Engine Drag Control Active????
Thread Starter
Safety Car
Joined: Dec 2004
Posts: 4,477
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From: Boca Raton, FL
St. Jude Donor '05-'06-'07-'08-'09-'10-'11-'12-'13-'14
Engine Drag Control Active????
Lately my DIC has been flashing the "Engine Drag Control Active " notice. It started right after I put Z06 rear fenders and bigger rear tires on. Has anyone had this happen?
Instructor
Joined: Oct 2006
Posts: 176
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I upped my tires to 275 front and 305 back. When I have these tires on, traction control engages whenever I give it full throttle and reduces my HP. I also don't have Tire pressure sensors on these tires. Not sure if it is tire size or the lack of tire pressure sensors causing this problem. I just end up turning it off and all my power comes back.
Race Director
Joined: Mar 2005
Posts: 10,399
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From: Austin Texas
If your car is doing it on other than a downshift you have either ECM problems or badly mismatched tire sizes front to rear and have the ECM confused.
If any of the experts knows how "drag control" is done please chime in. I'm curious as to what is controlled and how. If some one downshifts from 5th to first at 75MPH what can the ECM do to keep from mechanically over revving the motor?
Edit; I just went thru my service manual, see my post @ 7:31PM.
If any of the experts knows how "drag control" is done please chime in. I'm curious as to what is controlled and how. If some one downshifts from 5th to first at 75MPH what can the ECM do to keep from mechanically over revving the motor?
Edit; I just went thru my service manual, see my post @ 7:31PM.
Last edited by haljensen; May 31, 2007 at 08:46 PM. Reason: Remove first sentence
Melting Slicks
Joined: Jun 2006
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Think of it as traction control backwards. It's designed to help keep the rear wheels from locking up on a downshift (mechanical over rev). If your car is doing it on other than a downshift you have either ECM problems or badly mismatched tire sizes front to rear and have the ECM confused.
If any of the experts knows how "drag control" is done please chime in. I'm curious as to what is controlled and how. If some one downshifts from 5th to first at 75MPH what can the ECM do to keep from mechanically over revving the motor?
If any of the experts knows how "drag control" is done please chime in. I'm curious as to what is controlled and how. If some one downshifts from 5th to first at 75MPH what can the ECM do to keep from mechanically over revving the motor?
That's the first time I ever heard of that one! Is is in the manual, or did Chevy add it as a surprise???
Race Director
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From: Austin Texas
Thread Starter
Safety Car
Joined: Dec 2004
Posts: 4,477
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From: Boca Raton, FL
St. Jude Donor '05-'06-'07-'08-'09-'10-'11-'12-'13-'14
My car is a manual Z51. I've added a supercharger, heads, cam, headers and exhaust. The tire sizes are 245/40/18 in the front and 345/30/19 in the rear.
The DIC notice comes on when the engine is revving down. I'm not always downshifting when the notice appears.
Thanks for the comments,
Jeff
The DIC notice comes on when the engine is revving down. I'm not always downshifting when the notice appears.
Thanks for the comments,
Jeff
Race Director
Joined: Mar 2005
Posts: 10,399
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From: Austin Texas
Here it is from my '05 Service manual.
"QUOTE"
Engine Drag Control (EDC)
When the driver releases the throttle, and the drag from the engine overcomes the frictional force between the tire and the road, the EDC becomes active.
The EBCM sends a torque request signal to the PCM, which stabalizes the torque at the wheels by reducing the slip at the driven wheels.
When EDC is active, the driven wheels are controlled to a target below the non-driven wheels.
Pg 5-205 under antilock brake system.
Nothing to protect from a downshift over rev. Either the tires break loose or you get a massive over rev from the rear wheels driving the engine.
"QUOTE"
Engine Drag Control (EDC)
When the driver releases the throttle, and the drag from the engine overcomes the frictional force between the tire and the road, the EDC becomes active.
The EBCM sends a torque request signal to the PCM, which stabalizes the torque at the wheels by reducing the slip at the driven wheels.
When EDC is active, the driven wheels are controlled to a target below the non-driven wheels.
Pg 5-205 under antilock brake system.
Nothing to protect from a downshift over rev. Either the tires break loose or you get a massive over rev from the rear wheels driving the engine.
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Race Director
Joined: Mar 2005
Posts: 10,399
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From: Austin Texas
My car is a manual Z51. I've added a supercharger, heads, cam, headers and exhaust. The tire sizes are 245/40/18 in the front and 345/30/19 in the rear.
The DIC notice comes on when the engine is revving down. I'm not always downshifting when the notice appears.
Thanks for the comments,
Jeff
The DIC notice comes on when the engine is revving down. I'm not always downshifting when the notice appears.
Thanks for the comments,
Jeff
Le Mans Master
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Posts: 5,707
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From: Los Angeles
Tech Contributor
Joined: Jul 2002
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From: St. Louis, MO
St. Jude Donor '08
My car is a manual Z51. I've added a supercharger, heads, cam, headers and exhaust. The tire sizes are 245/40/18 in the front and 345/30/19 in the rear.
The DIC notice comes on when the engine is revving down. I'm not always downshifting when the notice appears.
Thanks for the comments,
Jeff
The DIC notice comes on when the engine is revving down. I'm not always downshifting when the notice appears.
Thanks for the comments,
Jeff
There is a tire size converter at Tirerack.com IIRC - you can see how far off your ratio is vs stock.
Thread Starter
Safety Car
Joined: Dec 2004
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From: Boca Raton, FL
St. Jude Donor '05-'06-'07-'08-'09-'10-'11-'12-'13-'14
Question: will this cause any harm/damage to the engine? Here's my reason for asking. Just put brand new Michelin PS tires on less than 500 miles ago and you can guess the rest.
Any responses to my question will be greatly appreciated.
Jeff
Race Director
Joined: Mar 2005
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From: Austin Texas
The tire size calculator I use shows;
285/35/19 @ 84.35" circumference &
345/30/19 @ 85.26" circumference, a 1.07% difference.
And with stock size fronts 1% difference in the rear diameter should not be enough to cause a problem.
285/35/19 @ 84.35" circumference &
345/30/19 @ 85.26" circumference, a 1.07% difference.
And with stock size fronts 1% difference in the rear diameter should not be enough to cause a problem.
Tech Contributor
Joined: Jul 2002
Posts: 14,950
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From: St. Louis, MO
St. Jude Donor '08
Jeff, I'd get it fixed. My car freaks out when I drive on my short 26" drag radials and does spooky things with active handling... If I forget to turn it off. It usually happens during lane change manuvers, I can feel the car applying the brakes and fighting me changing lanes.
I would not want to see what would happen if I had a real emergency with the mismatched tires that required the active handling.
Seriously, PM GTOdoug a fellow HP Sales customer. He has some tall front tires he's replacing for precisely this reason.
Burning Brakes
Joined: Feb 2006
Posts: 903
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From: Miami FL
Jeff, my car is over there now. They will be switching out wheels and tires shortly. The Tires that are over there are Bridgestone RE50A's. They are 255/40/18's which are 26" tall. I don't know if this will fix your problem, but I paid 450 new. They are used since Jan 15th. They have approx 2000 miles on them and look new. $200 bucks takes them. Tell them to referece this thread as I'm leaving town for 10 days and won't be able to communicate anything to them.
Dougie
Dougie
Thread Starter
Safety Car
Joined: Dec 2004
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From: Boca Raton, FL
St. Jude Donor '05-'06-'07-'08-'09-'10-'11-'12-'13-'14
I really don't want mismatched front and rear tires, I guess I'll get new fronts and sale the existing ones on the CF 
So, what size fronts should I get?
So, what size fronts should I get?
Race Director
Joined: Mar 2005
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From: Austin Texas
245/40/18F and 345/30/19R
Then your tire sizes shouldn't be causing a problem. You are stock diameter on the front and only 1.07% larger on the Rear.
Try this calculator;
http://www.1010tires.com/TireSizeCal...?action=submit
Le Mans Master
Joined: Sep 2004
Posts: 5,707
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From: Los Angeles
If the sizes given in your original post were correct;
245/40/18F and 345/30/19R
Then your tire sizes shouldn't be causing a problem. You are stock diameter on the front and only 1.07% larger on the Rear.
Try this calculator;
http://www.1010tires.com/TireSizeCal...?action=submit
245/40/18F and 345/30/19R
Then your tire sizes shouldn't be causing a problem. You are stock diameter on the front and only 1.07% larger on the Rear.
Try this calculator;
http://www.1010tires.com/TireSizeCal...?action=submit
I'm showing 5.55%
Race Director
Joined: Mar 2005
Posts: 10,399
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From: Austin Texas
The difference between STOCK REAR size and his reported REAR size is 1.07%. He claimed STOCK FRONT size so there won't be a difference.
The Active Handling, Traction Control (and Engine Drag Control?) depends on STOCK front to rear stagger. You can run any wheel/tire size Front to Rear that fits in the wheel wells if you maintain the stock stagger.
The STOCK Front to Rear stagger is 4.25%.
The Active Handling, Traction Control (and Engine Drag Control?) depends on STOCK front to rear stagger. You can run any wheel/tire size Front to Rear that fits in the wheel wells if you maintain the stock stagger.
The STOCK Front to Rear stagger is 4.25%.
Last edited by haljensen; Jun 1, 2007 at 07:23 PM.