High idle on 350Z
07-03-2022, 11:43 AM
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High idle on 350Z
Hello i am new to the Z community and i wanted to do some basic maintenance to my car so basically i removed the throttle body and plenum for some carb cleaning.
Anyways
my camshaft sensors stopped working so i ended up changing them and an OEM crankshaft sensor(since everyone says to change them all at the same time) and since the car was not running i took the plenum off and cleaned it and the TB.
I realised after firing the car up that the tb was bad so i changed it (idle was high) and since than the idle never was the same
i did the relearn procedure ecu relearn etc etc.
But nothing works the idle stays stable at 1050rpm at idle
depending on the days sometime it stays at 1100
But it never fluctuates a lot
Any idea why it is like that (it wasnt before taking **** appart)
Oh and i forgot to mention that the purge volume controle connector was broken so i redid the connections (car was throwing code cause it was broken since I bought the car)
help help
it sounds like a vaccum leak but i have no hising sound and changed the tb gasket and plenum to make sure there was no leak (cause clutch in when shifting and the idle goes high and stays high for a sec before going down) ... i have p0507 p0442 and p0455
Anyways
my camshaft sensors stopped working so i ended up changing them and an OEM crankshaft sensor(since everyone says to change them all at the same time) and since the car was not running i took the plenum off and cleaned it and the TB.
I realised after firing the car up that the tb was bad so i changed it (idle was high) and since than the idle never was the same
i did the relearn procedure ecu relearn etc etc.
But nothing works the idle stays stable at 1050rpm at idle
depending on the days sometime it stays at 1100
But it never fluctuates a lot
Any idea why it is like that (it wasnt before taking **** appart)
Oh and i forgot to mention that the purge volume controle connector was broken so i redid the connections (car was throwing code cause it was broken since I bought the car)
help help
it sounds like a vaccum leak but i have no hising sound and changed the tb gasket and plenum to make sure there was no leak (cause clutch in when shifting and the idle goes high and stays high for a sec before going down) ... i have p0507 p0442 and p0455
Last edited by Andy garcia; 07-03-2022 at 11:47 AM.
07-14-2022, 04:49 PM
#2
What year is your Z? Are there any aftermarket mods like intake or test pipes? or Tunes?
Did you use *all* OEM sensors (CAM sensors included)?
Did you use an OEM throttle body?
Check over your PCV system carefully, if you removed the intake manifold & throttle body, then some of these hoses were messed with. It's possible you forgot to reconnect one. On the VQ35DE, there are multiple vacuum lines under/around the throttle body and lower plenum. Check all of these and make sure they are connected properly. The P0442 and P0455 codes are directly related to your EVAP system. You may have a leak, sticking purge valve, or clogged cannister. You did say your purge control harness plug was somehow damaged and you repaired it. Can you elaborate more on this? It sounds like your repair either failed or the valve itself is broken.
Do some simple vacuum leak tests with throttle body cleaner. Spray around your intake manifold and vacuum lines while the engine is idling. If there's an immediate change in idle, you found a leak. There's plenty of youtube videos covering how to do this.
Good Luck!
-Icer
Did you use *all* OEM sensors (CAM sensors included)?
Did you use an OEM throttle body?
Check over your PCV system carefully, if you removed the intake manifold & throttle body, then some of these hoses were messed with. It's possible you forgot to reconnect one. On the VQ35DE, there are multiple vacuum lines under/around the throttle body and lower plenum. Check all of these and make sure they are connected properly. The P0442 and P0455 codes are directly related to your EVAP system. You may have a leak, sticking purge valve, or clogged cannister. You did say your purge control harness plug was somehow damaged and you repaired it. Can you elaborate more on this? It sounds like your repair either failed or the valve itself is broken.
Do some simple vacuum leak tests with throttle body cleaner. Spray around your intake manifold and vacuum lines while the engine is idling. If there's an immediate change in idle, you found a leak. There's plenty of youtube videos covering how to do this.
Good Luck!
-Icer
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