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ayjayef

Master Fuel - math check please.

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Okay, so I have someone else's fuel table (similar setup but not the same) and want to compare.

My Master fuel is set to 4ms (running E85)

His is set to 10ms (running pump)

If I multiply his Fuel Table by 2.5 (for the 2.5 times difference in master fuel) and then multiply by 1.35 (for 35% E85 difference)

Should the numbers compare?

 

Adding to my confusion, I have larger secondary injectors which are set to 63.9% in the Sec Injection Staging Table @ 40% TPS and I have 1.770 Sec/Pri Ratio in the staged injection where he runs  the same injectors top and bottom) so is 50/50 and 1/1.  

Does that change the my fuel numbers before the Sec Injection Staging comes in?

I'm struggling to get fuel numbers that make sense.

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Im not quite understanding what you are trying to achieve here.  Somebody elses fuel map is not going to be useful to you, you are meant to just tune yours until the measured lambda is running close to the target under all operating conditions. 

The staged injection setup should not affect the numbers in the main fuel table or the amount of fuel injected provided the sec/pri ratio setting is correct.

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If I had a WRX there are plenty of base map files in the PCLink software which are useful to other owners.

I don't own a WRX so wanted to compare his map (same bike, similar setup) as I'm having trouble starting the bike and can get it running by randomly dumping lots of fuel in the Crank Enrichment table (similar to pouring fuel in the air cleaner of a hard to start car).

It now starts nearly reliably at ECT 20C with 140% crank enrichment and starts at 40C-50C with 120% but restarting when it's hotter than that is unlikely.

 

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Ok so if you only have a startup problem then you shouldnt be messing with your main fuel table.  I would be looking at pre-crank prime, crank enrichment and maybe check if IAT is seeing a "heat soak" effect during warm starts.

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Hi Adam,

my urge to get some comparable numbers in the main fuel table was to see what the crack enrichment actually was as it's a percentage of that table.

 

Pre-crank prime (because I'm using "Key-On") seems less useful to me as turning the key off and on disconnects the PCLink and induces additional lag reconnecting before starting the engine.  Maybe I need to look at triggering pre-crank prime using the starter switch? Trickier to get to in loom but might make sense.

Crank Enrichment @ 70C was set high and still wouldn't work.  At what point do I hydraulic a motor adding too much fuel?

Heatsoak should be okay, IAT was around 20C in the plenum but throttle bodies, valves, head etc would be higher when ECT is 70C

 

Is there a rule of thumb with E85 vs petrol volumes during prime and enrichment?

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22 minutes ago, ayjayef said:

my urge to get some comparable numbers in the main fuel table was to see what the crack enrichment actually was as it's a percentage of that table.

No its not a percentage of the number in the fuel table, it is a percentage of the final calculated pulsewidth.  So it includes master fuel and MAP etc.  So lets say both your engine and his engine had the fuel tables tuned so they where both idling at 1.0lambda.  But your fuel table had numbers of 80 in it and his had numbers of 20.  If both had the crank enrichment set to 20% then you would get 20% extra fuel and your lambda would be 0.8 on both engines - the different fuel table numbers have no effect.

 

28 minutes ago, ayjayef said:

Is there a rule of thumb with E85 vs petrol volumes during prime and enrichment?

No rule of thumb but especially at lower temps the difference is large.  Say you will typically need 2 times more enrichment with E85 compared to petrol.

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42 minutes ago, Adamw said:

No its not a percentage of the number in the fuel table, it is a percentage of the final calculated pulsewidth

That makes sense, ta.

 

41 minutes ago, Adamw said:

No rule of thumb but especially at lower temps the difference is large.  Say you will typically need 2 times more enrichment with E85 compared to petrol.

 

Bingo!  Yes, I had to near double his crank enrichment numbers to get it cold started.  Now I know that's some sort of "normal" I'll be less worried about how much fuel I dump in there.

 

Thanks Adam.

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