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I'm sure a Piloteer in Canada can more suredly answer your question. I don't believe that it knows any other temp other than 165.2°F. This temp is still considered below normal engine operating temp. That's why the VCM will not activate.
When this happens on many FI motorcycles for one, my truck also, it operates in Open mode on the ECU management of the ignition and fuel, etc. I haven't read about any ill effects w/ O2 sensors going bad, reading bad, etc. Maybe because it never lets the ECU run in closed mode? I dunno
 

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S-VCM tells the comp your temp is 165.2°F instantly. I don't know of any ill effects of this.
You sure about that? I know VCM Tuner II only locks in at 165.2 once the engine warms up. I've watched it happen.

Also I think people are forgetting that ECT1 doesn't control much except the temp Guage. Most of the engine and fuel parameters that are dependent on coolant temp use readings from the ECT2 sensor.
 

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Thanks,
Oh, I've read and seen all sorts of pictures about it, etc. I agree that the explanations about what it can and does do to an engine are plausable and factual. Why would the oil be extra dark on the cylinders that shut down.
Does the VCM system shut down the spark, and injector at the same time? If it's shut down, why would it 'cook' the oil near it?
Call me lucky, but a few years ago an honest shop was replacing out selenoid thingy and pump for it. They took out the plugs, they all looked so good- they used them again! This was with over 100K on the plugs.

I know the problem exists- just hasn't been a problem for me - yet. I don't think I do/drive any differently than anyone else either. Like many, I do all my own oil changes, and have since it was new. I wouldn't think that would be a factor either.
Before 3rd Gen. Pilots, VCM opens valves, stops fuel and spark. Oil can make its way into the cylinder, coating everything inside (wet black spark plugs) and blowing past the valves. When the cylinder reactivates, any oil in the cylinder is burned, creating more oil deposits. This burning of oil is what can cause catalytic converters to clog and being plagued with the P0420 and P0430 emission codes.
 

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S-VCM tells the comp your temp is 165.2°F instantly. I don't know of any ill effects of this.
I don't think so because my dash temp gauge starts out at ambient then moves up to the 165.2F after driving a few miles. It is capped at 165.2f . I didn't check it with scanner when it was warming up though. No I'll effects so far but winter is approaching and I will soon see if there are any cold start issues.
 

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There is negligible change in air/fuel ratio at 165.2F compared to actual engine temp which is around 180F. Otherwise we would be seeing a larger drop in fuel mileage with the SVCM. From what I have read, the ECT1 signal goes to the PCM and the ECT2 in the lower rad tank, controls the cooling fans. Also if ECT1 detects a high temp it will activate the fans also but I am not sure if that is above 205F or when the warning appears on the dash.
 

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Discussion Starter #26
So does SVCM tell the temperature of the car when it's cold? I wouldn't want it to think it's already at operating temp (or just below it with SVCM), when I just turn the car on. Can anyone verify if the car tells you when the temperature is below 165.2 degrees?
Yes, its showing on my OBDLink App temp raising up to 165.2F.
 

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Before 3rd Gen. Pilots, VCM opens valves, stops fuel and spark. Oil can make its way into the cylinder, coating everything inside (wet black spark plugs) and blowing past the valves. When the cylinder reactivates, any oil in the cylinder is burned, creating more oil deposits. This burning of oil is what can cause catalytic converters to clog and being plagued with the P0420 and P0430 emission codes.
OK. How does it open the valves, as in keep them open so that cylinder freewheels? Does it have some type of selenoid for that when the ECO light comes on. It sure is seamless on my vehicles.
I realize what you are saying has been shown to be true, based on what I've seen and read. But where does that oil make it's way into the cylinder from? Maybe past the piston rings since there is no compression pushing/keeping it down from the combustion?

Please realize, I'm not doubting you, I'm trying to use my reasoning to learn more about this.
 

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OK. How does it open the valves, as in keep them open so that cylinder freewheels? Does it have some type of selenoid for that when the ECO light comes on. It sure is seamless on my vehicles.
Yes, Honda used the Vtec technology for VCM, Variable Cylinder Management (solenoid activated) to boost their fuel economy numbers.
I realize what you are saying has been shown to be true, based on what I've seen and read. But where does that oil make it's way into the cylinder from? Maybe past the piston rings since there is no compression pushing/keeping it down from the combustion?
Correct. The piston pumps oil up into the cylinder.
Please realize, I'm not doubting you, I'm trying to use my reasoning to learn more about this.
Please note that I'm not a snake oil salesman. Like most here, I came here looking for answers and decided to hang out for a month or two. The pictured head above is mine. My engine and experiences are my own.
 

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You sure about that? I know VCM Tuner II only locks in at 165.2 once the engine warms up. I've watched it happen.

Also I think people are forgetting that ECT1 doesn't control much except the temp Guage. Most of the engine and fuel parameters that are dependent on coolant temp use readings from the ECT2 sensor.
I've never seen any temp on my scanner other than 165.2.
 

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I don't think so because my dash temp gauge starts out at ambient then moves up to the 165.2F after driving a few miles. It is capped at 165.2f . I didn't check it with scanner when it was warming up though. No I'll effects so far but winter is approaching and I will soon see if there are any cold start issues.
I'll check this again then.
 

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If you remove your valve cover on your 08, I assure you that you will see the negative effects of VCM on your engine.
The 1st cylinder is #4 which shuts down when VCM activates and eco light comes on. The extra dark oil deposits on the outside pictured here. I'm sure the combustion chamber was double worse.
View attachment 140966
Certainly reminds me of the GM V8>V4 cylinder deactivation debacle. I’m sure Honda electronics have improved but the end result remains the same imo
 

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OK, searched it some. Using 2 different sites- sorry- didn't copy/paste the sources.

Here's what I found.

-That it closes the cylinders- valves closed, no injection, no spark on 3 cylinders.
It states it uses a sliding pin to take away the rocker arm opening the valve, etc.

Here's what I found:

Honda deactivates cylinders using a sliding pin that decouples the rocker arm. The intake and exhaust valves are decoupled and the cylinders are effectively sealed. The compression stroke has no intake and no exhaust; any air compressed is decompressed on the “power” stroke and pumping losses on the deactivated cylinders are eliminated.

and:

The ‘Variable Cylinder Management’ system analyzes throttle opening, vehicle speed, engine speed, and gearing to determine that the car is cruising, and then idles the intake and exhaust valves of the three cylinders in the rear cylinder bank. With zero valve lift, the cylinders are sealed, and no fuel is injected. Pumping losses are thus reduced by as much as 65% and low fuel consumption is realized.

When operating in 3-cylinder mode, engine vibration is reduced by extrapolating vibration from the change in crankshaft rotation speed and sending the information to the ‘active control’ engine mount, which compresses/extends an actuator in same-phase, same-period motion to dampen the engine mount. Similarly, a speaker creates an opposite phase sound or ‘active noise control’, to provide a canceling effect, for a quieter interior which leaves the driver unaware of changes in cylinder activation.

It's kind of what I figured, but didn't realize that from what this says, it has an electronic engine mount too? And a speaker? In the cab?

I'll copy and paste this to a new thread too.

cheers
 

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Here is a copy of the Honda news regarding the new J35 Earthdreams V6 with a good explanation of the VCM system operation. The VCM in the 2nd gen is different and is a two stage system as far as I know.
J35 Earthdreams V6
 

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OK, searched it some. Using 2 different sites- sorry- didn't copy/paste the sources.

Here's what I found.

-That it closes the cylinders- valves closed, no injection, no spark on 3 cylinders.
It states it uses a sliding pin to take away the rocker arm opening the valve, etc.

Here's what I found:

Honda deactivates cylinders using a sliding pin that decouples the rocker arm. The intake and exhaust valves are decoupled and the cylinders are effectively sealed. The compression stroke has no intake and no exhaust; any air compressed is decompressed on the “power” stroke and pumping losses on the deactivated cylinders are eliminated.

and:

The ‘Variable Cylinder Management’ system analyzes throttle opening, vehicle speed, engine speed, and gearing to determine that the car is cruising, and then idles the intake and exhaust valves of the three cylinders in the rear cylinder bank. With zero valve lift, the cylinders are sealed, and no fuel is injected. Pumping losses are thus reduced by as much as 65% and low fuel consumption is realized.

When operating in 3-cylinder mode, engine vibration is reduced by extrapolating vibration from the change in crankshaft rotation speed and sending the information to the ‘active control’ engine mount, which compresses/extends an actuator in same-phase, same-period motion to dampen the engine mount. Similarly, a speaker creates an opposite phase sound or ‘active noise control’, to provide a canceling effect, for a quieter interior which leaves the driver unaware of changes in cylinder activation.

It's kind of what I figured, but didn't realize that from what this says, it has an electronic engine mount too? And a speaker? In the cab?

I'll copy and paste this to a new thread too.

cheers
I believe your info is for 3rd Gen. Older model v6 valves open.
 

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Here is a copy of the Honda news regarding the new J35 Earthdreams V6 with a good explanation of the VCM system operation. The VCM in the 2nd gen is different and is a two stage system as far as I know.
J35 Earthdreams V6
That's good stuff. Also, no sign of the piston rings issue from the VCM 2-style engines. Plenty of them showing up now on post-class action Odysseys (2014-2017). Hoping the VCM 3 direct inject engine has solved most of the old problems. Just motor mounts to worry about (for now)!
 

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I believe your info is for 3rd Gen. Older model v6 valves open.
I haven't read that yet.

Here is a copy of the Honda news regarding the new J35 Earthdreams V6 with a good explanation of the VCM system operation. The VCM in the 2nd gen is different and is a two stage system as far as I know.
J35 Earthdreams V6
This one also states:

'The spark plugs continue to fire in inactive cylinders to minimize plug temperature loss and prevent fouling induced from incomplete combustion during cylinder re-activation. '

So it's NOT shutting the ignition on those cylinders after all.
 

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You sure about that? I know VCM Tuner II only locks in at 165.2 once the engine warms up. I've watched it happen.

Also I think people are forgetting that ECT1 doesn't control much except the temp Guage. Most of the engine and fuel parameters that are dependent on coolant temp use readings from the ECT2 sensor.
I’m assuming you have a VCM tuner 2. So does your car tell the correct temperature on the temp gauge until 165.2? I don’t have an obd2 scanner and I don’t plan on buying one so I want my gauge cluster to properly tell my temperature until it gets to 165.2. Maybe svcm doesn’t have this?

@Nail Grease, so you’re saying your car says it’s at normal temperature as soon as you turn the car on? Even if it’s a cold start? Which vcm disabling device do you use?
 

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