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Old 12-28-2004, 10:27 AM   #1
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Default RPM loss

OK so here is the newest problem! After shovelling about the 21" of snow we got I tried to back out of the driveway...yah right. The traction light kept coming on because I was obviously slipping. However a few seconds after the traction control light came on while I continuted to try to go up the hill the engine RPM dropped right down to about 1500 and the car started shuddering really badly. Giving it more gas did absolutely nothing it was like a dead pedal. I did notice however that the boost gauge kept increasing the more gas i gave it but the engine just continued to shudder and stay at about 1500 RPM....any thoughts guys?
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Old 12-28-2004, 10:46 AM   #2
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Sounds like traction control kicked in an neutered the power output. The car will actively apply the brakes as well if you continue to slip.
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Old 12-28-2004, 02:13 PM   #3
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thanx.
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Old 12-28-2004, 02:16 PM   #4
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Will TC make the engine shudder, though? I don't have experience with TC, but that sounded kinda like a mis-fire.
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Old 12-28-2004, 03:37 PM   #5
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Quote:
Originally Posted by jwikoff99
Will TC make the engine shudder, though? I don't have experience with TC, but that sounded kinda like a mis-fire.
Yes, and its a horrible feeling.
The optional Traction Control System (TCS), option code NW9, also monitors rear wheel speeds and compares the rear wheel speeds to the speed of the front wheel speeds. If excessive front wheel speed is detected in either front wheels the TCS will be activated. The TCS uses the following to improve traction and vehicle stability:

Engine fuel control
Engine timing control
Front brake intervention

The traction control system uses the antilock brake system in conjunction with the powertrain control module (PCM) fuel and ignition controls to limit drive wheel slippage during acceleration. The PCM controlled portion of the traction control system reduces engine torque by any or all of the following methods:

Retarding the spark timing
Altering the air/fuel ratio
Altering the boost PWM (VIN 1)
Shutting OFF up to 3 injectors (sounds like a misfire)
To determine the amount of torque reduction required, the PCM monitors the TCS Desired Torque PWM signal from the electronic brake and traction control module (EBTCM). The PCM also provides a TCS delivered torque PWM informing the EBTCM of how much torque is being produced by the engine. The Desired Torque display on the scan tool indicates the amount of engine torque requested by the EBTCM. With the traction control inactive, the Desired Torque should vary between 99 and 100 percent . The Desired Torque display on the scan tool is not the PWM duty cycle.
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Old 12-28-2004, 03:47 PM   #6
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Very good PDad.

That is exactly why we disconnect the wheel speed sensors before doing burnouts before 1/4 race runs.

It'* one smart car.....GM protecting the transmission from warranty claims.

Even turning off the TCS button will not disengage this safety feature. It only really disables the braking part of it and delays it for a short time for getting out of mud or snow situations.
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Old 12-28-2004, 03:54 PM   #7
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Quote:
Originally Posted by 2000SilverBullet
Even turning off the TCS button will not disengage this safety feature. It only really disables the braking part of it and delays it for a short time for getting out of mud or snow situations.
I have been thinking of a way to disable the wheel speed sensors without pulling the plugs.
It has to be fail safe yet functional and easier than pulling the plugs.

Its really too bad that the existing tc switch cant be programmed to do just that.
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Old 12-28-2004, 04:17 PM   #8
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Quote:
I have been thinking of a way to disable the wheel speed sensors without pulling the plugs.
It has to be fail safe yet functional and easier than pulling the plugs.
Use that Electrical ingenuity and go for it PDad.

Sure would be nice if we also had a switch for the Stabilitrak but leave the anti-lock functioning. Then we could really have some fun.
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