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DIY Fuel injection thread.


yoeddynz

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  • 1 month later...

I used a program ages ago, but it didn’t really have the correct symbols and wouldn’t let me make new features, so I drew what I wanted in draftsight, which is a program that can draw lines or whatever symbols you want

 

In the end I ditched the whole thing and had a single sheet of paper which described what each fuse was used for, this was when I rewired my car

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Off topic to the above, but. 

My cars exhaust noise is really sensitive to ignition timing. Like if I dont have enough timing its way louder and tinny sounding. 

And also the oxy sensor readings dont seem right when the engine is cold.
 Like it will say 16:1 when it is chokingly rich at the exhaust pipe.
So for ages its always been much louder when its cold, but I put it down to either an exhaust leak that closes up once hot, or... something. 

But so thought I'd experiment by adding some ignition timing when cold.
Annnnddd car is now way quieter when cold! And the air fuel ratios showed closer to what seems accurate, now shows at about 13:1
So I reduced my cold fuel enrichments until I was at my goal AFR again, and now my fuel usage when cold has decreased: 

xc4ktarq.gip.png

I'm gonna call that a win! 

I think its because when the engine is cold the fuel and air just hasnt mixed very well at all... Lots of the fuel will still be droplets that dont start evaporating until ignition has started. So it takes way longer to burn properly (relatively speaking)
Which explains both why it was louder and why oxy sensor readings werent right. 
As there is still uncombusted air and fuel exiting the exhaust port if you dont have enough timing.

I've always had on my mind that you need extra fuel for cold conditions but never thought about ignition at all.

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On 3/14/2018 at 06:27, ajg193 said:

The thing is, quite often it does start within 30 seconds on cold mornings, like the last few days.

 

I've checked over the wiring and there seems to be nothing wrong there.

I'll look into adjusting the warmup reading, not sure if I will be able to do it from Linux though.

Must be aliens.

Measure current? Heater will suck bulk juice, and should be easy to see if it's intermittent. I have a clip on meter which'll do DC, you can borrow. Won't even need to undo the wire to put ammeter in circuit.

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On 5/28/2018 at 21:47, Otodat said:

Not sure if this is the right place to ask but would anyone be able to recommend electrical schematic software that is easy to use and cheap or free to acquire?

Windows? Eagle PCB gets used a lot, is limited to small output PCBs for free version, which shouldn't affect schematic only. KiCAD is full on industrial, free, but may not meet your easy to use criteria. I've been meaning to learn it for a few years, but I have Protel muscle memory, and libraries.

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16 minutes ago, h4nd said:

Measure current? Heater will suck bulk juice, and should be easy to see if it's intermittent. I have a clip on meter which'll do DC, you can borrow. Won't even need to undo the wire to put ammeter in circuit.

Heater works fine, sensor gets hot as balls and whatnot.

Also managed to flatten my battery a few weeks back when twoddling about with the O2 sensors. Car is up in Auckland ATM and has been running fine, might get a 14point7 sensor and controller one day though.

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1 hour ago, ajg193 said:

All that work for 10 hp? Maybe it's not worth me going to ECU controlled ignition.. I wonder what their fuel savings are

8% more power is another way to think about it... Which isnt bad when you stop to think that it pays for itself over time with the economy difference.



 

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Well they didn't do EFI with old ignition in the test, might only be like 3 % extra with the ignition control.

 

Takes a hell of a long time to pay itself off. In my car's current form there is very little chance of the EFI ever paying itself off, but I justify it by saying it wasn't done for the money savings.

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13 minutes ago, Firetruck said:

Not when you half-ass it anyway

The thing is that the car already used very little fuel anyway (like 6.5 L/100 km on open road with carb, around 8.5 when thrashing it around town). Any gains you get on an engine that doesn't use mush in the first place won't really result in much monetary savings, even if you are saving 15 %. Changing to EFI has given maybe a 0.75 L/100 km saving on open road and about 1.0 L/100 km saving around town. I'd save more fuel by just putting supercats back on the car - at least 0.5 L/100 km.

That means I am saving maybe $250 of fuel with 10,000 km of driving. One failed oxygen sensor will eat all of those savings.

 

If it was on a bigger car that used like 15 L/100 km and dropped down to like 11 L/100 km then it would make far more financial sense to keep hunting for more and more efficiency as the cost of the sensors and parts doesn't change.

 

My only motivation to go to ECU controlled ignition is for the fun of it and to potentially fix the power hole between 5100 and 5400 rpm. Even then pretty much everyone reckons you need to get the car dyno tuned if you are doing ECU controlled ignition as you will never get the full potential by just doing it by feel/sound on the road as you won't be able to hold it in each cell for long enough and there is no auto tune function for the ignition. Dyno costs $$$ and therefore the same argument for above can be applied if one was to argue about it in a financial manner.

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You definitely don't need a dyno especially for a low power car. As you can just nang it up the open road and get some good results because you aren't accelerating too fast.

Also it's really easy to find the timing plateau.

Also, it's immensely satisfying and heaps of fun.

In my dyno session I gained nothing over my road tune.

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I'm still planning on having a go at ECU controlled ignition at some point soon, but that video really did drop my expectations of extra power. I guess ignition tuning would really be something suited to having a passenger work on it though so I'll have to recruit a minion / get Jane to do it when I get the car back down to Christchurch.

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