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Re: Closed loop lambda problem

Posted: Tue Jul 10, 2018 3:52 pm
by iceman_n
awesome info Alex, didnt know that different injector drivers will have different dead times....

Re: Closed loop lambda problem

Posted: Tue Jul 10, 2018 4:11 pm
by iceman_n
ID Injectors dead times

https://www.hamotorsports.com/injector- ... rates.html


Injector dead times, offsets, flow rates, and slopes for ID injectors. Note that all charts are rated at FUEL PRESSURE DIFFERENTIAL across the injector, not simply rail pressure.

Re: Closed loop lambda problem

Posted: Tue Jul 10, 2018 4:40 pm
by stevieturbo
iceman_n wrote:ID Injectors dead times

https://www.hamotorsports.com/injector- ... rates.html


Injector dead times, offsets, flow rates, and slopes for ID injectors. Note that all charts are rated at FUEL PRESSURE DIFFERENTIAL across the injector, not simply rail pressure.
But if the FPR and fuel system is working correctly...your injector should always be seeing a single pressure differential across it.

Re: Closed loop lambda problem

Posted: Tue Jul 10, 2018 6:32 pm
by iceman_n
When an engine is idling, there is a vacuum in the intake manifold. This vacuum pulls fuel out of the injectors, and increases the effective pressure across the injector to a pressure higher than the rail pressure itself.

When a supercharged or turbocharged vehicle is in boost, the pressure inside the manifold is trying to push fuel back into injector, resisting the flow and decreases the effective fuel pressure below that of the rail.

Re: Closed loop lambda problem

Posted: Wed Jul 11, 2018 5:58 am
by stevieturbo
iceman_n wrote:When an engine is idling, there is a vacuum in the intake manifold. This vacuum pulls fuel out of the injectors, and increases the effective pressure across the injector to a pressure higher than the rail pressure itself.

When a supercharged or turbocharged vehicle is in boost, the pressure inside the manifold is trying to push fuel back into injector, resisting the flow and decreases the effective fuel pressure below that of the rail.

Which is why it is commonplace to run a referenced FPR. So there is always a constant pressure delta across the injector.

So neither boost or intake vac will alter what is happening at the injector.

Re: Closed loop lambda problem

Posted: Wed Jul 11, 2018 12:56 pm
by katana
Or you create the fuel MAP without a referenced FPR with lower values due to vac. and add compensations based of the MAP sensor to enrich under boost - all quite simple and effective!