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DIY Fuel injection thread.


yoeddynz

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yeah i mostly want it for the relays, as if need be i can fit fused relays. 

problem with OEM, i have the fusebox from the car my engine came out of, an 80s corona GT, and although on top it looks fine albeit a little big. it has propriety plugs on the bottom and no simple way to wire the relays and fuses in a custom way. though if you find an oem option that does work this way do let me know. 

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Relays in the appropriate places have fixed all Problems, once again thanks all that provided their help! 

I've just done it all with fly leads to confirm the fix and will now look into a proper relay box and wire it with correct gauge wiring etc. 

One step closer to boost cruising! 

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Yeah I just wired in one of those fuse boxes and it's come up really good.

It doesnt show on the pics but it's got a bottom cover as well so there arent wires spewing everywhere. It's  tidied up stuff under my dash considerably.

(But my wiring still looks like garbage)

I've been on a rewiring mission to tidy things up as well as having lost 16kg worth of junk from the car so far. 

Engine is nearly ready to start again, will be really interesting to see the cam timing / MAF / MAP / exhaust pressure relationship.

Just running MAF in observation mode for starters to build a calibration for it. But it's exciting to see some new sensors coming to life :D

bq1oymh4.npp.jpg

 

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Barometric compensation:

 

How much of an effect does altitude have on an EFI engine? From my days flying I know that with a carb the mixture richens up significantly with altitude and thus leaning out is required.

 

I've just installed a second MAP sensor on the Starlet, taking a reading directly from the airbox (post-filtration to minimize risk of contamination - reading seems to be pretty stable under all operating loads so it seems like a reasonable location). I've yet to climb any big hills with it to set the compensation table.

 

Have any of you guys done this on your cars?

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Looks like the car needed about 0.7% less fuel at 400 m when compared to sea level, so the addition of the barometer seems to be somewhat useful. I'll do some more adjusting using the baro table on the trip up to Auckland this week, there are a fair few decent climbs on the way.

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From what I can tell, an engine draws vacuum relative to atmospheric - thus it will show a different MAP value for the same loading condition when at different altitudes. By using barometric correction you can minimize/eliminate this problem.
 

Ie you might be at 60 kPa abs. when cruising at 3,000 rpm at sea level. If you climb to 1000 m asl then you could potentially be at 50 kPa abs. for the same loading condition - thus putting you in a different part of the tune map.

 

It gets kind of tricky to think about. I'm not too sure how the megasquirt would cope with huge changes in MAP at idle speed when up at high altitude.

 

I would also assume that the change of MAP at altitude isn't linear as you certainly can't pull a vacuum below 0 kPa abs, so the rate of change in MAP would decrease with an increase in altitude.

 

Also you would have tuned your car for max power at a MAP of 100 kPa (or thereabouts), if you are at high altitude then you may only reach 85 kPa at max throttle - potentially putting you near your cruise section of your fuel table and running too lean for the throttle settings, requiring more fuel. But then also the volumetric efficiency of the engine would also change with the atmospheric pressure, causing more buggery.

 

hmmmmm

 

/Rambling on with incoherent thoughts

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From my understanding MAP sensors measure absolute pressure, that being pressure above a total vacuum (like in space). Bearing that in mind, they should self correct for altitude in an NA application, and the point is moot in a forced induction application.

If you've mapped for partial load using MAP, then the ECU will theoretically use that part of the map even at WOT

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Looks like if I just set the fuel calculation mode to "percent baro" it should rescale the fueling to continually use the entire VE table under all conditions. Apparently Lycoming engineers reckon that a barometric correction table is not really needed as the fueling should be within 5% of calculated for all realistically encounterable conditions.

 

So I'll try that and see how it goes on the trip up to Auckland: Barometric correction off, primary fuel load: Percent Baro

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