Question V4 to V8 noise under light acceleration

[Jeffer2013]

a range should come standard or be a option on all c7
way better than most options to protect the engine after the warranty expires
best mod ever
did I mention EVER

 

[YFCvii]

there is a place in Canada that sells them
will not post as they are not a sponsor

Maybe it's OK to just mention a resource without actually endorsing it? Leaving it up to those reading for going further.
It would be seen as only helping other members on these Forums regardless of whether any member financially or otherwise supports ccf.
Hey ... it's no big deal as I am sure you would disclose this resource ... if asked by anyone in a personal message

Fortunately, my two A8's do not have this issue so I will not be lining up for the device but I am almost
certain the V4/V8 feature has quite a bit to do with my sustained 6.6-6.9/100km consumption when just cruising
from A to B on a rather boring straight highway.

 

[WPGZ06]

Most people, like myself, do not have issues with hesitation but to stop the car from going into V4 mode at all. Other reasons to get the Range.

If the OP gets the Range device I would recommend unplugging it if you leaving car sitting for long stretches. Some people have reported battery drain if it is sitting for long periods without battery tender hooked up.

GM would never disable that option, they put it on the car so gas mileage would increase, they could tune it out but they never would.

 

[YFCvii]

... GM would never disable that option, they put it on the car so gas mileage would increase, they could tune it out but they never would.

thinking about that .... this might be a feature that keeps new-vehicle GM buyers from being assessed a "gas guzzler tax" by the Government(s).
Therefore mandated that GM not provide/support an easy way to disable it as excessive buyer-taxes would definitely affect marketability.
Even my 6.2l Sierra has a variable system and I am starting to appreciate it when comparing to the Hummer that requires and uses
its dual-fuel tank feature.

... so going back to the OP issue, I was servicing at the YYC Carter Dealership at the time of reading this morning and
the tech person here suggests to discuss the issue with another Dealership to find one that has maybe faced it already.

 

[cdnrx1]

Just an update. Talked to the dealer yesterday and the told me they can not disable the V4 to V8 option and they also directed me to the aftermarket Range unit. Will look into it. Any problems with this unit once you plug it into the car??

Hey Jerry:

Interesting response from your dealer in that they actually recommended the Range device. Hopefully that means that they will not associate it with any possible future warranty related issues. If you get one it's a good practice to remove it and run the car for 200-300 kl's before taking it in for service. This will eliminate any trace of code.

It's important to understand what the Range device is, what it will do, and what it will not do. It is an AFM (Active Fuel Management) disabler. When attached to the OBD II port it sends a continuous string of code to the ECU telling it not to switch from V8 to V4 mode. The latest version for the C7, I believe, is V8.6R1. This is important because prior versions, if left attached, would create a slight parasitic draw on the battery and could, over time, drain it flat. The latest version is safe to leave in the port without risk of discharge. If left in the OBD II port ongoing it will prevent OnStar from creating it's monthly report. They still send it but advise that they cannot obtain the information because there is another device occupying the OBD II port. I got a few of these during the first year that I used the Range device.

It will not change, replace or otherwise modify any factory ECU settings. As such, it should not affect the vehicle as relates to the original warranties. Some dealers have stated otherwise, hence the need to remove it prior to taking it in for service.

It will not change or improve the vehicle's performance. The code within the device is strictly "command" only and does not replace any hard coding in the ECU. Some people have reported smoother / quicker shifts but the Range device has no capability to achieve this.

Overall it's a good tool if your objective is to prevent the switch from V8 to V4 mode, it works perfectly. I used mine for about a year but removed it as I use the manual shift mode almost exclusively. I will shift to automatic occasionally just to check for "shudder" but so far, so good.

Best regards
Ross

 

[WPGZ06]

thinking about that .... this might be a feature that keeps new-vehicle GM buyers from being assessed a "gas guzzler tax" by the Government(s).
Therefore mandated that GM not provide/support an easy way to disable it as excessive buyer-taxes would definitely affect marketability.
Even my 6.2l Sierra has a variable system and I am starting to appreciate it when comparing to the Hummer that requires and uses
its dual-fuel tank feature.

... so going back to the OP issue, I was servicing at the YYC Carter Dealership at the time of reading this morning and
the tech person here suggests to discuss the issue with another Dealership to find one that has maybe faced it already.

That is what I expect as well, and I too have the 6.2 with it. Cannot say I mind it for the mileage but I despise the auto shutoff, I'm going to get the alternate Range device to disable that feature once they market it for the newer model 1500's

 

[Rruuff Day]

there is a place in Canada that sells them
will not post as they are not a sponsor

Naming a supplier is no problem Jeff. It's the suppliers that join the forum just to advertise their goods that we frown on. unless they become a sponsor. No post their name if you like.

 

[YFCvii]

That is what I expect as well, and I too have the 6.2 with it. Cannot say I mind it for the mileage but I despise the auto shutoff, I'm going to get the alternate Range device to disable that feature once they market it for the newer model 1500's

Agree … have to live with the shut off too … just hate how it reengages when starting back up to accelerate. So I find I let off the brake slightly to get the engine going before the light goes green again. Oh well

Yes it can be turned off but you have to do it everytime you start up … so I have to choose the best of the worse with some features. I’m just not a fan of some after-market add ons.

 

[Etid]

Anyone having this problem. It is like a rattle and you can hear a noise as it changes to the V8 mode from the V4 mode.

Try Petrocan 94 octane or get some high test ethanol free gas.

 

[LE BARON]

Running in Sport or Track mode cuts out a lot of the situations where the ECM shifts to 4 cyl.
Personally have not had the problem mentioned and I run in Tour mode most to the time so it will switch to 4cyl when I am just putting along. Very slight effect when I stomp it although it is noticible. No noise from mine.

 

[WPGZ06]

Agree … have to live with the shut off too … just hate how it reengages when starting back up to accelerate. So I find I let off the brake slightly to get the engine going before the light goes green again. Oh well

Yes it can be turned off but you have to do it everytime you start up … so I have to choose the best of the worse with some features. I’m just not a fan of some after-market add ons.

Well Range does make the disabler for the auto-shutoff but it does not work for the newest models yet, but once they come out with one I'm grabbing it, then it be simply plugged in all the time and never have to deal with it.
They also make another device but then I have to pull open the dash to install it, I haven't gotten annoyed enough yet to go that route...yet lol

 

[Vanguard2001]

Interesting thread. My 2017 M7 coupe would shudder when transitioning to 4 cylinders but only for a couple of seconds. The 2019 GS A8 vert does not, it is completely unnoticeable. Sometimes I keep the dash display in the mode where it shows the number of active cylinders just to see when it happens. The gas consumption in 4 cylinder mode is excellent on a highway drive. When moving about the city I usually use manual mode.

 

[kingofthehill]

Thanks. The car is still under warranty and I am trying to get opinions to submit to the dealer. They seem to be at a loss as to how to correct my problem.

Why in the world would a person buy a vett then run on four makes no sense.

 

[YFCvii]

Why in the world would a person buy a vett then run on four makes no sense.

You thinking there is a choice? … there isn’t and it is something rather superficial to me.
Smooth and transparent transition between is what matters and sadly the OP does not experience it.
My variable Sierra and 4/8 Vette goes to 4 (or variable) when it finds I wont even know the difference … and I don’t.
If it finds I save some coffee money at the pumps, maybe it allows me to also buy the coffee for the fella in the C3 on the cruise with me

 

[kingofthehill]

You thinking there is a choice? … there isn’t and it is something rather superficial to me. Smooth and transparent transition between is what matters and sadly the OP does not experience it. My variable Sierra and 4/8 Vette goes to 4 (or variable) when it finds I wont even know the difference … and I don’t. If it finds I save some coffee money at the pumps, maybe it allows me to also buy the coffee for the fella in the C3 on the cruise with me

Well with your mind set . Get a bike and pedal around then you got coin for lunch too.

 

[YFCvii]

Well with your mind set . Get a bike and pedal around then you got coin for lunch too.

All good with a bike when one has no choice … when missing my point … I’m good with that too

When 8 is needed it's there for me ... but I am only offering a coffee and not a lunch ... LOL

 

[kingofthehill]

All good with a bike when one has no choice … when missing my point … I’m good with that too

When 8 is needed it's there for me ... but I am only offering a coffee and not a lunch ... LOL

Glad you got a sense of humour.

 

[LE BARON]

When I took the run out to MITM the fuel consumption, so little for the size of the engine, surprised me. Don't know how often I was in "4" mode as cruising was quite often in the 125-175 area. Had to make good time. 8hrs first day, 11hrs second day and a short 7 hrs cruise from T-Bay to Winnipeg.

 

[Jerrys Vette]

I appreciate all the great info. The choice is mine to make if I buy the Range devise because the annoying part is always at low speeds and going uphill. Other than that the car works perfect, so I have to decide to spend the 300 bucks or to drive the car on flat roads only. (HA HA) This has been a great learning experience and I am much appreciative of all the input.

 

[Vanguard2001]

While in A7 mode and approaching a hill, use the paddle to downshift 1 gear. The 4 mode will switch to 8 immediately. The paddles are a great driving tool even when the gear selector is in full auto mode. Use the left paddle to downshift progressively coming into a stop with track exhaust turned on - who-hoo what a sound. Approaching a stop or fast turn, hold the downshift paddle for 2 seconds and the tranny moves to the lowest gear possible for that speed. Again - what a thrilling sound and feel. Hold the upshift paddle for 2 seconds and the tranny returns to full auto mode. Lots to play with there and adds to the JOY of driving the A8.