minimum pulse width? 60 lb injectors, $DA2

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dizwiz24
Posts: 54
Joined: Mon Jun 29, 2009 6:15 pm

minimum pulse width? 60 lb injectors, $DA2

Post by dizwiz24 » Tue Apr 15, 2014 4:45 pm

Does anyone have any recommendations on a minimum pulse width setting for 60 lb injectors?

The goal is to get more controllable fuel trims (ie. BLM's closer to 128), less split BLM's, etc.

I heard someone say once that you dont want a minimum pulse width below a certain value or it would cause issues

My cam is a 'mild' performance cam 224/236 114 LSA, so I'd like to believe better fuel control is still possible.

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dfddfd2
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Joined: Wed Feb 27, 2008 4:37 pm
Location: Burgaw, NC

Post by dfddfd2 » Wed Apr 16, 2014 5:06 am

I believe you're asking about injector "latency" or "dead time" or "lag time". It is based on battery voltage and there is usually a table in the ECU indexed by battery voltage for this value. Here is a link to a list of injectors and their lag times: Injector Lag Times

cliffharris
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Joined: Mon Nov 24, 2014 9:43 pm

Post by cliffharris » Mon Nov 24, 2014 10:38 pm

The minimum pulse width is programmed into the code by the factory engineers. It specifies the minimum pulse width that the ECM can produce reliably. It's basically a hardware limit because of the limitations of the injector driver transistor(s) and the injectors.

The ECM/PCM calculates the proper injector pulse width and then compares it to the minimum pulse width. It then uses whichever is LARGER. What that boils down to is that if you put in giant injectors your engine will idle really rich because the ECM can't reduce the injector pulse width enough to get the correct AFR.

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