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idlesurge [2011/08/18 09:14]
twdorris
idlesurge [2012/07/17 15:51]
dmertz
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   * a damaged diaphragm in the wastegate actuator   * a damaged diaphragm in the wastegate actuator
   * a damaged diaphragm in the power-brake booster   * a damaged diaphragm in the power-brake booster
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 You may find that screwing the BISS all the way in doesn'​t bring the idle speed down to idle speed configured in DSMLink/​ECMLink. ​ That means that some other path is allowing too much air to pass.  First make sure that there is no leakage into the BISS hole by covering the hole with your finger. ​ If the engine speed drops when you cover the hole, replace the BISS O-ring. You may find that screwing the BISS all the way in doesn'​t bring the idle speed down to idle speed configured in DSMLink/​ECMLink. ​ That means that some other path is allowing too much air to pass.  First make sure that there is no leakage into the BISS hole by covering the hole with your finger. ​ If the engine speed drops when you cover the hole, replace the BISS O-ring.
  
-Next, investigate possible problems with the Idle Speed Control (ISC) servo. ​ Open the ECU and [[Driver01|inspect for burned ISC driver chips]]. ​ If you find any, [[http://​www.ecmtuning.com/​product/​servicerequest|contact ECMTuning regarding repair of the ECU]]. ​ If there //are// burned drivers, it's quite possible that the damage was caused by ISC itself having a shorted coil.+Next, investigate possible problems with the Idle Speed Control (ISC) servo. ​ Open the ECU and [[Driver01|inspect for burned ISC driver chips]]. ​ If you find any, [[http://​www.ecmtuning.com/​product/​servicerequest|contact ECMTuning regarding repair of the ECU]]. ​ If there //are// burned drivers, it's quite possible that the damage was caused by ISC itself having a shorted coil.  Make sure you are using the correct O-ring to seal the ISC to the throttle body. An O-ring that's too thin might not seal, too think and it might not allow the ISC to fully close the airway.
  
 [[http://​www.youtube.com/​watch?​v=KibYz21IMA0|Test the coils in the ISC.]] (Note that the newer, more reliable, all-black ISCs normally measure about 39 ohms.) ​ Inspect the tip of the ISC for any physical damage. [[http://​www.youtube.com/​watch?​v=KibYz21IMA0|Test the coils in the ISC.]] (Note that the newer, more reliable, all-black ISCs normally measure about 39 ohms.) ​ Inspect the tip of the ISC for any physical damage.
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 +Test for proper operation of the ISC:  Turn off the ignition and reset the ECU by removing battery backup power for at least 10 seconds, then restoring battery backup. ​ Then, with the ISC unbolted from the throttle body but plugged in to the wiring harness, turn on the ignition and observe the movement of the ISC.  The ISC should fully extend, then retract slightly. ​ If the ISC just quivers a bit but doesn'​t really move, suspect a problem with the ISC, the driver circuits in the ECU, or the wiring. ​ If the ISC fully retracts instead of fully extending, there is a wiring problem, perhaps a mismatch between '90 and '91+ engine harness and ISC.  Using a '90 harness with a '91+ ISC, or vice versa, will cause the ISC to operate backwards.
  
 Strange behavior can result from a bad Fast-Idle Air Valve. ​ This is a coolant-temperature controlled air valve that provides some of the additional air needed for fast idle during engine warm-up. ​ This valve is integral to the throttle body, so test by substitution or by blocking the FIAV passage with a block-off plate. Strange behavior can result from a bad Fast-Idle Air Valve. ​ This is a coolant-temperature controlled air valve that provides some of the additional air needed for fast idle during engine warm-up. ​ This valve is integral to the throttle body, so test by substitution or by blocking the FIAV passage with a block-off plate.
idlesurge.txt ยท Last modified: 2016/01/12 18:41 by nickracer