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By AlexE

Im waiting for some components for PNP board (Transi Productions) for NBFL Mazda MX5 and thinking how to program EVAP purge solenoid.

I cannot find any specific map for this function
By dazq
AlexE wrote: Sat Mar 18, 2023 12:18 pm Hello,

Im waiting for some components for PNP board (Transi Productions) for NBFL Mazda MX5 and thinking how to program EVAP purge solenoid.

I cannot find any specific map for this function
There is no evap/purge feature.
Most people remove the whole thing and use a catch tank.
Alternatively you could configure the programmable outputs to trigger the solenoid under a pre set condition/s.
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+1. Every make has different control, some quite complicated, so there is no generic feature. If required to retain, then the purpose for retaining control should be examined to configure a system to do whatever is necessary to meet required goals.

This could be simplified AuxOut, while I've heard some with tight emissions requirements have built their own standalone control, enabled by the main ECM. This is all left to you and your specific requirements, as one size does not fit all.
By AlexE
In case of MX5 I think simple feature will be ok, just to prevent fuel pressure buildup. Maybe opening valve for a second from time to time, when engine warm will be ok? Any suggestions how to to program such feature?
User avatar
As @dazq mentioned, from the Wiki: ... le-outputs

Keep in-mind, if wanting to use an existing unused higher-current output (e.g., Boost output) to control the valve, the existing function on that output must be moved to an unused pin, before assigning use to PO. Search for "pin reassign" posts here for details such as reassigning the Fuel Pump output for simple procedure examples.
By AlexE
thanks for answers, I suspected cascade of conditions can be solution

I will be experimenting as soon as I get car running :D
By AlexE
Hello again,

as I managed to get car running quite well I started to experiment. And situation is as follows:

If I set 3 conditions ( 3,4,5 ) all to virtual it seems to work. I get short pulse on output 5 once a 3 sec
purge virtual.jpg
purge virtual.jpg (157.74 KiB) Viewed 1227 times
but if I assign pin to condition 5 (D39 in my case) Output5 comes on and stays on

what have I missed?
User avatar
Different ways to approach this, and cross-check as you go, e.g., is your AFR Target (not AFR) always over 14? Or, why Rule 4 at all? I would also consider that if Rule 3 & 4 are off, there is nothing to check and could be either, so perhaps 5 turns it on for 0.1s constantly. I do not pretend to know all the intricacies of these functions in a version of code, so I simplify as much as possible, try to avoid chaining functions, and test how it works with other parameters if it's not doing what I need.

Having said all that, I do not know specifically what you are trying to achieve (goals and conditions), so I cannot make recommendations.
By AlexE
AFR target >14 and RPM <4000 was my first rough idea of conditions to enable Purge -> cruise. I dont want to have Purge when accelerating or with higher loads. I can use also MAP value for instance, lower than say 50kPa.

3 rules to handle was from wiki you gave me link to (shift light), with just minor modifications.

My question is why just changing from Virtual to real pin changes behaviour

do you have any other idea to handle EVAP that works?
User avatar
Again, depends on the goals of the control. Some purge to atmo with key-on. Some use only higher-load, others higher-rpm, avoiding a substantial change in Lambda. Some condition any of that with fuel tank pressure. Others follow the OEM scheme (as much as possible) for whatever benefits that may have. Some use a vented gas cap and remove it. :lol: Some to the air filter housing, and others to the manifold. What is your goal with it?

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