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FJR Motorcycle Forums
Technical & Mechanical Problems
Fast Idle Circuit and FI Enrichment
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<blockquote data-quote="Fred W" data-source="post: 1043138" data-attributes="member: 3828"><p>The ECU adds the extra fuel during cold starts in the form of prolonged injector open time.</p><p></p><p>Even if the wax motor didn't add the extra bypass air to increase cold idle speed the ECU would be adding extra fuel during warm-up based primarily on the coolant temp sensor signal, but it is also affected by the increased intake air volume, which is calculated from the TPS signal and the Intake air pressure sensor.</p><p></p><p>The ECU also has a special Starting Injection condition where it squirts a bunch of fuel in <em>asynchronously</em> (not timed to crankshaft position) to aid in starting while cranking. This is the feature that can cause your engine to flood if you keep trying to start it over and over, or turn the engine off too soon after a cold start.</p><p></p><p>Basic injector duration is <em>always </em>being adjusted based on a few of the signals: intake air temp, engine rpm & TPS. Anyone else think that sensor might be important? Not as important as Seafoam, of course.</p></blockquote><p></p>
[QUOTE="Fred W, post: 1043138, member: 3828"] The ECU adds the extra fuel during cold starts in the form of prolonged injector open time. Even if the wax motor didn't add the extra bypass air to increase cold idle speed the ECU would be adding extra fuel during warm-up based primarily on the coolant temp sensor signal, but it is also affected by the increased intake air volume, which is calculated from the TPS signal and the Intake air pressure sensor. The ECU also has a special Starting Injection condition where it squirts a bunch of fuel in [I]asynchronously[/I] (not timed to crankshaft position) to aid in starting while cranking. This is the feature that can cause your engine to flood if you keep trying to start it over and over, or turn the engine off too soon after a cold start. Basic injector duration is [I]always [/I]being adjusted based on a few of the signals: intake air temp, engine rpm & TPS. Anyone else think that sensor might be important? Not as important as Seafoam, of course. [/QUOTE]
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FJR Motorcycle Forums
Technical & Mechanical Problems
Fast Idle Circuit and FI Enrichment
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