Possible Launch Control issue in M7
Thread Starter
Racer
Joined: Apr 2014
Posts: 380
Likes: 10
Possible Launch Control issue in M7
Upon attempting launch control in my 2014 M7 Z51, I could have sworn I recall the rpms getting up to 4500 or so the first time I ever tried it out just before I dumped the clutch.
After watching several launch control feature demos by GM, I have even heard them say the car leaves at 5,000 rpm. Yes, I know how to properly turn the feature on, but now the rpms bump up to around 4000 and then quickly settle to around 3700-3800 rpm.
What rpms are other with M7s seeing there rpms settle down to just before dumping the clutch when using launch control? Again, my car now revs in launch control to around 4,000 rpm, and then quickly settles down to around 3700-3800 just before I dumped the clutch. My car also seems to leave somewhat softer than the first time I remember using the launch control feature. Any thoughts?
After watching several launch control feature demos by GM, I have even heard them say the car leaves at 5,000 rpm. Yes, I know how to properly turn the feature on, but now the rpms bump up to around 4000 and then quickly settle to around 3700-3800 rpm.
What rpms are other with M7s seeing there rpms settle down to just before dumping the clutch when using launch control? Again, my car now revs in launch control to around 4,000 rpm, and then quickly settles down to around 3700-3800 just before I dumped the clutch. My car also seems to leave somewhat softer than the first time I remember using the launch control feature. Any thoughts?
Melting Slicks
Joined: Oct 2009
Posts: 2,004
Likes: 392
From: Long Island New York
Sounds like it's working perfect. As far as the car leaving harder or softer then in the past that could be a lot of things. Some examples would be if you launch on asphalt vs cement, if the ambient temperature is hotter or cooler, if your tires are cold vs warm..
If it launched from 5k it would just spin unless you were on a prepped surface.
If it launched from 5k it would just spin unless you were on a prepped surface.
Last edited by BlueDevilZ51; Aug 19, 2015 at 06:55 AM.
Thread Starter
Racer
Joined: Apr 2014
Posts: 380
Likes: 10
I hope you are right with it working correctly. Still seems strange for it to launch at 4500 one day and now it launches at around 3700 rpm. I think the degree on how hard it leaves can have something with the pavement surface, temp etc; however, I would have thought it would rev up and settle at the same rpm each time before I actually dump the clutch.
Safety Car
Joined: Mar 2014
Posts: 4,483
Likes: 668
From: Kilmarnock Va
Drifting
Joined: Aug 2002
Posts: 1,452
Likes: 190
From: Zion NC
I hope you are right with it working correctly. Still seems strange for it to launch at 4500 one day and now it launches at around 3700 rpm. I think the degree on how hard it leaves can have something with the pavement surface, temp etc; however, I would have thought it would rev up and settle at the same rpm each time before I actually dump the clutch.
It's working correctly. It adjusts it for current conditions and learns from prior launches I believe.
Drifting
Joined: Sep 2014
Posts: 1,267
Likes: 119
From: Bellevue WA
Sounds like it's working perfect. As far as the car leaving harder or softer then in the past that could be a lot of things. Some examples would be if you launch on asphalt vs cement, if the ambient temperature is hotter or cooler, if your tires are cold vs warm..
If it launched from 5k it would just spin unless you were on a prepped surface.
If it launched from 5k it would just spin unless you were on a prepped surface.
Melting Slicks
Joined: May 2012
Posts: 2,904
Likes: 315
From: Cedar Falls Iowa
Another ditto on sounds like it's working.
With the factory tires in almost any conditions, 5k is crazy high to dump from unless you're gonna do a smoke show. The few times I've tried to launch mine, the sweet spot seemed to be a 2500ish.
With the factory tires in almost any conditions, 5k is crazy high to dump from unless you're gonna do a smoke show. The few times I've tried to launch mine, the sweet spot seemed to be a 2500ish.
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Drifting
Joined: Dec 2015
Posts: 1,410
Likes: 414
From: Germantown Maryland
I haven't tested this theory yet but wonder if the initial RPM might depend depend on the PTM sub-mode? For instance you would think it would be lower for wet vs dry. My only attempt (that worked fine) was in dry and RPM was somewhere near 4500-4700 but I didn't make a note of it.
Last edited by raylo; Mar 1, 2016 at 03:58 PM.