Has anyone else had this happen?
04-01-2009, 03:31 PM
#1
Racer
Thread Starter
Has anyone else had this happen?
I'm not sure if it's a AWD specific issue or not. It's happened about four times while taking a right turn going 5-10 mph. When I gently press the gas it feels like the VSC kicks in, totally delaying power for just a split second, and then it's back to normal. So far it's happened at different locations every time and i've tried to replicate it at two of the same spots, but nothing. These roads were not really bumpy but not perfectly smooth either. I've been experimenting with the VDC off around the city to see if it does it with it off, and it hasn't.
The RDX doesn't do it at these spots or anytime for that matter, so I'm guessing it's a really sensitive VDC on the TL. Maybe with the 19" HPT's the stiffer ride is setting off the VDC. Has anyone else experienced this?
The RDX doesn't do it at these spots or anytime for that matter, so I'm guessing it's a really sensitive VDC on the TL. Maybe with the 19" HPT's the stiffer ride is setting off the VDC. Has anyone else experienced this?
04-01-2009, 05:41 PM
#3
I wonder if the transmission is shifting from 3rd to 1st?
04-01-2009, 06:33 PM
#4
Racer
Thread Starter
Maybe but one time I was barely moving, and rolling on from a dead stop so it was def in 1st. It feels exactly like someone just kills the juice for a split second, so I assume it's the VDC. If it is, it's way too sensitive!
04-01-2009, 06:43 PM
#5
Suzuka Master
I'm not sure if it's a AWD specific issue or not. It's happened about four times while taking a right turn going 5-10 mph. When I gently press the gas it feels like the VSC kicks in, totally delaying power for just a split second, and then it's back to normal. So far it's happened at different locations every time and i've tried to replicate it at two of the same spots, but nothing. These roads were not really bumpy but not perfectly smooth either. I've been experimenting with the VDC off around the city to see if it does it with it off, and it hasn't.
The RDX doesn't do it at these spots or anytime for that matter, so I'm guessing it's a really sensitive VDC on the TL. Maybe with the 19" HPT's the stiffer ride is setting off the VDC. Has anyone else experienced this?
The RDX doesn't do it at these spots or anytime for that matter, so I'm guessing it's a really sensitive VDC on the TL. Maybe with the 19" HPT's the stiffer ride is setting off the VDC. Has anyone else experienced this?
04-01-2009, 08:09 PM
#6
Racer
Thread Starter
Are you sure it is the VSC? I have had something happen a few times when slowing down and then trying to accelerate under the right circumstance the ECU seems to get confused and the car actually hesitates then ramps back up like a minor jerky action. Haappend maybe 4-5 times in first 2K miles.
04-01-2009, 08:36 PM
#7
I'll watch for it. Can't say that I have noticed it
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04-01-2009, 10:44 PM
#9
Could be sensitivity in the gradelogic. You hit the gas just enough to cause downshift then let off, causing confusion in which gear it supposed to be or the opposite, it's downshifting while you slow down, at the same time you hit the gas. Common on all Gradelogic transmissions. If it's vsa, you should see the symbol, and that would mean a) it's behaving like the FWD versions do, cutting throttle just before the SH transfers power to the rear or b) it's the transfer itself causing the delay.
04-02-2009, 10:02 AM
#10
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Could be sensitivity in the gradelogic. You hit the gas just enough to cause downshift then let off, causing confusion in which gear it supposed to be or the opposite, it's downshifting while you slow down, at the same time you hit the gas. Common on all Gradelogic transmissions. If it's vsa, you should see the symbol, and that would mean a) it's behaving like the FWD versions do, cutting throttle just before the SH transfers power to the rear or b) it's the transfer itself causing the delay.
04-02-2009, 10:09 AM
#11
Senior Moderator
put the car in S mode and make sure you start out in 1st gear, try replicating. Then try 2nd. If it doesn't happen, then put it in D and try again.
04-02-2009, 12:05 PM
#13
Racer
Thread Starter
04-02-2009, 01:25 PM
#14
I was looking for the actual file that described this, but from memory, this is partially correct. The original SH-AWD system (RDX, MDX, Pre-MMC RL) the Left - Right torque transfer only happened in second gear and up. The new system works in first for the new TL and 2009 RL.
04-02-2009, 01:32 PM
#15
Found it!
Of course the TL only accelerates the outside rear wheel by 1.7%
The previous RL's SH-AWD™ system didn't initiate rear side-to-side torque distribution until Second gear. However, on the 2009 RL new control parameters allow rearward torque delivery in First gear. Plus, front-to-rear and side-to-side power transfer happens much quicker with improved precision. The benefit of the revised SH-AWD™ system is improved accuracy, quicker response, and more power able to be applied to a specific rear wheel.
Torque splits are as follows:
During straight-line cruising and moderate cornering below half throttle, up to 70-percent of engine torque is delivered to the front wheels.
In full-throttle straight line acceleration, up to 40-percent of the power is sent to the rear axle.
In hard cornering, up to 70-percent of available torque goes to the rear wheels for enhanced chassis balance. Up to 100-percent of this torque can be applied to the outside rear wheel that can also be overdriven up to 5.7-percent by a built-in acceleration device.
Torque splits are as follows:
During straight-line cruising and moderate cornering below half throttle, up to 70-percent of engine torque is delivered to the front wheels.
In full-throttle straight line acceleration, up to 40-percent of the power is sent to the rear axle.
In hard cornering, up to 70-percent of available torque goes to the rear wheels for enhanced chassis balance. Up to 100-percent of this torque can be applied to the outside rear wheel that can also be overdriven up to 5.7-percent by a built-in acceleration device.
04-02-2009, 02:48 PM
#16
If anyone can confirm it's not vsa, and the car does downshift into first, then I would think it is a mechanical design. The extra load strain in the lower gear worried Acura, probably why they never put in it the earlier models.
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