Page from a manual discussing warm idle and spark timing strateg…

9. WARM IDLESTRATEGY # 9 9.1 Fuel Control The conlrol module recognizes Warm ldle slralegy when [M TPS indicates closed lhmnle VSS lndlcales zem vehicle speed, and ECT slgnals warm engine, The oonlrol module witches to Closed Thrallle Ioakvup labls. lnjscllan pulses are short because the englne needs to dellver only enuugh powerlo keep llsell mnnlng. Usually lna oxygen sensor oonllnuas lo dellver swilchlng wllagesr so me engine operales closed loop, ll ma eonlrol module sees no change In mo swrlcnlng voltage lor l5 sec onds, ll goes lo open loop. Tnan ll ll sees Mo exnadsl-gas ox- ygen varralrons, lne conlrol module swncnes back lo closed loop The control module shuts O the EGR The Thelmaclol wlll wmlnus lo diverl dawnslmam bu! ldla oonlmues lav sevelal mlnules, me Thermaclor wlll bypass to avoid overneaung lne ulalyllc convorler. 9.2 Spark Timing Warm ldle allows lhe exnaosl gasses lo cool, ll prolonged. Warm ldls rncrpascs ornlsslons M M: and (:0. Few Warm ldleslralegy increases lne lempsmxuls ol me axhaus| gasses ldr holler ermssmn conlrol Spark llmlng ls retalded gradually aboul 5 aller l minule pl Warm Idle. Spark relard ls cumblned with rncreased Tl'llollle Arr Bypass.