Tuners: Test Your Injectors!

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Tuners: Test Your Injectors!
This multi hole injector is a mess.  Any flow vectoring is gone and the holes are full of burrs.  The pintel head is probably dinged as well.  Put this in your engine?  It's cheap!

 

Basically, you will setup the test stand to flow an injector into the bucket on the scale. Acoustically attach (IE. metal to metal) the Bosch Detonation Sensor to the clamp holding the injector above the bucket and connect it to channel #2 of your scope, channel #1 of the scope is connected to the Inductive Current Probe, which is clamped onto the signal wire firing the injector. Setup the power supply with a switch for the pump, one for power to the injector thru the timer for static flow tests and one thru the timer and then thru the Signal Generator / Driver for dynamic flow testing (a pulse counter is also a nice addition to confirm the pulse count). Ok, that said, again, J1832 contains the specifications for accuracy and resolution required for the above mentioned components, so read it before buying anything you don’t already have.

 

Tuners: Test Your Injectors!
The holes are burred and hacked.  The damage to the pintle head is very obvious when looking through the holes.  This is a very well known brand of modded injectors, popular in the Nissan and EVO tuning world.

 

The following is a basic description of the setup and operation of a test rig, plus a few details not in J1832 (yet ;-).  Setup the scope to trigger on the Current Probe on channel #1 and set the display for 1ms per division, the amplitude setting isn’t important, just set it so you can see both channels. Once you have the scope triggering on channel #1, the Det. Sensor on channel #2 will show the injector pintle hitting the full open stop inside the injector on opening and hitting the seat on closing. When setup correctly, channel #2 will show a ringing oscillation when the injector pintle hits full open, with the first upward oscillation of the ringing pattern coinciding with a “knee” in the Current wave form on channel #1.

 

Tuners: Test Your Injectors!
The holes are all different sizes and every single one has smacked the pintle head.  All of these pictures were taken with a microscope which should give you a clue as to how small these holes are.  You cannot drill stuff like this under aftermarket like conditions.  Machining these holes requires special processes that OEM's have access to.

 

The “knee” is a slight deviation in the rising current caused when the pintle movement thru the magnetic field stops. Use these two coinciding events on both channels to confirm everything is correctly displayed, since on the closing side, the fully closed event does not have a coinciding event on channel #1 for confirmation. On the closing side, channel #1 will be a fairly straight vertical dropping line as power is turned off and channel #2 will show another ringing oscillation, typically .5ms to 1ms after power is turned off. The first downward cycle of the oscillation is the pintle hitting the seat, indicating the injector has fully closed.

 

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