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Electronic Diesel Injectors

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Sceadwian

Banned
Dc pulses, no idea other than that. You'd have to test the electrical connections on a working engine. Though someone in the forums here might know more.
 

imix500

Member
Cam operated mechanical injectors are also still in use on some modern Diesels.
Otherwise PWM driven electrical injectors.
 
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BrownOut

Banned
Do you want to test the actual injector, or the trigger? Depending on the current of the trigger pulse, you might be able to ravage an old clamp on ammeter, and just use the clamp as a scope input. I've often thought about trying this; just never got around to it.
 

Mickster

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Most Helpful Member
Roger,
a quick tidbit for Z19DTH (FIAT / GM) Bosch injector is all I can offer right now...

Coil winding - 0.255Ω +/- 0.04Ω
Pressure in injector, via accumulator - 1600 Bar
Peak current - 17A
Hold current - 11A

Peak current is applied briefly to open pintle, then hold current is applied to, erm, hold.....ECM can inject up to 5 times/stroke with a max timing of around 1ms. Pilot injection is around 1mm³.

I can't be 100% sure until I get a chance to check, but I think Pin 1 is positive source and Pin 2 is pulled low by ECM..

Not 100% sure of source V either, but 80V Peak & 50V Hold ring a bell from somewhere...need to check when I get chance.

Hope that gives you a bit of a start.
 

shortbus=

Well-Known Member
Most Helpful Member
Hi, you could build this; RMCybernetics - DIY Homemade Power Pulse Controller to control the pulses on the injector. The injector would go where the load is. This circuit would allow to adjust frequency and pulse width.

Then you would have to come up with a pump and single rail to supply the fluid. I wouldn't use diesel because of the fire risk. Maybe ATF? About the same viscosity.

Cary
 

Sceadwian

Banned
Isn't diesel very difficult to ignite?
 

tcmtech

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Once any combustible liquid is sprayed out of a diesel engine fuel injector at a high pressure its about as combustible as gasoline vapors! :eek:

I have a small single cylinder diesel engine that runs rather well on 100% used motor oil. Although its hard to start when cold without thinning out the oil with E85 first. I have also ran it on a number of other non conventional fuels as well.

Most diesel engines are not that fussy about what they burn. Its rather the injector pump system that doesn't like the thicker fluids, not the engine itself.

Anyone who has an older diesel vehicle or tractor with an all mechanical fuel injection system will find that the engine preforms rather well on a 70/30 mix of used oil and ethanol or E85! If filtered and mixed properly the engines start and run just like they do on regular diesel fuel too!

So If your spraying high pressure even slightly combustible liquids out of an injector treat it just like its gasoline!:)
 

Sceadwian

Banned
I guess atomized fuel/air mixtures are a little different =>
 

crutschow

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Once any combustible liquid is sprayed out of a diesel engine fuel injector at a high pressure its about as combustible as gasoline vapors!
Diesel fuel certainly is combustable when sprayed from an injector, but not a much as gasoline. Gasoline vapor can be readily ignited with a spark, but not diesel fuel or oil. It takes the high compression pressure (and consequent high combustion chamber heat) of a diesel engine to ignite diesel fuel. Thus even if a gasoline engine had a high pressure, diesel type injector it would not be able to readily ignite diesel fuel with a spark plug. That's why you never see a spark ignition engine running on diesel fuel.

Edit: There actually was a spark ignition engine that ran on heavy fuel (Hesselman engine - Wikipedia, the free encyclopedia) but it had to be started on gasoline until it reached operating temperature to allow proper vaporization and ignition of the heavy fuel. It then had to be switched back to gasoline before it was stopped to clear the heavy fuel from the fuel system for the next cold start.
 
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tcmtech

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Not to be the devils advocate but I and several friends have a number of antique engines and farm machines that run on anything from gasoline to kerosene and ordinary diesel fuel.

Two of mine are old GE 32 DC/120AC gen-sets from the 1920's and 30's and I have ran both of them on diesel fuel for extended periods before without problems. They have about 4:1 compression and a sort of glow coil in the intake to help get them started on the thicker low vapor fuels.

My old crawler tractor has the multi fuel carburetor and manifold system on it and is rated to run on kerosene or diesel fuel as well. It doesn't have the glow coil in the intake but it does have a duel fuel feed system for starting on gasoline in order to warm the manifolds up first. Once its warmed up there is a flapper in the intake that reroutes most of the intake A/F mixture into a passage that runs right through center of the exhaust side of the manifold to preheat the A/F mix so the spark ignition will ignite it properly.
 

crutschow

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So the point would be, is that diesel fuel can't be readily ignited by a spark when it is cold, but can be when the fuel is hot, as when the engine is hot or has a glow plug to help heat the fuel. Apparently the cost and complexity of achieving this makes it impractical for modern engines.
 

tcmtech

Banned
Most Helpful Member
Actually diesel fuel mist will ignite with a spark at room temperature.
The old (and still often used) fuel oil furnaces are routinely set up to run on diesel fuel and they are spraying room temp diesel fuel across a spark gap that easily ignites it. Many of the more modern oil furnaces shut off the spark gap a few seconds after the fuel is ignited and the fine spray holds a self sustaining flame. ;)
By adding an air source (bubble atomization principle) to the fuel spray coming out of the nozzle thicker fluids like used motor oil will in fact ignite quite easily and can also still hold a self sustaining flame as well. Used oil burner systems typically work this way.

Its why I still suggest the added precautions with any atomized fuel mists. They may not flash ignite as easily as gasoline vapor but still they can ignite rather easily with far less ignition source energy than most think. ;)
Either way you get a big hot flash thats at minimum rather surprising for a result. :eek:

If the OP manages to fire a fuel injector with 1600 Bars pressure on it there will be an incredibly fine mist produced that will ignite very easily. ;)
 

crutschow

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Actually diesel fuel mist will ignite with a spark at room temperature.
The old (and still often used) fuel oil furnaces are routinely set up to run on diesel fuel and they are spraying room temp diesel fuel across a spark gap that easily ignites it. Many of the more modern oil furnaces shut off the spark gap a few seconds after the fuel is ignited and the fine spray holds a self sustaining flame. ;)
By adding an air source (bubble atomization principle) to the fuel spray coming out of the nozzle thicker fluids like used motor oil will in fact ignite quite easily and can also still hold a self sustaining flame as well. Used oil burner systems typically work this way.

Its why I still suggest the added precautions with any atomized fuel mists. They may not flash ignite as easily as gasoline vapor but still they can ignite rather easily with far less ignition source energy than most think. ;)
Either way you get a big hot flash thats at minimum rather surprising for a result. :eek:

If the OP manages to fire a fuel injector with 1600 Bars pressure on it there will be an incredibly fine mist produced that will ignite very easily. ;)
You make a good point. Certainly I didn't mean to say that atomized diesel fuel won't ignite, just that it didn't seem to ignite very well at room temperature in a spark-ignited, internal combustion engine.

I would guess the problem with engine spark ignition is the limited duration and power of the spark. If there were multiple sparks at a higher energy then the fuel would ignite at room temperature. One of the modern day concerns of such a scheme would probably be smoke and a high exhaust hydrocarbon output from such an engine.
 

DirtyLude

Well-Known Member
Based on the data from Mickster, you should use a proper peak and hold injector circuit rather than simple PWM. I've used the LM1949N for Peak and Hold gasoline injectors and the operation should be the same for the diesel injectors. Check the datasheet.

A Google search for LM1949 will give several sample circuits and test setups.
 
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rogsilk

New Member
After a bit of research i find injectors open three times during their cycle,first a small amount is injected, this is to start the ignition sequence and also to cut the diesel knock,the second is the main injection when the main fuel is injected, and the last one is to help the burn complete.
So this means that i need a circuit to fire the injector three times within twenty 20 deg,all different amounts.
Ive had a look at the LM1949 circuit and i dont see why i cant use it.
Have taken readings from injectors ive got and get a reading of 0.5ohms on the coils, all 12volt
What do you think?
roger.
sorry about spelling, should have gone to school.
 
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