froggy47

A friend at autox practice today showed up with an 09 z06. He has tracked it a few times & I asked him if he had trouble with the tpms cutting power on the car or any such thing as I've read on the forum that pretty much everyone has that issue.

He said the "OK" range is 25psi to 50psi.

So I would think that on a track day, you're never going out with less than 35 ish cold and that the pressure gain is not going to put you over 50.

So what am I missing here? Did GM raise the upper limit on newer c6's?

BEZ06

Although there are some small differences from year to year in how a C6 may react to no sensors or a sensor going bad, there are no differences in any model year C6 as far as the high and low pressure alerts.

You'll get a low pressure alert when the pressure falls below 24 psi in a tire, and that will likely invoke the limp mode. I've had a tire lose pressure and I got the alert, but it was while driving on the street and I didn't drive aggressively so I never got any power reductions. I did get a "limit sped to 55" message, but I was able to drive faster than that. I believe that if you're driving with AH in Comp or off completely that it will automatically come back full on if pressure drops below 24 psi while driving, and AH will react in a very intrusive and limiting manner.

Some roadcourse guys will run with very low pressures during qualifying or TT's and that could cause AH issues, but there are workarounds for very short duration sessions.

Drag racers often run low pressure - less than 24 - and may have limp mode problems due to that, but there are workarounds.

You'll get a high pressure alert above 42 psi. I've experienced that on the track and it did absolutely nothing to the AH - it didn't pop the AH back to full on, and I could drive aggressively with no AH intervention at all.

There are a couple things that are different between the model years:
Bob

froggy47

Thanks Bob for a very thorough post. I can def. see going over 42 in a session. My pal is an engineer who loves to be very specific about the car, not sure why he said 50.

I don't see why so many track guys have an issue, then, unless they just don't like seeing the overpressure warning?

Unless I am still missing something.

harrydirty

Actually, I think there is more to it than just the 60, 30, 20 minute limits. I seem to recall on my '07Z that I could not get it into Comp mode when I did not have my sensors programmed. I can't recall exactly, but I think the only two choices were traction control off/AH on, and everything off. I also seem to recall that with everything off, the car seemed unstable when braking hard and as the day wore on, the AH seemed more intrusive, to the point where it was unexpected/unwelcome and not really fun anymore.

I would love to see someone who has demonstrated a consistent way to still get Comp Mode without tpms sensors programmed in a '07 (or newer) Z06.

X25

As Bob mentioned, there's no problem getting the warning message with higher pressures; it does not change the behavior of the AH, meaning AH does not intervene unexpectedly.

The problem is when one of the sensors fail. Some owners reported in other treads that their TPMS sensors failed prematurely due to high stress endured during track duty. When a sensor fails and stops pinging, the newer models get to the limp mode within 20 minutes, which activates the AH with very low thresholds, causing it to activate unexpectedly at the track pretty much everywhere you push the car to turn.

I have never had an issue with the TPMS sensors, and I actually love using them since it makes it easier for me to monitor my tires pressures (and indirectly the average temp of tires derived from the delta in pressure from the start). That said, if the sensors started failing like happened to some, I can see how quickly it could become irritating and scary with the unexpected AH behavior.

BEZ06

Actually, if you're out on the track in Comp or with AH completely off (or driving down the street, for that matter) and a sensor fails (or a tire loses pressure), the AH will immediately go back full on, and as you say, in a very obtrusive mode!!

The time period thingy comes into play when you are running with NO sensors (or with none of the four sensors programmed into the TPMS).

With no sensors, the time period begins every time you start the engine. During the time period, you can turn off TC, put AH in Comp mode, or turn AH off completely, and you will have no problems at all with the weird very intrusive limp mode of the AH.

If I were to run my 2006 Z06 with no sensors at a track event, I could drive out to the grid or staging area and shut down. When I restart I would have 60 minutes where I could run in Comp or with AH completely off and have no unwanted intervention from the AH - but, at the end if the 60 minutes the AH would come back full on and create limp mode issues.

If you have a model year with the 30 minute time period, you can still run most 20 or 25 minute HPDE sessions with no problem. With a 2009 or later with the 20 minute limit, you'll probably have issues toward the end of a session.

If you drive with no sensors on the street, even when the AH goes into its limp mode you won't have any problems - it's only going to give you problems when you drive aggressively.

Bottom line:
I totally agree with running sensors in my track wheels - if I start losing pressure while on the track I want to know about it!!!

Bob