GazUK

lastcowboy

yep i agree , ....lets all go out and buy a corvette so we can save gas ?
if i wanted to save gas i would buy a kia

Glen e

Nobody cares what you buy, every car with AFM helps a mfr with EPA, the afm is on the cars to help gm MEET or exceed the fleet average. With AFM, they can increase performance. You dont like it, TURN IT OFF iwith a range device for autos or stay out of eco with a manual.

W88fixer

Geeze, how many have had an issue with AFM? Very few. Zero problems with my C7, goes away instantly when more power is needed. Zero problems with my 2009 Pontiac G8GT which is even more transparent than the C7.

GM needs all it can get to meet corporate CAFE standards. Don

Jay_Davis

I tried ECO mode and it was pretty seamless, as a matter of fact it seemed to pop out of V4 mode at any touch of the gas pedal. I have a '15 with the A8, so its possible they've improved it a little.

LIE2ME

2014 Non Z51 vert, about 5000 miles on the clock. Earlier today, I had to accelerate hard to pass a line of slow moving trucks. I was hitting the gas pretty hard and the car was delivering torque magnificently, when suddenly she bogged down. The RPMs dropped and the car began to slow. After maybe 2-3 seconds (my pressure of my foot on the gas pedal never changed) , the car suddenly resumed its rapid (and expected) increase in speed and I completed my maneuver with no further problems.

JerriVette

Sounds like traction control/active handling kicked in.

Skid Row Joe

GM is notorious for experimenting with their new releases on their new buyers.

This Chevrolet Corvette 4 cylinder firing to 8 cylinder firing reminds me of the /FAILED 4 cyl. / 6 cyl. / 8 cylinders firing Cadillac V8 engine sprung on the GM new buyers almost 35 years ago.

You guys reporting problems with your Chevrolets are the 2014/2015 GM guinea pigs.

Nothing's changed since I was a young man buying Cadillacs in the '70s.

Tommy D

It is very easy to check you will see a yellow light with a small car & tire marks on the lower portion of the speedo light up.

lastcowboy

yep.....you got that right.

Mike Mercury

Now that my A8 '15 has gone past the 500 mile break-in mark; I am noticing something similar.

I brought up a screen that shows instant MPG and whether the car is in 4 or 8 cyl mode... and this "feeling" does coincide with the switch from 4 cyl into 8 cyl mode.

Now that I realize what's happening, our daily drivers do something similar; though with a slightly different feel. I'm kinda getting used to it now.


same here

BigJoe

I have experienced a slight hesitation with my A6 several times under one specific situation. When approaching a red traffic signal and slowing down to 10-15 mph preparing to stop and suddenly the light goes green. As soon as I give it some gas (normal driving here, not heavy throttle) it bogs down for a second or two. I have always thought it was just hunting for the correct gear but maybe is it something else? I don't know. I never feel any bogging down under any other scenario.
I also watched as the car switched from 4 to 8 and back many times and even when I know it just happened I can't feel it.

Tommy D

Since you have the 8 speed and we have the A6, I think that what we are all feeling is the software.

The transition from 4 to 8 cyl mode on the auto is not as seamless as we all thought. There are driving conditions as previously posted whereas you can "feel" the change, be it 4 to 8 and the corresponding change in engine or trans inputs by the software.

Just as the C6 had torque management which reduced the throttle imputs (even though it was floored) the C7 most likely has the something similar. Possibly more invasive as the car goes from 4 to 8 cyl mode

My concern is that while all of us experience some hesitation there are times when that hesitation is way too long.

69L79

Now, that is a very scary scenario. Has that incident affected or will affect the way you drive, i.e., hanging out there on a two lane road, passing a line of cars/trucks?

lastcowboy

yep.. tryied to talk about this same prob. on this forum and was met with people saying they felt nothing . i for one am glad people are now talking about this prob. and some of the dangers it brings with it
and pos. damage down the road to our cars . my hope is tha gm will
address this prob. before it gets someone killed

Mike Mercury

it's most noticeable to me when...

driving at a constant speed in 4 cyl mode. Need to accelerate slightly; just enough to kick it out of 4cyl mode... but not enough to demand a downshift.

cberistain

2014 A6 .. when driving at a steady speed.... say 40mph and I tromp on the gas, there is a pause .. kinda like there is a turbocharger and it needs time to spool up .. then the car just flies ... I think this is what really is happening: the engine is only turning say 1500rpm and the transmission is most likely in 5th gear ... and that gear is just too high so the transmission shifts down.

I just ran an experiment ... driving at steady 40mph .. and just before tromping on the gas, I downshifted ... no delay at all ..

Then .. again driving at around a steady of 40mph .. I shifted to "manual" and it was in the fifth gear ... I tromped on the gas and the engine just lugged .. just could not accelerate. guess at low rpm, the engine has no torque?

and a question .. when does the transmission finally shift into 6th gear? and if it is in 6th gear and I move the shift lever to manual mode, will it stay in 6th and automatically drop to 5th?

thanks
charlie

ETHYL

Mine acts like yours. No problems. VIN # range 22000

Jaykoh-Z51

Hey fellas...brand new member here. Don't have my vette yet. Doing lots of research and listening to you fine gentlemen on your experiences.

I can, however, contribute to this auto tranny discussion. I have 2014 jeep Grand Cherokee SRT. For those that don't know, it has a 6.4L hemi and gets about 470hp and 470tq. 0-60 times between 4.0-4.6. The 2014s have an 8speed auto that will also shut down 4cylinders.

The SRT has NO lag or lugging at all. I'll be at cruise speed..40, 60, 80, put the hammer down and BOOM...instant power and acceleration with very quick shifts. I had assumed the A6 and A8 C7s would be similar. After reading this thread and a few other comments, makes me lean to the M7.

The "issues" or complaints appear to be purely software related. The SRT had an annoying down shift lurching thing for a while when slowing down for a red light or stop sign...jeep produced a software upgrade/update and it's like a totally different machine. I truly hope GM provides a software update for the A6/A8 cars. You should have INSTANT power when you lean on the gas.

If this doesn't get resolved over the next couple months, I'll get the M7.

VNAMVET

All you have to do is drive your C7 with the T/C off........ALL the time. There will be no lag, hesitation, nothing... when you jump on the "go pedal"......no matter what mode you are in, your car will scream forward........

Vin 0287, build date 11 Sep 13.

The sky is not falling.........try it.