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DIY Fuel injection thread.


yoeddynz

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Definitely, need to keep in mind that you are measuring average of several cylinders and also that even in a single cylinder you arent necessarily getting uniform combustion.

You are measuring an average of averages with a laggy and non perfect sensor.

 

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And yes also keep in mind that when you run leaner it combusts a lot slower, so you need more timing for the same amount of air and fuel. 

A while back when I tried running some leaner cruising conditions, I found I needed 9 degrees more timing in some areas.

Which reminds me I need to stop pissing around and finish off my Ignition trim computer haha.

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Yeah not too sure. 

I've been looking at some waveforms of the ion sensing return signals on Toyota 4 pin coilpacks a while back, and I think I've seen what looks like  evidence of a "second shot" if theres a partial fire or misfire. 

I've got some blownup coilpacks somewhere so I've been meaning to chop the tops off and see how sophisticated the ciruit is (or isnt)

I do remember that there is a circuit board inside the cooling fluid on top of the coil though. 

Just about any modern coil on plug seems to all made by Delphi who have the later versions which do the repeat fire thing. 

2005ish era Toyota coilpacks are definitely only a single fire if there's confirmation from ion sensing that it's fired correctly.

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Coils without a ion / primary pin piss me off. So much info can be gathered from the spark ionization, can see if the cylinder is rich or lean or leaking valve and all sorts. VW coils are the worst as they are also shielded, so can't even pick up the spark via induction.

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Common practice for any aftermarket ECU install is "Fuck those return pins"

But yeah after looking into it, such a waste! Could tell so much if ECU was configured for it.

"Hey, when engine gets hot coilpack number 3 starts to misfire 6000rpm onwards"

instead of 

"......"

And the knock sensing capabilities are just mind blowing. Strapping a mic to the side of the engine is so ghetto by comparison hahaha.

At some point I want to see if I can get anything meaningful with a Teensy 3.6 by doing a burst reading just after ignition on the return pin. Then analyzing the waveform for however long that takes. (Doesnt need to read every single event)

It should have enough speed to capture at least 1 degree of crank movement at 4k+ rpm.

Will get there eventually...
 

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1 hour ago, ajg193 said:

What's the go with those MSD multispark box things? Would they allow you to run even leaner as the multiple sparks are more likely to ignite the fuel (they claim to make a 20 degree spark duration or some shit)

I dunno about running leaner but those multispark boxes are the business. Cold starts are a piece of piss and it'll go straight into a smooth idle. Only wish they did a hard ignition cut though :)

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See the chicken scratchings below.

I am about to put some injectors into some carbs but have a query about placement. 

Top drawing shows the fuel spraying on the throttle plate and as it opens it gets well smashed on the plate for good mixing, but ends up mostly going over the top above 50% throttle

Lower one is stock throttle plate.

I think at idle it will pool at the bottom of the plate?

67087819_2018-08-3123_20_44.jpg.443cb81f3afef664220d4a1067d63499.jpg

The injector location is my only option unless i can find the injectors i saw once that have a lottle 45degree deflector thingy on the end of them to allow me to mount them vertical. 

 

It appears to be easy to flip the plates so no issues with changing it.

 

Any ideas welcomed

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it will still work.. But economy and idle/ cruise might not be as clean as you want. 

Id put them in the manifold behind the valve if at all possible. 

a lot of things at play other than throttle plate. 

injector spray pattern helps a lot with the low rpm stuff. Up top does not seam to make a difference even if your injectors look like water pistols. 

How far are the carbs from the head ? Less of a issue if it's a short runner. 

 

 

 

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Just now, scooters said:

it will still work.. But economy and idle/ cruise might not be as clean as you want. 

Id put them in the manifold behind the valve if at all possible. 

a lot of things at play other than throttle plate. 

injector spray pattern helps a lot with the low rpm stuff. Up top does not seam to make a difference even if your injectors look like water pistols. 

How far are the carbs from the head ? Less of a issue if it's a short runner. 

 

 

 

@fletch

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Anywhere that has potential to pool fuel is total poison to tune. I had an encounter with a supercharged pinto which was injected pre supercharger.

Could tune it fine on song and at idle but the transition off idle when it gulped the pooling fuel was a disaster and the idea eventually was scrapped. 

Get those injectors as close to the head as possible...

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On 29/08/2018 at 23:39, Roman said:

Today I setup a TPS a based idle fuel map, thats only active below 5% throttle and 1300rpm.

This is a cool thing!  I was always chasing a smoother idle on the V6.  I will try this next time although not sure if tuner studio allows it? Anyone? Bueller? Bueller? Bueller?

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