Idle problem, need help
Thread Starter
6th Gear
Joined: Jun 2010
Posts: 6
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Idle problem, need help
I have a new LS3 crate engine with stand-alone harness. It seems to me that when this engine is first started, it revs to 2000 rpm for 1-2 seconds then immediately drops to idle, around 850 rpm. This is quite good. Then when it gets hot, on a restart, it revs to 2000 but does not drop back to idle. What should I be looking for? Any ideas while I'm waiting for a scan tool?
Le Mans Master
Joined: Aug 2005
Posts: 5,375
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From: CA.
St. Jude Donor '13-'14-'15
Typically it's the idle air control as mentioned--"desired airflow" in EFILIVE--It is scaled by coolant temerature---
Also remember that when the engine is 1st started either dead cold or warmed--The ECM is in "open loop" mode---when dead cold the coolant must reach apprx 140* before it changes to "closed loop" afrer warmed it switches to a timer-usually around 20 seconds before it will change into closed loop--- Many times especially with long tubes--the open loop fuel mustt be leaned down to avoid erroneous data and to get rid of start-up surging/dying/hanging
Also remember that when the engine is 1st started either dead cold or warmed--The ECM is in "open loop" mode---when dead cold the coolant must reach apprx 140* before it changes to "closed loop" afrer warmed it switches to a timer-usually around 20 seconds before it will change into closed loop--- Many times especially with long tubes--the open loop fuel mustt be leaned down to avoid erroneous data and to get rid of start-up surging/dying/hanging
