Active handling too sensitive on 2008 Widebody?
11-27-2015, 01:11 PM
#1
Burning Brakes
Thread Starter
Active handling too sensitive on 2008 Widebody?
I had a 2005 C6 Z51 that I could take right hand corners, gas it, and it just went with no drama. Now I have a 2008 C6 Z51 that the engine cuts out and ACTIVE HANDLING light comes on with just moderate gas in a right hand turn. So the question is, has the active handling mode in the ECU changed between the years (05 vs 08)?
I have a widebody kit on the rear and use factory grandsport rims and tire sizes, could that be part of the problem for the ECU?
I would think the wider tires would grip better, negating the active handling cutting in so soon. I find this can be dangerous if you want to accelerate fast after realizing a car is approaching fast after you just made a right hand turn.
Thoughts? Solutions?
I have a widebody kit on the rear and use factory grandsport rims and tire sizes, could that be part of the problem for the ECU?
I would think the wider tires would grip better, negating the active handling cutting in so soon. I find this can be dangerous if you want to accelerate fast after realizing a car is approaching fast after you just made a right hand turn.
Thoughts? Solutions?
11-27-2015, 01:28 PM
#2
Active handling will use a couple of sensors for the intial input, with the most important ones being the steering wheel sensor, the Yaw/accelerator sensor, and the wheel speed sensors.
Lets start with the wheel speed sensors, and the ECM is looking for the rear tires to be 1.04" larger OD that the front tires. So if you have changed tire sizes that has changed the percentage that the front tires rotate against there rear tires, this this cause problems with the ECM not seeing the tires covering the same amount of ground correctly, and faster to kick in the AH with even the slightest of rear tire slip (ecm seeing light tire slip as major tire slip/spin instead.
Next we come to the Yaw/accelerator sensor (it mount below the radio) in combination with the steering wheel sensor, and depending on it's sensitivity, may kick in the AH when the back end starts stepping out faster as well.
Lastly, we come to the ECM setting.
So in standard mode, when the back end starts to slip out, the AH should be kicking in. If you push the TC button twice, this will put the car into comp mode, which turns traction control off, and desensitize AH to a less degree (will allow the back end to step out slightly farther before AH kicks in instead). Now if you hold the TC button down for 5 seconds, this will turn both T/C and AH off, leaving only ABS active only(no way to turn ABS via the TC button).
So again, check to make sure that the back tires are 1.04" larger OD than that front tires to begin with so it not a tire speed issue with the ECM, and that once the back end does start to slide out, then the yaw sensor will kick the AH in (read could be the difference of the two models on the amount of tire traction to allow the back tires to stick and hold during the hard push out of the corner). And to point out, summer performance tires loose there grip rapidly with the age of the tires, since the older the tires, the harder the rubber becomes.
Also to point out since a lot of guys love to just slam/lower the vets. When you lower the vet, you still need to corner balance the car. If the car was lowered and you want to at least give it a quick check on how close the car is still to OEM balancing, then measure from the fender lips to the ground on level ground. The rear fender lips to the ground should be 1.3" higher off the ground that the front fender lips to the ground on a narrow body car.
Lets start with the wheel speed sensors, and the ECM is looking for the rear tires to be 1.04" larger OD that the front tires. So if you have changed tire sizes that has changed the percentage that the front tires rotate against there rear tires, this this cause problems with the ECM not seeing the tires covering the same amount of ground correctly, and faster to kick in the AH with even the slightest of rear tire slip (ecm seeing light tire slip as major tire slip/spin instead.
Next we come to the Yaw/accelerator sensor (it mount below the radio) in combination with the steering wheel sensor, and depending on it's sensitivity, may kick in the AH when the back end starts stepping out faster as well.
Lastly, we come to the ECM setting.
So in standard mode, when the back end starts to slip out, the AH should be kicking in. If you push the TC button twice, this will put the car into comp mode, which turns traction control off, and desensitize AH to a less degree (will allow the back end to step out slightly farther before AH kicks in instead). Now if you hold the TC button down for 5 seconds, this will turn both T/C and AH off, leaving only ABS active only(no way to turn ABS via the TC button).
So again, check to make sure that the back tires are 1.04" larger OD than that front tires to begin with so it not a tire speed issue with the ECM, and that once the back end does start to slide out, then the yaw sensor will kick the AH in (read could be the difference of the two models on the amount of tire traction to allow the back tires to stick and hold during the hard push out of the corner). And to point out, summer performance tires loose there grip rapidly with the age of the tires, since the older the tires, the harder the rubber becomes.
Also to point out since a lot of guys love to just slam/lower the vets. When you lower the vet, you still need to corner balance the car. If the car was lowered and you want to at least give it a quick check on how close the car is still to OEM balancing, then measure from the fender lips to the ground on level ground. The rear fender lips to the ground should be 1.3" higher off the ground that the front fender lips to the ground on a narrow body car.
Last edited by Dano523; 11-27-2015 at 01:33 PM.
11-27-2015, 01:38 PM
#3
Burning Brakes
Thread Starter
I have the stock grandsport sizes (tires and rims), so if it works on a real grandsport, it should work on mine me thinks, UNLESS there is a different ECU setting for the grandsport that I need to make?
11-27-2015, 02:16 PM
#4
Problem is you did not tweak the suspension set up when you went to the wide body/GS sport size tires.
The GS runs rims with different off set to push the tires more outwards, and with the wider rims, you have more rear end grip as well.
So with the narrow body Z-51 set up with normally 285 size tires, the rear end is set up to let the rear end come loose faster to balance the car to the front end.
Now with the 275F/325R wide body, the back end suspension is letting the rear end break out to soon instead.
Bluntly, at this point without writing a novel, would just change the sway bars out to Z06's, the trans spring out to Z06's and the shocks to DRM units. You could go the way of going to the slightly softer GS set up instead, but a better chance of finding the used Z06 parts from someone on the inexpensive side that went to a tighter set on their Z06 instead.
As for your ride height from the fenders on the wide body car for a OEM'ish type set up balance, back fender lips should be .9" higher than the fronts off the level ground instead.
11-27-2015, 07:44 PM
#6
Le Mans Master
Just turn off the TC/ AH, problem solved!
11-27-2015, 11:06 PM
#7
Burning Brakes
Thread Starter
Problem is you did not tweak the suspension set up when you went to the wide body/GS sport size tires.
The GS runs rims with different off set to push the tires more outwards, and with the wider rims, you have more rear end grip as well.
So with the narrow body Z-51 set up with normally 285 size tires, the rear end is set up to let the rear end come loose faster to balance the car to the front end.
Now with the 275F/325R wide body, the back end suspension is letting the rear end break out to soon instead.
Bluntly, at this point without writing a novel, would just change the sway bars out to Z06's, the trans spring out to Z06's and the shocks to DRM units. You could go the way of going to the slightly softer GS set up instead, but a better chance of finding the used Z06 parts from someone on the inexpensive side that went to a tighter set on their Z06 instead.
As for your ride height from the fenders on the wide body car for a OEM'ish type set up balance, back fender lips should be .9" higher than the fronts off the level ground instead.
The GS runs rims with different off set to push the tires more outwards, and with the wider rims, you have more rear end grip as well.
So with the narrow body Z-51 set up with normally 285 size tires, the rear end is set up to let the rear end come loose faster to balance the car to the front end.
Now with the 275F/325R wide body, the back end suspension is letting the rear end break out to soon instead.
Bluntly, at this point without writing a novel, would just change the sway bars out to Z06's, the trans spring out to Z06's and the shocks to DRM units. You could go the way of going to the slightly softer GS set up instead, but a better chance of finding the used Z06 parts from someone on the inexpensive side that went to a tighter set on their Z06 instead.
As for your ride height from the fenders on the wide body car for a OEM'ish type set up balance, back fender lips should be .9" higher than the fronts off the level ground instead.
Last edited by ULEWZ; 11-27-2015 at 11:06 PM.
11-28-2015, 04:17 PM
#10
Tech Contributor
You say you have factory Grand Sport rims and tires, but only the wide rear fenders?
Double check your front tire size. The 275 GS front tires won't fit on regular narrow fenders, they rub.
If you have 325 tires in the rear and 245 stock regular body fronts, that could be causing your problem. The car is looking for a certain ratio front to rear tire size stagger and you don't have it with 245/325. You'll probably get the "engine drag control" message with this setup.
If I misunderstood and you have wide fenders front and rear and 275/325 tires, then I would suggest your 2008 has more power than your 2005 and perhaps you are just overpowering the tires around the same turn. Particularly if you have older tires on the 2008 vs the 2005.
Let us know on the tire sizes.
Double check your front tire size. The 275 GS front tires won't fit on regular narrow fenders, they rub.
If you have 325 tires in the rear and 245 stock regular body fronts, that could be causing your problem. The car is looking for a certain ratio front to rear tire size stagger and you don't have it with 245/325. You'll probably get the "engine drag control" message with this setup.
If I misunderstood and you have wide fenders front and rear and 275/325 tires, then I would suggest your 2008 has more power than your 2005 and perhaps you are just overpowering the tires around the same turn. Particularly if you have older tires on the 2008 vs the 2005.
Let us know on the tire sizes.
11-29-2015, 12:09 PM
#11
Burning Brakes
Thread Starter
You say you have factory Grand Sport rims and tires, but only the wide rear fenders?
Double check your front tire size. The 275 GS front tires won't fit on regular narrow fenders, they rub.
If you have 325 tires in the rear and 245 stock regular body fronts, that could be causing your problem. The car is looking for a certain ratio front to rear tire size stagger and you don't have it with 245/325. You'll probably get the "engine drag control" message with this setup.
If I misunderstood and you have wide fenders front and rear and 275/325 tires, then I would suggest your 2008 has more power than your 2005 and perhaps you are just overpowering the tires around the same turn. Particularly if you have older tires on the 2008 vs the 2005.
Let us know on the tire sizes.
Double check your front tire size. The 275 GS front tires won't fit on regular narrow fenders, they rub.
If you have 325 tires in the rear and 245 stock regular body fronts, that could be causing your problem. The car is looking for a certain ratio front to rear tire size stagger and you don't have it with 245/325. You'll probably get the "engine drag control" message with this setup.
If I misunderstood and you have wide fenders front and rear and 275/325 tires, then I would suggest your 2008 has more power than your 2005 and perhaps you are just overpowering the tires around the same turn. Particularly if you have older tires on the 2008 vs the 2005.
Let us know on the tire sizes.
11-29-2015, 01:04 PM
#13
Burning Brakes
Thread Starter
Stock Grand Sport rims (factory, not after market)
front: 18 inch x 9.5 inch, +40 offset
rear: 19 inch x 12 inch, +59 offset
275/35 ZR18
325/30 ZR19
Note, these rims/tires do not rub on my car, stock front end, widebody rear. I can send fender pictures if this is not believable.
From what I read, the new combo is -.4% difference front and rear.
front: 18 inch x 9.5 inch, +40 offset
rear: 19 inch x 12 inch, +59 offset
275/35 ZR18
325/30 ZR19
Note, these rims/tires do not rub on my car, stock front end, widebody rear. I can send fender pictures if this is not believable.
From what I read, the new combo is -.4% difference front and rear.
11-29-2015, 01:12 PM
#14
Tech Contributor
ULewz I'm shocked that these don't stick out a half inch in front, but that's great for you that they don't!
I've seen dozens of pics like this in the last 10 years.
[/QUOTE]
Given that you've got proper sized rubber on your car, I'll go back to my original thought that the extra power of your ls3 vs ls2 is causing your active handling to kick in. FYI, a LS3 stock is about 380/380 to the wheel and that's what you have with headers on a LS2. A LS2 is about 340/340 stock.
The brand and condition of your tires, primarily age, plays a big part as well.
To your question, was active handling set to me more "strict" for 08 vs 05? I can't say with authority. I do know that 08 has a much faster computer and that it's much more sensitive to things like tire pressure sensors than 05..... so my uneducated guess is yes, it's refined and enhanced in the 08 vs 05. I'm pretty sure about that matter of fact. Whether it's more sensitive? That I can't say.
I've seen dozens of pics like this in the last 10 years.
[/QUOTE]Given that you've got proper sized rubber on your car, I'll go back to my original thought that the extra power of your ls3 vs ls2 is causing your active handling to kick in. FYI, a LS3 stock is about 380/380 to the wheel and that's what you have with headers on a LS2. A LS2 is about 340/340 stock.
The brand and condition of your tires, primarily age, plays a big part as well.
To your question, was active handling set to me more "strict" for 08 vs 05? I can't say with authority. I do know that 08 has a much faster computer and that it's much more sensitive to things like tire pressure sensors than 05..... so my uneducated guess is yes, it's refined and enhanced in the 08 vs 05. I'm pretty sure about that matter of fact. Whether it's more sensitive? That I can't say.
11-29-2015, 01:26 PM
#15
Race Director
Member Since: Sep 2007
Location: Peoria/Phoenix AZ
Posts: 16,555
Received 2,061 Likes
on
1,505 Posts
C6 of Year Finalist (performance mods) 2019
Does it also get tail happy on a equally sharp left-hand turn?
I'm trying to see if driver and fuel load are contributing factors.
I'm trying to see if driver and fuel load are contributing factors.
11-29-2015, 01:37 PM
#16
Burning Brakes
Thread Starter
I never said the front tires don't stick out slightly, I just said they do not rub. I added small front fender splash guards and that makes it look pretty good me thinks.
I am much tighter in a right hand turn vs left, so that is why it is a problem for me.
Scenario:
Stopped at a signal light. Turn right with more than normal gas to accelerate fast to get up to speed due to fastly approaching cars.
Active handling kicks in (DIC shows the message, ACTIVE HANDLING) and cuts the power making the fast acceleration fruit less. Very minor wheel slip when it kicks in vs my old 05. New tires are being ordered soon, so time will tell.
Interestingly enough, I can spin the rear wheels while in a straight line with no DIC message, but not even slightly in a turn.
I am much tighter in a right hand turn vs left, so that is why it is a problem for me.
Scenario:
Stopped at a signal light. Turn right with more than normal gas to accelerate fast to get up to speed due to fastly approaching cars.
Active handling kicks in (DIC shows the message, ACTIVE HANDLING) and cuts the power making the fast acceleration fruit less. Very minor wheel slip when it kicks in vs my old 05. New tires are being ordered soon, so time will tell.
Interestingly enough, I can spin the rear wheels while in a straight line with no DIC message, but not even slightly in a turn.
Last edited by ULEWZ; 11-29-2015 at 01:46 PM.
11-29-2015, 07:05 PM
#17
TC will allow minor amounts of wheel spin when moving straight forward without the TC kicking in.
In a turn, rear wheel spin and the back end stepping out slightly will kick in AH isntead with all the nanies full on. As for AH kicking in more one way that the other in a turn wit the slight wheel spin only (back end not stepping out), may want to make sure that your steering wheel sensor it correctly indexed/don't have problems with the yaw sensor.
In a turn, rear wheel spin and the back end stepping out slightly will kick in AH isntead with all the nanies full on. As for AH kicking in more one way that the other in a turn wit the slight wheel spin only (back end not stepping out), may want to make sure that your steering wheel sensor it correctly indexed/don't have problems with the yaw sensor.
11-29-2015, 07:24 PM
#18
Le Mans Master
I never said the front tires don't stick out slightly, I just said they do not rub. I added small front fender splash guards and that makes it look pretty good me thinks.
I am much tighter in a right hand turn vs left, so that is why it is a problem for me.
Scenario:
Stopped at a signal light. Turn right with more than normal gas to accelerate fast to get up to speed due to fastly approaching cars.
Active handling kicks in (DIC shows the message, ACTIVE HANDLING) and cuts the power making the fast acceleration fruit less. Very minor wheel slip when it kicks in vs my old 05. New tires are being ordered soon, so time will tell.
Interestingly enough, I can spin the rear wheels while in a straight line with no DIC message, but not even slightly in a turn.
I am much tighter in a right hand turn vs left, so that is why it is a problem for me.
Scenario:
Stopped at a signal light. Turn right with more than normal gas to accelerate fast to get up to speed due to fastly approaching cars.
Active handling kicks in (DIC shows the message, ACTIVE HANDLING) and cuts the power making the fast acceleration fruit less. Very minor wheel slip when it kicks in vs my old 05. New tires are being ordered soon, so time will tell.
Interestingly enough, I can spin the rear wheels while in a straight line with no DIC message, but not even slightly in a turn.
Last edited by C U IN REARVEIW; 11-29-2015 at 07:26 PM.
11-30-2015, 11:02 AM
#19
Le Mans Master
I don't know the offset and what not as I bought the car this way but I have 285 wide tires on 10" front wheels on my base car and they tuck in nicely and don't rub.
11-30-2015, 01:22 PM
#20
Race Director
Member Since: Sep 2007
Location: Peoria/Phoenix AZ
Posts: 16,555
Received 2,061 Likes
on
1,505 Posts
C6 of Year Finalist (performance mods) 2019
I never said the front tires don't stick out slightly, I just said they do not rub. I added small front fender splash guards and that makes it look pretty good me thinks.
I am much tighter in a right hand turn vs left, so that is why it is a problem for me.
Scenario:
Stopped at a signal light. Turn right with more than normal gas to accelerate fast to get up to speed due to fastly approaching cars.
Active handling kicks in (DIC shows the message, ACTIVE HANDLING) and cuts the power making the fast acceleration fruit less. Very minor wheel slip when it kicks in vs my old 05. New tires are being ordered soon, so time will tell.
Interestingly enough, I can spin the rear wheels while in a straight line with no DIC message, but not even slightly in a turn.
I am much tighter in a right hand turn vs left, so that is why it is a problem for me.
Scenario:
Stopped at a signal light. Turn right with more than normal gas to accelerate fast to get up to speed due to fastly approaching cars.
Active handling kicks in (DIC shows the message, ACTIVE HANDLING) and cuts the power making the fast acceleration fruit less. Very minor wheel slip when it kicks in vs my old 05. New tires are being ordered soon, so time will tell.
Interestingly enough, I can spin the rear wheels while in a straight line with no DIC message, but not even slightly in a turn.
A half tank of gas and no passenger on a right turn unloads the right rear, but doesn't on a left turn. Just make sure where you do it has plenty of space in the event the backend wants to trade places with the front.