Pusled Fuel Injector Tester using two 555 timers

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Pusled Fuel Injector Tester using two 555 timers

Postby makerdino » January 30th, 2011, 7:40 am

Hi all...
If you're a regular visitor to Hack A Day then you've probably seen this project but it's a work still in progress so I figured I'd share it here.

I spent several hours yesterday reworking the schematic and the next step is to make a PCB, solder up the components to it and get it in a new larger enclosure. I'll probably do another video of the PCB build because I'll be using the Laser printer technique.

The way I use this as a diagnostic tool goes like this. Let's say a car has a "miss" on one cylinder but I'm not sure which one. Let's assume that I've ruled out ignition as the cause and I know it has to do with fuel delivery. I connect a fuel pressure gauge to the fuel rail and connect the injector tester to power. Then I connect the tester output leads to one of the injectors. The fuel pump is turned on momentarily to pressurize the system then turned of. The system is now holding a static pressure and I note the reading on the gauge. Then I trigger the tester which pulses the injector and allow fuel to flow. I note the pressure drop, repeat for the sake of gathering accurate data, then move on to the next injector and repeat the process. If one is delivering a low or high output it will show up as a variance in the pressure drop.

I have added a switch that will allow selection of different output times. 1 second, 2 seconds or continuous by holding down the trigger switch. This is useful for visually testing the injector spray pattern or volume of fuel delivered over time.

Since I use two 555 timers in this, I plan on entering it in the 555 contest:

I have a video on Youtube which explains a lot of what his project is about:

You can also visit the project page on my website:

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Joined: January 27th, 2011, 5:27 pm

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