Jeep Garage  - Jeep Forum

Jeep Garage - Jeep Forum (http://www.jeepgarage.org/forums.php)
-   Grand Cherokee SRT - WK2 (http://www.jeepgarage.org/f97/)
-   -   To the tech. gurus...... (http://www.jeepgarage.org/f97/to-the-tech-gurus-27332.html)

BostonDMD 08-19-2011 12:58 PM

To the tech. gurus......
 
When you left foot brake in WK1 or WK2 while maintaining constant throttle, does the computer shut off the throttle?

In other words, let's say you are at 50% throttle and you left foot brake for a sweeper turn for more than 2 seconds while still being at 50% throttle, does the throttle get shut off by the computer since it notices that the brake is also on?

I hope the computer doesn't shut off throttle response, it would make it more fun at the track, but also in snow covered roads......

If you have no idea of what I am talking about, please disregard this post......

Schleprock 08-19-2011 01:07 PM

Re: To the tech. gurus......
 
If your simple question is: Can you apply brake and throttle at the same time (i.e. brake stand/power braking), the answer is Yes

BostonDMD 08-19-2011 01:29 PM

Re: To the tech. gurus......
 
Schleprock, thanks for the info., but not exactly what I was asking.

In brake stand, you apply the brake first then the throttle......

In left foot braking you are at constant throttle first, then apply the brake.....

In my Cayenne S or Cayman S for that matter, the computer allows brake stand but not left foot braking at constant throttle.

Being able to left foot brake while at constant throttle allows better vehicle's weight transfer management (makes you smoother) on a track or on an icy/snow covered road, and that is why I am curious about the Jeep.

Sorry for the long post.....

Scottina06 08-19-2011 02:16 PM

Re: To the tech. gurus......
 
this is an excellent question for the upcoming SRT engineers chat!

BostonDMD 08-19-2011 02:33 PM

Re: To the tech. gurus......
 
Yes Scott, we can wait for the engineers......

or may be next time out on the road with your WK1, keep steady throttle with your right foot and then apply minimal pressure on the brake pedal with your left foot.....

then report back your results........:)

Yaccster 08-20-2011 10:45 AM

Re: To the tech. gurus......
 
Tried this a bit today straight line and a little turn, didn't seem to care that I had the brake and throttle going at the same time in my '06 WK1 JGC SRT/8.

soontobesrt 08-20-2011 10:51 AM

Re: To the tech. gurus......
 
Hmmm I dont see why not. I dont have definitive answer but maybe can try to help spawn an answer lol. You say your Porsche doesn't allow it? So are you saying while driving down a road, if you press the brake while on the throttle it will still brake normally and disregard the throttle inputs completely? Wont it try to override the brakes and power through them? Some sort of safety mechanism Id bet for "grannies" who hit both pedals maybe???

Ive never heard of this which is why Im skeptical and would lean towards the accelerator input being completely unaffected by the brake input but it makes sense a sensor may be put in for safety.

To my experience in the WKs when driving down the road throttle still works and will power through the breaks. But I dont suggest that of course as thats only going to cause driveline issues over time in a straight line of course. If you are tracking it, well thats another story but Id bet you can get on the brakes hard and still be on the throttle for bettering corner and quick exit speeds.

To test, we just need a WK2 owner to go drive and hit brake while on gas and see if it stops or continues to "fight" forward. Im sure the SRT8 will be identical in this regard, so should answer your question :)

BostonDMD 08-20-2011 10:56 AM

Re: To the tech. gurus......
 
In the newer Porsches it is a safety issue, can't left foot brake more than 3 sec.
In my 1987 911 obviously is a different story since there are no nannies whatsover, no ABS, nor power steering, therefore I use LFB in several fast sweepers......

Thanks for the info. guys

soontobesrt 08-20-2011 05:33 PM

Re: To the tech. gurus......
 
Quote:

Originally Posted by BostonDMD (Post 469652)
In the newer Porsches it is a safety issue, can't left foot brake more than 3 sec.
In my 1987 911 obviously is a different story since there are no nannies whatsover, no ABS, nor power steering, therefore I use LFB in several fast sweepers......

Thanks for the info. guys

Heel-toeing and double cluchin' lol, just a regular day at the cricuit :D

Harrison@Stage6 08-22-2011 02:05 PM

Re: To the tech. gurus......
 
When you apply gas and brake at the same time for more than 3 seconds, the TCM's torque managment comes in. It will first pull timing until the TM is seen that the TCM wants. Never tried it driving, but I know at the drag strip if you hold it at the line for more than 3 seconds, it will come out of the hole like a dog.

The traction control retards timing first or it will pull throttle if too much input is seen. This is all for the WK1 so I'm not sure what the WK2 will do. I can have a much much better answer for you in a month or so. Don't ask how b/c I won't tell but you'll have the exact answer as to what the PCM does. Take care....


All times are GMT -5. The time now is 09:09 AM.

Powered by vBulletin® Version 3.8.8 Beta 4
Copyright ©2000 - 2014, vBulletin Solutions, Inc.
Copyright 2012 - JeepGarage.Org
The Jeep Grand Cherokee Owners Community