DJ PC and closed loop FI questions
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Tourer
Joined: Jun 2010
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DJ PC and closed loop FI questions
With respect to a closed loop system, how does a fuel management device (like a PC) do anything if the original exhaust air sensor eliminator is not used?
As I understand it ..... an EPA approved closed loop FI system makes the air fuel mixture hold a constant ratio under all conditions.
So assuming no modifications to the system are made other than adding a fuel manager, how can it modify or correct an EPA lean bike?
It seems (to me with my limited knowledge of these systems) that even if you modify the exhaust and intake, this type of the closed loop system will still make the adjustments to hold the air fuel mixture at the mandated ratio ...... so if not wanting to use the sensor eliminator, do you cut into the air sensor output and add a mapped error signal to it before it gets to the ECM, to trick it into running a fatter/different mixture ratio?
Additionally, what can the PC 'EX versions' do for a California bike ....... even if the air sensor 'is' eliminated?
I've used the search function but end up with too much info to sort through .......
So, I'm hoping somebody can either correct my understandings and/or shed some light on what is the benefit of using a PC on a street legal, closed loop FI bike in California ..... or possibly anywhere for that matter.
As I understand it ..... an EPA approved closed loop FI system makes the air fuel mixture hold a constant ratio under all conditions.
So assuming no modifications to the system are made other than adding a fuel manager, how can it modify or correct an EPA lean bike?
It seems (to me with my limited knowledge of these systems) that even if you modify the exhaust and intake, this type of the closed loop system will still make the adjustments to hold the air fuel mixture at the mandated ratio ...... so if not wanting to use the sensor eliminator, do you cut into the air sensor output and add a mapped error signal to it before it gets to the ECM, to trick it into running a fatter/different mixture ratio?
Additionally, what can the PC 'EX versions' do for a California bike ....... even if the air sensor 'is' eliminated?
I've used the search function but end up with too much info to sort through .......
So, I'm hoping somebody can either correct my understandings and/or shed some light on what is the benefit of using a PC on a street legal, closed loop FI bike in California ..... or possibly anywhere for that matter.
Seasoned HDF Member
Joined: Aug 2009
Posts: 9,243
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From: west Michigan
When I installed a Techlusion fuel minder on a BMW oilhead several years ago, I was told that the unit altered the duration of the "signal" between the ECU and the Injectors which resulted in a longer "fuel spray" duration. IE, the Techlusion worked "between" the ECU and Injectors and didn't affect the ECU. I'm guessing that the DJ PC works on the same principle.
Stellar HDF Member
Joined: Dec 2009
Posts: 2,035
Likes: 8
From: Western Canada
I might be wrong about this but
my understanding is this, the ecm is in an open loop at low rpm to allow for a richer AFR and take off power and goes into the closed loop at mid range for cruising and then back to open loop for 'again a richer AFR for full throttle operation. A PC or most other fuel management systems intercept the power request's that come in the form of electrical power or volt's via the throttle and then send them to each cylinder injector depending on the map and the engine requirements. Thereby effectively eliminating the stock ecm fuel control entirely.
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Tourer
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Aahaa ...... that makes sense (in both replies above).
So that's how/why a fuel management can improve the EPA lean at the most critical times for better engine life 'and' performance.
I assume the PC EX models (for California) that have a blocked map area to comply with C.A.R.B., probably block the mid throttle position areas. (???)
I can now see how the mandated air fuel ratio can be altered (when not at mid throttle) without having to block off the air sensor.
Thanks guys!!
This was 'really' bugging the hell out of me .........
So that's how/why a fuel management can improve the EPA lean at the most critical times for better engine life 'and' performance.
I assume the PC EX models (for California) that have a blocked map area to comply with C.A.R.B., probably block the mid throttle position areas. (???)
I can now see how the mandated air fuel ratio can be altered (when not at mid throttle) without having to block off the air sensor.
Thanks guys!!
This was 'really' bugging the hell out of me .........
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