High rev issues when slowing down and very rough running
What DTC's are set???
SOUNDS like IAC disconnected or otherwise not right, Check the connector on the top rear side of the induction module, BUT download DTC's as a very first step. DTC P0505 is IAC
The ECM controls engine idle speed by moving the IAC to open or close a passage around the throttle plate. The IAC motor has two windings and the ECM sends voltage pulses to the proper motor winding of the IAC to either cause the pintle to move in or out of the IAC a given distance for each pulse received. Idle speed is increased as the ECM retracts the pintle, allowing more air to flow through the throttle body and idle speed is decreased when the ECM extends the pintle, allowing less air to flow through the throttle body. The IAC position is measured in steps by a computer program called the H-D DIGITAL TECHNICIAN. A fully retracted pintle and open passage around throttle plate is indicated by a high number of steps and is correlated to an increased amount of air flowing through the throttle body. Conversely ZERO steps represents a fully extended pintle which is a fully extended pintle and a closed the passage around the throttle plate, which is an abnormal condition. The ECM resets the IAC each time the ignition is turned off, by sending sufficient pulses to extend the pintle and effectively close the throttle body. The reference point used by the ECM is the fully extended value in steps from which a set number of counts (steps) are then calculated by the ECM for use in setting the proper idle speed and IAC position. WARM IDLE SPEED is ECM controlled and cannot be adjusted except with Digital Technician. When the engine is stopped, the IAC pintle extends and then retracts to a fixed "Park" position for increased airflow and idle speed during the next engine start sequence. This key OFF reset procedure takes 10 seconds to perform. A special test lamp may be used to test the IAC operation. The color of the lights is not relevant to IAC operation. In NORMAL circumstances when the key is turned ON the test lights will alternately flash and then remain steady on to confirm ECM signals. When the key is turned OFF the lights should alternately flash and go out after the 10 second reset procedure. IF one or more of the lights fails to illuminate during key the ON/key OFF/key cycle a problem is indicated and there is also a remote possibility that one of the circuits is shorted to voltage. This would have been indicated by a steady light. In these circumstances with the Ignition Switch OFF, disconnect the ECM and turn the ignition ON again and probe the terminals to check for this shorted condition and fix it by repairing a faulty ECM connection or by replacing the ECM.
Diagnostic Trouble Code P0505 sets if theidle RPM is +200 or -200 from the preset idle speed and the IAC motor is at zero steps or at maximum steps for greater than 5 seconds. P0505 may occur with others for a multiple code situation and if so the other codes must be resolved first before dealing with P0505.
Engine Idle Diagnostic Tips
Engine idle speed can be adversely affected by the following:
1.an intake air leak;
2.improperly adjusted throttle stop or a misfiring cylinder;
3.leaking injectors will cause fuel imbalance and poor idle due to different air/fuel ratios in each cylinder.
(To check for leaky injectors, first remove the air cleaner and then with the throttle wide open, turn the key ON for 2 seconds and then OFF for 2 seconds five consecutive times and look fro any sign of fuel in the induction system. If there is any you will need to replace the fuel injector(s).;
6.excessive oil in the crankcase (oil sumping);
7.TPS reading greater than 1% (possibly caused by a throttle cable misadjustment);
8.battery voltage reading of less than 9 volts;
9.a VSS greater than 0 will disable idle speed control; and
10loss of battery power to ECM pin 31.
May 23, 2014 |
Harley Davidson FLHTCUI Electra Glide...