kratedisease

I traded in my 2014 base Z51 automatic for a 2016 Z06 manual.

I noticed that my new Z06 seems not to be shutting cylinders down as indicated on the dash readout . When I had my previous automatic transmission base corvette, it would show me when the V8 would switch over and de-activate cylinders. This new Z06 has yet to deactivate down from V8 mode, even if I am in 5th or 6th gear on the highway very gently barely pressing the gas pedal.

Could it be cause the car only has 700 miles and has not been broken in yet ? I ask if break in would be possibly in the programmed software computer to hold off on de-activation of the cylinders, until the engine is first broken in ? just speculation on my part - guessing ? .

OR, do the Z06 vetts or manual transmission vetts not have this de-activation of cylinder feature ? .

Just curious. Thanks for any input

cowboy casey

Your manual will only go into V4 mode when in Eco the way the Auto should have been

Thanks Jerry and others for pointing that out, I am new to manual and could have sworn I read on the forum Weather mode also went into V4 mode... (NOT) Weather mode

dvilin

^^^^^Agree with the M7 you must put it into Eco mode.

JK 23112

I have a 2017 Stingray with the 7spd manual and it must be in WEATHER or ECO mode for the "V4" feature to kick in. My girlfriend has a 2019 Stingray with the 8spd automatic and it goes into "V4" all the time on its own. (I agree with the post above that this feature should be the same in the automatic cars as it is with the manuals -- ECO or WEATHER mode only for the V4.)

JK 23112

On a related note, I do have a question about the "V4" mode. Does the engine's computer shut down the same four cylinders every time - or does the computer continually change the ones that are deactivated? If a cylinder is deactivated, is it running "dry" with no fuel (just air) entering the combustion chamber? Is all of the lubrication still being provided? I have heard that Chevrolet has had some issues with the AFM system in the Silverado truck engines (also small-block V8s).

Just curious and wondering if anyone in the Corvette Forum Brain Trust had any insight.

eboggs_jkvl

Same 4 shut down for the V4. Special valves train parts are involved and only apply to specific cylinders.

When AFM initiates, the engine turns the 6.2L V8 into a 3.1L V4, shutting down cylinders 1, 4, 6 and 7, and firing only cylinders 8, 2, 5 and 3 in that order.

Otherwise, the complete firing order is 1, 8, 7, 2, 6, 5, 4, 3.

Elmer

JerryU

Hmm, it only goes to V4 when in ECO Mode, where my 2 year old Grand Sport has never been! States that in the Owner's Manual. Another advantage of an M7!

It does NOT go to V4 in Weather mode in my GS nor did it in my 2014 Z51 M7. I do use Weather mode when it's below 45F and would NOT want the change in power that I don't control with my foot!

JerryU

Adding to Elmer's post, you may find this of interest. It's not so simple and no issues raised on the Forum about technical problems related to wear or oiling, nor should there be:

"Cylinder deactivation is accomplished by not allowing the intake and exhaust valves to open on the selected cylinders by using special valve lifters. The deactivation lifters contain spring loaded locking pins that connect the internal pin housing of the lifter to the outer housing. The pin housing contains the lifter plunger and pushrod seat which interfaces with the pushrod. The outer housing contacts the camshaft lobe through a roller. During V8 mode, the locking pins are pushed outward by spring force, locking the pin housing and outer housing together causing the lifter to function as a normal lifter. When V4 mode is commanded ON, the locking pins are pushed inward with engine oil pressure directed from the valve lifter oil manifold (VLOM) assembly solenoids. When the lifter pin housing is unlocked from the outer housing, the internal pin housing will remain stationary, while the outer housing will move with the profile of the camshaft lobe, which results in the valve remaining closed. One VLOM solenoid controls both the intake and exhaust valves for each deactivating cylinder. There are 2 distinct oil passages going to each cylinder deactivation lifter bore, one for the hydraulic lash-adjusting feature of the lifter, and one for controlling the locking pins used for cylinder deactivation.

Although both intake and exhaust valve lifters are controlled by the same solenoid in the VLOM, the intake and exhaust valves do not become deactivated at the same time. Cylinder deactivation is timed so that the cylinder is on an intake event. During an intake event, the intake cam lobe is pushing the valve lifter upwards to open the intake valve against the force of the valve spring. The force exerted by the valve spring is acting on the side of the lifter locking pins, preventing them from moving until the intake valve has closed. When the intake valve lifter reaches the base circle of the camshaft lobe, the valve spring force is reduced, allowing the locking pins to move, deactivating the intake valve. However, when cylinder deactivation is commanded ON, the exhaust valve for the deactivated cylinder is in the closed position, allowing the locking pins on the valve lifter to move immediately, and deactivate the exhaust valve.

By deactivating the exhaust valve first, this allows the capture of a burnt air/fuel charge or exhaust gas charge in the combustion chamber. The capture of exhaust gases in the combustion chamber will contribute to a reduction in oil consumption, noise and vibration levels, and exhaust emissions when operating in V4 mode. During the transition from V8 to V4 mode, the fuel injectors will be turned OFF on the deactivated cylinders. The ignition system secondary voltage or spark is still present across the spark plug electrodes on the deactivated cylinders. If all enabling conditions are met and maintained for cylinder deactivation operation, the ECM calibrations will limit cylinder deactivation to a cycle time of 10 minutes in V4 mode, and then return to V8 mode for 1 minute.

Cylinder Deactivation (Active Fuel Management)

General Motors Active Fuel Management engine control system has the ability, under certain light load driving conditions, to provide maximum fuel economy by deactivating 4 of the engines 8 cylinders. The engine will normally operate on 8 cylinders in V8 mode during starting, idling, and medium or heavy throttle conditions. When commanded ON, the engine control module (ECM) will direct the active fuel management system and deactivate cylinders 1 and 7 on the left bank and cylinders 4 and 6 on the right bank, forcing V4 mode.

Active Fuel Management Valve Lifters

When operating in V8 mode, the active fuel management valve lifters function similar to the non-active fuel management valve lifters. The active fuel management oil manifold solenoids are in the closed position, with no pressurized oil directed to the valve lifters. The pushrod travels upward and downward to actuate the rocker arm and valve. The spring loaded locking pins of the lifter are extended outward and mechanically lock the pin housing to the outer body of the valve lifter.

When the active fuel management system is commanded ON, the ECM will direct the solenoids of the oil manifold to open and direct pressurized oil to the valve lifters. Oil travels through the valve lifter oil manifold and engine block oil galleries and enters the inlet port of the valve lifter.

When operating in V4 mode, pressurized oil forces the locking pins inward. The pushrod remains in a constant position and does not travel upward and downward. The outer body of the lifter moves upward and downward independently from the pin housing. The valve lifter spring retains tension on the valve train components to eliminate valve train noise.

When the active fuel management system is commanded OFF, the ECM directs the solenoids of the oil manifold to close, stopping the flow of pressurized oil to the valve lifters. The oil pressure within the lifter will decrease and the locking pins will move outward to mechanically lock the pin housing and outer body."

JK 23112

Okay......come to think of it I never drove my car in "WEATHER" mode -- so maybe the deactivation won't work in that setting. I know it works in the "ECO" mode, as the 'V4' indicator glows a bright green. It won't do it on Touring, Sport or Track mode (again, I have the manual), though. My girlfriend's car is an automatic and the 'V4' indicator comes on almost constantly in E, T or S modes. She has never driven it with the Tr mode at all - as it only has 300 miles on it so far.

THANKS VERY MUCH for the information. I am still not sure of the long-term effect of the cylinder deactivation feature. It seems like something else to go wrong, but maybe it will work flawlessly for the life of the car. I honestly don't know.

JK 23112

Thank you, Elmer! Very interesting information, sir.

Null Pointer

Thanks Jerry for confirming that it only goes to V4 in ECO on a manual shift. My 2019 owner manual states that on Page 185. Weather mode keeps all 8 cylinders active in the cars equipped with a manual transmission. Which reminds me that I need to post my Range device for sale now that I no longer drive an A8 equipped car.

Thunder22

I have to do the same thing, I keep putting it off for some reason

kratedisease

Thank you so kindly for the reply, wondering what was up, you explained it !

GARYFINN

The only way my car will ever see the V4 mode is by accident.Its a Corvette people.

z51vett

DOD sucks wiped out my cam 3 year old Z06 13400 miles 6 weeks in shop drop front cradle out pulled everything out but crank rods and Pistons.
z51vett
Doug

KenHorse

Uhhhh no.

In an M7, only when in ECO mode. WEATHER mode does not activate AFM

JK 23112

.

Yeah, I saw that in an earlier post. I've never even driven mine in the "WEATHER" mode, so I was just going on what others had mentioned about it. Since mine is a stick-shift, I can avoid the V4 issue by not selecting "ECO" when I drive it.

My girlfriend has a 2019 with the A8 and hers goes into V4 mode in Eco, Touring and Sport mode (not sure about Weather or Track).

djnice

When having an honest off the record conversation with gm mechanic he tells me there are lots of occurrences with collapsed lifters in any of the V4 mode engines.

eboggs_jkvl

The A6/A8 will go into V4 mode in all settings. The only way to keep it from switching to V4 is to drive with it in "M" and use the paddles. When in "M", no V4 mode while driving.

Elmer

Internets_Ninja

2017 Manual Z06 here as well. Any of you guys notice that at highway speeds(70mph+) in 7th gear the car pretty much never goes into V4 mode unless you are decelerating? I had a manual 2015 Z51 before this and it would go into V4 mode easily in 7th gear even at 80mph+. In the Z06 ECO mode is pretty useless on the highway from my experience. It does work well around town though but I never use it because I don't like the lag when you have to keep up with dynamic traffic patterns.