wont idle when at temperature
10-06-2014, 08:13 PM
#1
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wont idle when at temperature I got my car up and running and drove it to night. Cold the car will fire right up and idle but after it gets to temperature the idle jumps and it starts die. my question is should i just turn up the idle screw or should i drill the hole in the throttle body plate a little bigger? It got a tune for the cam i have and other then not idling at temp it runs great
10-07-2014, 02:51 AM
#2
Who tuned the car? You do not want to mess with the idle screw or the throttle hole unless you have to. Their are other ways to resolve this first. You say it starts and idles fine when cold but once warm it starts to idle bad correct?
Sounds like Idle learn. The pcm waits until a defined temp before attempting to learn proper IAC count for 4 car conditions. 1.) Park/neutral with no ac. 2.) Park/neutral with ac on. 3.)In gear with no ac and finally 4.) In gear with ac on.
Since you've changed cams the idle is different. It's trying to use the old IAC learned info. If your tuner isn't around to scan for IAC counts you can try this. Unplug the battery and wait 30 seconds. Plug the battery back in. Start the car and let it warm up. Once it reaches operating temp it will try to learn proper Idle in park. Have the ac off during this time and just let it run. It might stall...just restart and let it keep trying for a bit till it settles down. (it will hunt for the idle and you'll hear the engine surge up and down as it does so.) If it settles let it run a moment then turn ac on. It will start surging again trying to find it's idle....it may stall. Just restart and keep going till it learns it. Then turn ac off and wait a moment...put it in gear (with your foot on break). Let it hunt for idle again. After that turn ac on while still in gear and let it learn it's idle.
Hopefully your cams not to radical and this is all you need to do. If not, then your tuner will need to see what IAC counts are and go from there. It may need the idle screw messed with a little but with out having a way to scan and see IAC counts your just messing around in the dark messing with the idle screw and throttle blade hole otherwise.
Sounds like Idle learn. The pcm waits until a defined temp before attempting to learn proper IAC count for 4 car conditions. 1.) Park/neutral with no ac. 2.) Park/neutral with ac on. 3.)In gear with no ac and finally 4.) In gear with ac on.
Since you've changed cams the idle is different. It's trying to use the old IAC learned info. If your tuner isn't around to scan for IAC counts you can try this. Unplug the battery and wait 30 seconds. Plug the battery back in. Start the car and let it warm up. Once it reaches operating temp it will try to learn proper Idle in park. Have the ac off during this time and just let it run. It might stall...just restart and let it keep trying for a bit till it settles down. (it will hunt for the idle and you'll hear the engine surge up and down as it does so.) If it settles let it run a moment then turn ac on. It will start surging again trying to find it's idle....it may stall. Just restart and keep going till it learns it. Then turn ac off and wait a moment...put it in gear (with your foot on break). Let it hunt for idle again. After that turn ac on while still in gear and let it learn it's idle.
Hopefully your cams not to radical and this is all you need to do. If not, then your tuner will need to see what IAC counts are and go from there. It may need the idle screw messed with a little but with out having a way to scan and see IAC counts your just messing around in the dark messing with the idle screw and throttle blade hole otherwise.
10-12-2014, 01:00 PM
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If by "jumps" you mean surging, start with your idle AFR
(true AFR, not necessarily equal to indicated AFR, and
prone to false trimming on big-cam motors or even mild
ones with long tubes). Also clean the over/under speed
spark adder tables and maybe give some more timing
(but you ought to tune idle with the adaptive spark
off, so you deal with the worst case, the slow idle RPM
loop trying to stabilize a laggy over-enriched motor).
(true AFR, not necessarily equal to indicated AFR, and
prone to false trimming on big-cam motors or even mild
ones with long tubes). Also clean the over/under speed
spark adder tables and maybe give some more timing
(but you ought to tune idle with the adaptive spark
off, so you deal with the worst case, the slow idle RPM
loop trying to stabilize a laggy over-enriched motor).