Poolman

Just getting my feet wet here. Question, has anyone here tried one of the following on a 2015 model RDX ?

https://www.vcmtuner.com/

jjrphs

In my opinion, the Honda 3.5L V6 engine is solid...but the VCM system Honda puts on these engines leaves a lot to be desired. Earlier iterations of this system caused a lot of problems from driveability to unusually high oil consumption to damaged engines. The proof in the pudding is the class action law suit Honda lost regarding this issue.

Will your engine make it through it's lifetime without harm or other issues caused by this system? Maybe or maybe not. I chose not to take that risk and installed a VCM disable device. In picking my particular device, because there are several on the market...I chose the S-VCM Controller because there's no change or adjustment of a resister based on outside temp and IMO, it's the better device to have installed if the vehicle were to have a (rare) overheat occurrence and also because I believe it was the best choice for me.

Disabling VCM has eliminated the shudder associated with VCM activation/deactivation on my wife's 13 RDX and driveability and responsiveness has improved with all 6 cylinders running all the time.

Poolman

Had something similar , but in just a different car, That had to be combated. Got almost 400k on that ride, and wouldn't have gotten there without preemptive action. Have studied this for only a few hours this evening, and from what I have come up with, the approach you have taken, will be the same as the one for the new used car in the carport. Not going to take the chance that they got it right. Besides this shouldn't hurt anything except a mile or so a gallon, and on the plus side, the engine will last longer.

Poolman

Had this thought come nagging me this morning. There is a sensor that tells the ecu that the engine is cold in the AM and rich-ens the fuel mixture for a cold start, As the engine warms up the fuel mixture is leaned for normal driving. Is the sensor the VCM controller is hooked into, the same sensor that gives the fuel mixture signal for the ECU ? If it is, wouldn't that keep the fuel mixture rich all the time?

Tech

So why doesn't Honda/Acura deactivate the VCM system when asked to do so? I am sure it can simply be done with their software.

Or are they so worried that fuel consumption will be much higher than advertised and they will get sued?

Here is the info on the S-VCM Controller that I got off their ebay site. Not sure I want anything since I cannot tell whether the VCM has been activated or not. No shudder, nothing.

Tech

The docx in my previous post didn't work, so here is the attachment again.

jjrphs

I'm assuming the same reason why there isn't a switch on the dash to turn it off...that if Honda/Acura offered to deactivate VCM on those vehicles so equipped, it would nullify their CAFE number.

VCM is just a strategy Honda (and Chevrolet) employed to wring the last couple MPGs of efficiency out of their larger engines. I think one has to ask themselves if VCM was so good...why didn't Honda offer it initially with the roll out of the powerplant 20 years ago, rather than waiting until CAFE standards required they tack on this system to their 3.5 V6 powerplant to meet standards.

I have close to a combined 250k miles experience in 2 previous vehicles which had earlier versions VCM...a 2008 Odyssey and 2011 Pilot. The version of VCM in these 2 vehicles was definitely not refined and caused driveability issues along with oil consumption problems. I lived with those issues in the Odyssey till we sold it...I installed the S-VCM Controller in the 11 Pilot about a month before we sold it. It made a difference in the driveability of that Pilot to the extent that when I bought our RDX....I pulled the S-VCM from the Pilot and put it into the RDX. I also purchased a cheaper (fixed resister) version of a VCM deactivation device to install into the Pilot for it's resale.

I bought our 13 RDX with 55k miles...it had the classic Honda symptoms of shuddering and juddering up thru the gears and I could feel it switching in and out of VCM on the highway. I did 2 things to our RDX at the same time...a x3 drain/fill with MaxLife Dex/Merc Full Synthetic ATF and installed the S-VCM Controller. The RDX was transformed into the refined driving experience it should be.

Bottom line...I'm not trying to suggest or push anyone into installing a VCM deactivation device. My personal experience however, is such that I'm a firm believer in having all 6 cylinders running all the time. It was the best choice for me and more than worth the money I paid...it may not be for everyone.

Poolman

I'm sold on this idea. At the same time, does anyone know the answer to the question that I put forth on post #4 ?

Tech

What did it do to the fuel consumption based on numerous fill-ups?

Poolman

What I would be most interested in, is short and long term fuel trim readings, after this device was hooked in line. Shouldn't take long for the OBC to adjust. Say a few days after the part was hooked in, the readings would give the info that would be needed.

jjrphs

While I'm no expert, it's my understanding is there is no issue with the ECU's perceived coolant temp keeping the fuel mixture in "rich" mode or the EGR open...that the VCM disable device only "tricks" the ECU just enough such that VCM does not engage, but ECU still "sees" the engine up to operating temp.

Because I installed the S-VCM Controller immediately into our 13 RDX after purchase...I have no comparative before/after MPG data with our RDX.

In the short time (1 month) it was installed in our Pilot, I logged <1 MPG difference with S-VCM Controller vs not. There's plenty of others who have installed VCM disable devices in their Odyessys, Pilots and 2nd Gen Ridgelines...of those who've posted data that I've read, it appears that the greatest comparative difference was less than 2 MPG less fuel efficiency. For myself, the modest MPG reduction is a small price to pay for turning off this system with its potential long-term driveability and engine issues.

Poolman

I have one on order. Should be here in about a week. If anyone has a code reader that has the ability to read long term fuel trims, would like to know what readings they are getting. I'm not sure as of yet, where to hook my reader into my newest ride. Is it under the dash near the floor board?

DvM

Hi . i just ordered the s-vcm device from eBay and have received the device. It came with a single sheet of instructions but the picture on it does not correspond to my car. I will be installing it on a 2018 RDX Elite. Had anyone installed this device on a 2016+ RDX ? could you please post a pic regarding which port on the engine i am to use to fix the device to. Thank you.

DvM

Hi . i just ordered the s-vcm device from eBay and have received the device. It came with a single sheet of instructions but the picture on it does not correspond to my car. I will be installing it on a 2018 RDX Elite. Had anyone installed this device on a 2016+ RDX ? could you please post a pic regarding which port on the engine i am to use to fix the device to. Thank you.

Poolman

It's to be hooked to the temp sensor. That's about as simple as it gets. Mine is a 2015 model , and the hook up is just under the cover on the right side of the engine.Is the 2018 engine that different from the 2015 engine.?

jjrphs

What Poolman said.

Here's a video of the installation of a different VCM disable device into a Pilot where installation is essentially the same with regard to location and connection. With this video and the S-VCM Controller specific instructions, you should not have any problems.

DvM

Thanks for all the replies .As you said, its as simple as it could be. The video you posted really helped .
Ride quality seems a little smoother, especially when slowing down at the lights. Not much else noted at this time.

Poolman

Here I am telling others how simple this is , and I can't get the damn clip off of the sensor to install mine. It's just squeeze and pull,right. Mines stuck on there

DvM

Hey. It is a pain to get the clip off. Just need to apply pressure to the top-part of the clip until you hear a "loud click" and then the plug should just slide off. if it dosent slide off easily, it means its still clipped on. Helps if you have smaller hands to reach the sensor better. hope this helps.

Poolman

Okay, got the part hooked up. Before install, I cranked the car and rolled it back about 20 ft so as to have it out in the nice warm sun. Did the work, cranked the car, then the following warnings came up. Check emission system check VSC, or traction system, Check Power steering system,Check hill assist system. So the dash lit up like a Christmas tree LOL.. I removed the part and set every thing back the way it was, but the lights didn't go away. I don't have my code reader with me. Can I erase these codes with my reader?

Poolman

Retrieved my scanner and have set the code situation and remedied that problem. Hadn't moved the car for 3 days before the install this AM. Did move it back a few feet to get it out in the sun, but the engine was cold. Only code that came out on the scanner was incorrect engine temp code, and the other foolishness went away. I'll try again when the engine is cooled down enough to get my hands back in to the sensor connector.

DvM

Didnt get any lights or error codes so far .I installed the s-vcm when the engine was stone cold after letting it sit in the garage overnight. Will update if I do see any errors or codes. To be honest, I dont know if the device is really doing anything. Is there anyway to be certain that all six cylinders are working?

Poolman

The VCM to my understanding doesn't really actuate until you let up off the gas peddle. When your slowing down, do you still feel like the trans is dropping to a lower gear? Feel like that will be gone with the install of this product. There's about 3 k miles to go before I take it back to the dealership for a free oil change. Believe when that has happened, will give it a go again.

DvM

When slowing down for a light or traffic, the trans does drop to a lower gear and there is a very slight jerk due to engine braking i guess from the automatic downshift. I expect this is normal, despite VCM deactivation? Im only at 2100 kms so far, so the engine is still being broken in. Very happy with the ride so far.

@Poolman. How has your experience been since the install? Thanks.

Poolman

Gonna wait until the oil change at the dealership, before I give it another go.

firstRDX

This is a good question. If this S-VCM is sending a false signal to the ECU about the current engine temp will the emission / fuel system stay open loop (run rich). I'm not sure what the normal temp threshold is for the ECU to switch from open loop to closed loop fuel management ~ 195 to 205. Maybe I'm all wrong on how the ECU code works and controls the fuel management.

jjrphs

Normal operating temps would probably be something like 180 to 210 degrees. Threshold temp for closed loop operation will be significantly lower...more like 130 to 150 degrees. As I understand it, VCM will engage (under the right operating conditions) when the ECT #1 sensor signals the ECU the coolant temp is 167 degrees or greater. VCM disable devices "change" that ECT #1 signal going to the ECU to indicate just under 167 degrees.

From what I understand there are parameters other than coolant temp which determine if the engine is in open or closed loop operation...O2 sensor temp, engine rpm, etc. It is also my understanding that once the O2 sensor is up to temp...it is given command authority over fuel control and the ECT senor(s) input has little to no influence.

Finally and the bottom line is if the ECU sees all other operating parameters as "normal," but the ECT #1 signal indicates a temp below closed loop threshold...the ECU will set a fault code and the CEL will come on while the engine is still operating in closed loop mode. With the fixed-resistor based disable devices, this can happen if a "too cold" resistor is installed...this cannot happen with the logic-based operation of the S-VCM Controller.

Poolman

I had asked the same question early on. Best way to determine an answer, would have someone who has installed the part, use a scanner that can give up long term fuel trims , then get back to us. My scanner can do that, but it's going to be a while before I make the install again.

jjrphs

Disabling VCM to run on all 6 cylinders all the time will yield a slight to imperceptible lower fuel economy. Running in open-loop continuously would yield significantly lower fuel economy that should be easily noticed without electronic monitoring.

kp2g

I just recently purchased a 2018 RDX and I was wondering the same thing about the fuel.
Were you ever able to check after finishing your install?

trcollins59

2014 RDX Tech FWD, before VCM disabled 23 mpg, after VCM disabled 21.5 mpg for our mixed city/highway driving.
All highway for our usual 700 mile trip has decreased from 26 to 25 mpg.
I prefer the smooth engine performance having the VCM disabled.

altair47

You don't need an VCM in such driving conditions. The main difference is felt on cruise control at 55-65 mph.

Michaelgrimmer

Does anyone know how to disable the vcm manually on a 24 acura rdx without getting the disabler

t0md0

Wait am I reading this right? I have 2013 RDX and I've always noticed that when coming to a red light that the engine brakes from down shifting but I thought it was the transmission?? It is a bit annoying tbh especially coming from my 4 speed Mazda prior that didn't do it (or wasn't noticable) but I guess I'm sorta used to it now (still a little annoying lol)... Are you telling me that's the VCM doing that?

I did notice some shift shock when I first purchased my car in 2017 as a CPO but was able to send it in for warranty work although I think there was a TSB for it. They updated the software and did a transmission fluid change. Not sure if this the shudder or judder that some people talk about with the VCM but this resolved my shift shock.

I didn't know people were having issues with VCM but now you guys got me worried.. I honestly don't think I'm having aany issues other than the down shifting I mentioned. Car has 90K miles. Bought with about 53K. Oil levels seem ok. I never felt the VCM kick on while driving on the hwy ever. Then again I usually go 70-80mph. When does it kick on?

dtownfb

The VCM only kicks in at steady highway speeds. As Altair47 wrote, between 55-65 mph. The downshifting you feel is how the transmission behaves.

t0md0

I'm curious why you think VCM tuner would remove the downshifting that the transmission does when coming to a stop or slowing down? According to a couple people here it turns on around 55-65mph.

Poolman

Well curious , when I bought the car and experienced the braking of the transmission and all, I really thought that braking was an indication of the VCM activating. I had just purchased the vehicle and had not ever experienced that bogging (for the want of another word)
before and , was really wanting the controller to eliminate that problem. Well live and learn.

t0md0

So did you ever install the VCM after all? Also, did it get rid of the transmission braking like you initially thought it would? My guess is no because like you said, it's actually the transmission and not VCM. And if you did install it, what are your thoughts on it?

jjrphs

Though it was never an issue with my 13 RDX...I do recall several owners commenting that their RDX transmission's "unsettled behavior" experienced while slowing down or under braking was completely resolved with the addition of a VCM deactivation device. I just assumed their transmission issue was a by-product of the VCM system engaging / disengaging under the light or diminishing load while slowing down...not unlike the lighter load of cruising on the interstate.

Poolman

Yes installed back in 2018. Worked great and would advise others to use the product. No it didn't stop the trans from downshifting when slowing down , but it noticeably
improve it somewhat. The unit was recently removed and replaced with a new unit, after finding the old one had stop working. If you don't have one on your ride , it's your choice , but for me I will continue to install one on what ever honda vehicle I ever own that could use one. Regards