SR Idle Issue - Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum

GripSpec · 11-13-2016, 07:30 PM

Having issues with my SR Idle. It consistently hangs at around 1.5k for 3-4 seconds after coming to a stop. In the video you can see where I push the clutch causing the idle to drop, then it revs back up to 1.5k and hangs for a bit, then finally drops again. One other odd thing, if I push the clutch the revs will stay at 1.5k until I come to a complete stop, no matter how long that takes). When it is warm out the idle will drop pretty low (550-600 rpms), but when it is cooler out (as it was in the video), the idle will only drop to 1k. When I let off the throttle to shift, it also feels like the revs hang for a moment before dropping. Anyone have any ideas of what could be causing these symptoms?

Kingtal0n · 11-14-2016, 11:23 AM

you might be using an automatic ECU on a manual transmission car,

something to do with the ECU probably watching the VSS and adding idle speed to keep the engine from bogging. It seems computer related. It could also be a learned feature, if you have electric fans that bring the idle down, or other electronic power drains which lower engine RPM, the ecu will LEARN to keep the idle up due to the drain... and then when the engine is cold (fans are not on) the extra airflow is still added ( the ecu doesn't know when the fans are on or off ) and so the idle goes higher.

Tyler_240 · 11-14-2016, 02:49 PM

Is your neutral position switch wired up? I had issues timing my car until I got it fixed up.

Nissan2nr22 · 12-07-2016, 01:49 PM

Quote:

Originally Posted by Kingtal0n

you might be using an automatic ECU on a manual transmission car,

something to do with the ECU probably watching the VSS and adding idle speed to keep the engine from bogging. It seems computer related. It could also be a learned feature, if you have electric fans that bring the idle down, or other electronic power drains which lower engine RPM, the ecu will LEARN to keep the idle up due to the drain... and then when the engine is cold (fans are not on) the extra airflow is still added ( the ecu doesn't know when the fans are on or off ) and so the idle goes higher.

Had many SRs and JZs i either converted from auto to manual or were converted with auto ecu, never once an issue like this because of the ECU

11-13-2016, 07:30 PM	#1
GripSpec Leaky Injector Join Date: Dec 2007 Location: Richmond, VA Age: 37 Posts: 93 Trader Rating: (5) Feedback Score: 5 reviews	SR Idle Issue Having issues with my SR Idle. It consistently hangs at around 1.5k for 3-4 seconds after coming to a stop. In the video you can see where I push the clutch causing the idle to drop, then it revs back up to 1.5k and hangs for a bit, then finally drops again. One other odd thing, if I push the clutch the revs will stay at 1.5k until I come to a complete stop, no matter how long that takes). When it is warm out the idle will drop pretty low (550-600 rpms), but when it is cooler out (as it was in the video), the idle will only drop to 1k. When I let off the throttle to shift, it also feels like the revs hang for a moment before dropping. Anyone have any ideas of what could be causing these symptoms? Last edited by GripSpec; 11-14-2016 at 07:40 AM..

11-14-2016, 11:23 AM	#2
Kingtal0n Post Whore! Join Date: Jul 2005 Location: South Florida Age: 41 Posts: 4,828 Trader Rating: (17) Feedback Score: 17 reviews	you might be using an automatic ECU on a manual transmission car, something to do with the ECU probably watching the VSS and adding idle speed to keep the engine from bogging. It seems computer related. It could also be a learned feature, if you have electric fans that bring the idle down, or other electronic power drains which lower engine RPM, the ecu will LEARN to keep the idle up due to the drain... and then when the engine is cold (fans are not on) the extra airflow is still added ( the ecu doesn't know when the fans are on or off ) and so the idle goes higher. __________________ 5.3/4l80e/turbo 240sx playthrough: tinyurl.com/4l80er

11-14-2016, 02:49 PM	#3
Tyler_240 Zilvia Member Join Date: Feb 2005 Location: Gainesville, FL Posts: 239 Trader Rating: (9) Feedback Score: 9 reviews	Is your neutral position switch wired up? I had issues timing my car until I got it fixed up. __________________ S13 SR20DET 12.9 ET @ 111 MPH