECU is already tackling an engine knock by adjusting timing, then it would stand to reason that those tranny shifts are not going to be as smooth as they could be.
Hence the comment by the tech to change fuel stations. He may not have been inclined to go into detailed explanation as to why, but that's the relationship between the fuel and the shifting.
It wouldn't be a bad idea to change stations for a few full tanks and then have the ECU reset.
Realistically the ECU will bring the timing and shifting back under control over time as the knocking issue disappears with the new fuel.
So you can wait or reset...either way there is a learning curve...just depends which is faster.
I'm not sure how consistent Costco gas is across the board, but around me I wouldn't touch it with a 10 foot pole...Top Tier or Tier one, or whatever the hell they call it.
I'll stick with my Shell Premium all day long thanks.
I think from the comments so far it's a little tough to draw the line from bad gas to hard shifting.
Let's assume there is something wrong with the fuel in this instance and the ECU is detecting a knock that it's trying to compensate for by adjusting the timing.
When the tranny is shifting, the ECU actually adjusts the timing to smooth out the shifts...this is done normally as just part of how the vehicle shifts.
If the ECU is already tackling an engine knock by adjusting timing, then it would stand to reason that those tranny shifts are not going to be as smooth as they could be.
Hence the comment by the tech to change fuel stations. He may not have been inclined to go into detailed explanation as to why, but that's the relationship between the fuel and the shifting.
It wouldn't be a bad idea to change stations for a few full tanks and then have the ECU reset.
Realistically the ECU will bring the timing and shifting back under control over time as the knocking issue disappears with the new fuel.
So you can wait or reset...either way there is a learning curve...just depends which is faster.
I'm not sure how consistent Costco gas is across the board, but around me I wouldn't touch it with a 10 foot pole...Top Tier or Tier one, or whatever the hell they call it.
I'll stick with my Shell Premium all day long thanks.
That makes sense to me. My only concern is that I am now changing two variables (my driving habit and gas). If driving habit does affect KCLV, then I think I should consider driving the same and just changing fuel to see if fuel is the reason for the low value.
That makes sense to me. My only concern is that I am now changing two variables (my driving habit and gas). If driving habit does affect KCLV, then I think I should consider driving the same and just changing fuel to see if fuel is the reason for the low value.
I would agree and just change the fuel for now. But be patient to give it at least 2 full tanks, if not 3.
That way you assure all the Costco gas is gone.
I'm not sure how consistent Costco gas is across the board, but around me I wouldn't touch it with a 10 foot pole...Top Tier or Tier one, or whatever the hell they call it.
I'll stick with my Shell Premium all day long thanks.
No clue on the "consistency", but it's Top Tier, so there's that.
To elaborate on my consistency comment...it was meant to reference the fact that the truck that fills the Costco station near you, won't be the same truck that fills the station near me.
And where both those trucks pick up the fuel to deliver to the station will also be a different place.
My point being that it's up to the refinery to produce the fuel we ultimately put in our tanks, and while you'd like to think that the refineries would be held to a standard across the board if they are supplying Costco with fuel, at the end of the day each one is a business onto itself.
And while the consistency of the fuel coming out of each business should be the same, I think it's safe to say that it's probably not...which doesn't mean they don't all qualify to still be called Top Tier, and meet those applicable standards.
The reality is, since no two fuel brands are the same, it would stand to reason no two Top Tier fuels are the same.
I have 3 Shell stations within close proximity to my home and I consistently make an effort to only fill up at those three...depending which direction I'm travelling in.
To date (almost 17 years) I haven't had an issue with fuel and my vehicles (cars and bikes) get good fuel mileage based on my driving style.
When I hear stories from local residents that use the Costco station, unfortunately the feedback is not so positive. Maybe there is a reason it's cheaper there than anywhere else...but I'm not lining up to find out why.
The roles could easily be reversed and Shell be the suspect fuel provider...it just isn't in this case.
To elaborate on my consistency comment...it was meant to reference the fact that the truck that fills the Costco station near you, won't be the same truck that fills the station near me.
And where both those trucks pick up the fuel to deliver to the station will also be a different place.
My point being that it's up to the refinery to produce the fuel we ultimately put in our tanks, and while you'd like to think that the refineries would be held to a standard across the board if they are supplying Costco with fuel, at the end of the day each one is a business onto itself.
And while the consistency of the fuel coming out of each business should be the same, I think it's safe to say that it's probably not...which doesn't mean they don't all qualify to still be called Top Tier, and meet those applicable standards.
The reality is, since no two fuel brands are the same, it would stand to reason no two Top Tier fuels are the same.
I have 3 Shell stations within close proximity to my home and I consistently make an effort to only fill up at those three...depending which direction I'm travelling in.
To date (almost 17 years) I haven't had an issue with fuel and my vehicles (cars and bikes) get good fuel mileage based on my driving style.
When I hear stories from local residents that use the Costco station, unfortunately the feedback is not so positive. Maybe there is a reason it's cheaper there than anywhere else...but I'm not lining up to find out why.
The roles could easily be reversed and Shell be the suspect fuel provider...it just isn't in this case.
I have no stake in defending Costco... Other than the fact that I shop there and thus sometimes get the gas. Not every tank, but once in a while.
What you said makes sense, and I guess I forget that you're also in Ontario, and I'm in Missouri. So there's even a national border which might affect the experience.
But yeah no two gas stations are alike, regardless of the brand-name. I've heard Costco gas isn't that great before, so maybe there's something to it. And perhaps the higher-stressed 2.0T engine is more likely to encounter conditions in which it won't hold up. However, I'd be more inclined to believe an individual gas station, or in this case, Costco location, is to blame, or the supplier of fuel for that location.
I mean your story of "I only fuel at the local Shell stations and haven't had any issues" is the same as my own saying "I fuel only at Costco and the local Valero stations and haven't had any issues". Which are probably both true. And valid. But, they're anecdotal. I've heard rumors that Valero is not up to par either, but my wife and I have been visiting Valero for several years now without incident. They're also certified Top Tier, but people can't seem to accept it because Valero gas is usually a couple of cents cheaper than the nearest competing station.
I will say this. There's a local Philips 66 station that I don't go to anymore. I could swear the idle was less smooth while my car was running on their fuel. I went there multiple times, so I'm sure it wasn't a fluke. So I do understand the sentiment - do whatever works and don't change unless you have a reason to.
01-27-19, 01:27 AM
What determines Knock Correction Learn Value (KCLV)?
