ZenicaPA

I was reading some of the recent posts C7 owners made about driving in the Tr/WET mode vs Touring or Sport.

I took my C7 out today for a quick drive and put it into Track/Wet mode. I wanted to run a few things by those that have used this mode before. I notice a pronounced vibration in the Tr/Wet mode that isn't present in Sport or Touring (or Eco/Weather). It is very obvious sitting in the car but it doesn't seem so just by watching the video.

The vibration occurs almost immediately that it downshift into the lowest gear for the speed. It also seems to have a hesitation before allowing the engine RPM to climb. This hesitation exists in all speeds and all gears as I was at a stop and wanted to turn left. Based on the distance of oncoming traffic I knew I had enough time if I applied the right about of acceleration but the throttle lagged/delayed for a good solid second before the car even started to move. During this time there wasn't even an increase of RPM.

Frankly I think the car was more responsive in Sport mode than the Track mode. Perhaps I didn't engage the Track/Wet mode properly. I turned the dial and then pressed the button until Wet was illuminated. The display showed WET for a brief time before returning to the coolant temp.

There are those here that will probably see this and know right away what I did wrong so please...tell me so I can fix it and test again!

First up is Sport, then Track






EDIT:
Added links, not sure why embedded videos won't play.

Foosh

Zen, I have no clue.

Sounds like you have an A8. Mine is an M7. I've never noticed anything like what you describe. I hope it's not related to the dreaded A8 syndrome.

I can see that you're in PTM mode because your traction and stability control lights are on, even though those systems are still active in PTM Wet & Dry.

ZenicaPA

I've driven today with the Tr/WET settings and it definitely behaves strangely.
There is a noticeable throttle lag, the exhaust sounds like a truck using a Jake brake.
It isn't a setting I think I'd want to use but I also don't think its working correctly.
My concern is the dealer may rebuke the claim saying Track mode isn't meant for the street or some other blah blah blah excuse.

Patches

That sounds wrong. I have an M7 Z51 '14 and was playing around with the different modes on the way home form work yesterday - specifically to try the Track-Wet mode I've also been reading about here. My car drove perfectly while I was in Track-Wet and, in fact, seemed smoother than Tour mode. The road I commute on is a combination of 12 miles of ratty, multi-lane highway, surface streets through San Juan Capistrano and then ~20 miles of good and mediocre-condition 2-lane canyon road (Ortega Hwy.) coming out at Lake Elsinore where I live. The car felt smoother with better dynamics than in Tour mode which is what I usually drive in due to the condition of the roads here.

If your dealer gives you grief about engaging Track mode when you're not actually on a race track, seek a more accommodating Service Dept. My Service Rep in Temecula wouldn't bat an eye at this - he would just pull the car into service to investigate.

jcp911s

Was it actually wet when you engaged it?

Patches

It was 100% bone-dry when I did - doesn't need to wet to work. It was a little disconcerting at first as I've read you can bend a wheel rim if you hit a pothole in Track mode due to the stiffening of the mag ride dampers. The ride was actually a bit more compliant but with the control feeling a bit more positive. Subtle but noticeable. I have been driving this route to work every day of the week for the past 6+ years so I know its topography and how it feels very well.

NSC5

Zenica,
By choosing track wet you are telling the control systems that the tire traction is reduced so it is going to behave differently by preemptively taking measures to avoid loss of control. For example the "Jake brake" sound you hear is likely during harder acceleration when the ECM is pulling timing to reduce power. PTM allows you to request full throttle out of a turn with the engine power limited by the control system to maintain control. I really don't think track/wet is a good choice for street driving.

And if you haven't already read through it look at the Ask Tadge thread about PTM modes: https://www.corvetteforum.com/forums...post1590304017 As noted in his answer the TCS slip target is lower in Track Wet than in a normal driver mode.

Foosh

I've found that using Track/PTM Wet on the street is a good setting in that you can be in MSRC Tour mode on rough pavement, which is common in my area, and not slip at all on the street when driving semi-aggressively. You still have full power up until the point that the tires lose grip. You'll obviously slip less on dry than wet pavement. In PTM Wet, in dry conditions, I've confirmed that at the very earliest stages of wheel spin, it does intervene quicker, but it does allow the loss of grip to begin. I think the eDiff setting in PTM Wet also improves stability and handling.

In normal Tour mode, it's fairly routine to get some slippage with heavy throttle, and Stabilitrak doesn't intervene quite as quickly. Sometimes that's fun, but I have found Track/PTM Wet quite impressive and enjoyable on the street.

ZenicaPA

I believe you are correct, the sound is under WOT and is accompanied by a marked decrease in acceleration.

Why would anyone find this desirable in dry conditions?

NSC5

The electronic controls are better than most drivers at managing acceleration out of a turn which I think is PTM's forte. The driver can go full throttle and PTM will provide the level of torque necessary to hit what is calculated to be the optimal amount of tire slip which is further fine tuned by actual traction conditions. But when the mode is set to wet the PTM is accepting the driver's opinion that the road condition is wet/low traction so it is going to reduce power far more than is really necessary.

Foosh

It may be a decrease in WOT, but it's not a decrease in acceleration. If you're spinning tires, you're not accelerating as fast as you could be.

The average person thinks that if traction control and stabilitrak cut power they are somehow going slower. That is not necessarily the case. I think people are fooled by WOT sounds, and tires breaking loose into thinking they are going faster. Usually, they're not.

The system is doing an excellent job of keeping the tires hooked up, which means faster acceleration in the vast majority of cases.

I don't think that's necessarily the case. As I said above while in PTM/Wet in dry conditions, I can repeatedly cause the tires to begin to break lose before power is cut, but the intervention happens much more quickly than in the other modes. Running PTM/Wet in dry conditions will cause much less intervention than running PTM/Wet in wet conditions.

ZenicaPA

I said loss of acceleration because the g forces I could feel and the thrust planting my head into the headrest both eased up when I could hear the exhaust indicating the timing was retarded.

This meant a loss of acceleration and this was without wheel slip or loss of physical tire traction.

The timing retardation seems to happen very early on after WOT and continues as the RPM climbs 3k RPM --- all the while my Continentals never lose grip.

Foosh

OK, whatever. I have arrived at an entirely different conclusion.