tbourner Posted December 14, 2004 Share Posted December 14, 2004 What does it mean? Something to do with injector 'ON' time? After THIS thread, I thought I'm sure I've had a bang before and Ian C said it was probably because of high boost and 100% duty cycle on lift off. So why does that cause flames/bangs? Huge technical description to baffle me please!! Link to comment Share on other sites More sharing options...
SimonB Posted December 14, 2004 Share Posted December 14, 2004 It just means the percentage of the time available the injectors are injecting fuel for. So at 100% they are busy injecting fuel for the entire window available during the intake stroke and you can't get any more fuel in there. When you lift off suddenly the engine no longer needs all that fuel, but is already committed to injecting it so you get unburnt fuel in the exhaust gases, which ignite in the exhaust, causing pops and bangs. Link to comment Share on other sites More sharing options...
JamesG Posted December 14, 2004 Share Posted December 14, 2004 Not sure you already meant this in your description, but at 100% duty, the injector would be open *all* the time, not just for the window available for the intake stroke. Link to comment Share on other sites More sharing options...
SimonB Posted December 14, 2004 Share Posted December 14, 2004 Originally posted by JamesG Not sure you already meant this in your description, but at 100% duty, the injector would be open *all* the time, not just for the window available for the intake stroke. It's what I meant, just not what I said! . Perhaps I should have said it's the ratio of the time the injector is open to the time available until the next injection event. It's the valves that control when the fuel/air mixture gets into the cylinder of course. Link to comment Share on other sites More sharing options...
tbourner Posted December 14, 2004 Author Share Posted December 14, 2004 Originally posted by SimonB It's the valves that control when the fuel/air mixture gets into the cylinder of course. So that means your timing must be wrong to get a flame out the zorst? Link to comment Share on other sites More sharing options...
SimonB Posted December 14, 2004 Share Posted December 14, 2004 Originally posted by tbourner So that means your timing must be wrong to get a flame out the zorst? No, the timing usually refers to when the spark plug fires. In any case the mix of fuel and air is getting in to your cylinder at the right time, it's just got too much fuel in for that particular moment in time so some remains unburnt. Link to comment Share on other sites More sharing options...
Whitesupraboy2 Posted December 14, 2004 Share Posted December 14, 2004 U must of been around a car after you turned it off and smelt petrol, thats unburnt fuel vapours coming out the exhaust. normally u dont smell it coz ur driving I bought myself the Flamer control box, just never had chance to fit it. It best to have Decat for it too work. So will wait till i do the exhaust then watch out Link to comment Share on other sites More sharing options...
tbourner Posted December 14, 2004 Author Share Posted December 14, 2004 Dunno about that but recently noticed that after turning it off, there's a whif of smoke comes out the exhaust for a few seconds!! As if it's still running!! Link to comment Share on other sites More sharing options...
JamesG Posted December 14, 2004 Share Posted December 14, 2004 Originally posted by tbourner So that means your timing must be wrong to get a flame out the zorst? If you massively retard your timing, then the exhaust valve will open before the spark, and the unburnt air-fuel mixture will reach the exhaust. Cue big flames This is what anti-lag systems do. When the throttle is lifted, the timing is retarded and extra air is added. The air fuel mixture hits the hot exhaust and the explosion keeps the turbo spooled up. Link to comment Share on other sites More sharing options...
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