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Fuel injector test unit with weird circuitry (Patreon)

Published:
2023-03-22 00:35:21
Imported:
2023-03

Content

I'm not sure if there are multiple variants of this unit or if it's just another stolen design with legacy circuitry and software.

The software is terrible.  Really basic, and the only way to change mode is to force a processor reset and start from the beginning.

The dual voltage functionality has me perplexed.  The only thing I can think of is that it may be designed to initially power the injector at 12V then step down to a lower voltage once the solenoid has pulled in, to reduce dissipation.

https://www.youtube.com/watch?v=IyTHihEJX_M

Files

Inside a fuel injector tester (with schematic)

Although this unit is designed for testing fuel injectors, it may have other applications where a 12V load needs tested with very brief pulses of current. One other thing I'd add to my version of the tester is a PTC thermistor fuse. Probably rated for 500mA or less, as the brief pulses should not trip it, but a short circuit or continuous operation due to the processor crashing or transistor failure will cause the current to be limited. In use a fuel injector is fed a pressurised supply of fuel and gates it into the cylinder as a fine mist electrically. Common failures are blocked nozzles resulting in low fuel volume or a coarse spray pattern. The injectors can often be cleaned and fitted with new inlet filters. This unit causes them to fire so that you can either hear them click, or observe the quality of the fuel spray. The full size garage units have the injectors in a chamber so they can be observed operating. If you enjoy these videos you can help support the channel with a dollar for coffee, cookies and random gadgets for disassembly at:- http://www.bigclive.com/coffee.htm This also keeps the channel independent of YouTube's algorithm quirks, allowing it to be a bit more dangerous and naughty. #ElectronicsCreators

Comments

Paul Menghorne

13.8V tends to be a good threshold for determining whether an engine with 12V ignition is on or not (the voltage when running will be 14Vish) as it allows for both strong batteries that will hover over 12V for a while after switch off and weak alternators. That being said, to me it doesn't seem like a good idea to test injectors in place while the fuel pump is running - and would not cater for smarter alternators that drop off once the battery is charged - but perhaps "because China" comes into play.

Andy Brown

The 2 voltages is "Peak and hold" - A higher current pulse opens the valve, a lower current holds it open and allows the magnetic field to partially reduce, so there's a lower residual magnetism when the valve needs to close quickly. It's for magnetic reasons.

bigclive
>>104674071

Darn! I wish I'd read this just before recording the new version of this video with a scoped waveform showing the voltage switching. I'll add that to the description of the new video.