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This is a fascinating series of photos I took of a Mazda RX-7 fuel injector in the process of firing.  The injector was mounted on my fuel injection flow bench and the bench was driven by some custom software on a laptop.  Also connected to the laptop was a General Radio Strobotach.  The Strobotach generates a very brief flash of light when triggered, brief enough to freeze the spray montion.

The way the software works is this.  At a specified firing rate, the software fires the injector and then after a specified delay, fires the strobe.  The delay allows the spray pattern to form.

The entire setup was in a dark room.  The camera shutter was opened, the software operated in single-shot mode to fire one burst and then the shutter closed.  The delay between injector firing and strobe firing was incremented 1 millisecond and the process repeated.  The photos were combined in a photo editing package.

Sorry for the lack of color but these were taken pre-digicam (!) and B&W film was used to get the necessary speed.

This is a Shraeder valve core removal tool.  It is used to remove the valve core from an AC service port prior to evacuating and charging the system.  Removing the valve allows much higher flow into and out of the system.

The clever design of this tool allows the core to be removed, inserted and even replaced while the system is under pressure (or vacuum.)  The core removal rod is simply backed out enough to clear the isolation valve.  The valve is closed, isolating the system.  The compression nut is unscrewed, releasing the rod and core.  If necessary a new core can be fitted and the process reversed.

The tool can also be used to measure the internal temperature of the system.  The core rod is removed and a stem thermometer with the same diameter is inserted.  After the compression nut is tightened, the isolation valve is opened and the thermometer bulb is inserted into the system.  Handy.

Few auto techs seem to be familiar with this tool, which is why I posted it here.  I got mine from Johnstone Supply.  It should be available from most any HVAC supply company.

The kind of problem that will drive you crazy

My Caprice had one of those problems that drives one crazy.  An intermittent electrical problem.  The symptom was that I'd be cruising down the road when the engine would cut out for a fraction of a second.  Just enough to allow the drivetrain slack to jerk.  I spent hours tracing down wiring, cleaning contacts, checking fuse connections and everything else that I could think of.

Then one day the car quit.  When I had to be at an important appointment, of course.  In troubleshooting the problem, I found that I could lift the air box/flow meter and the engine would run.  Lower it and it would stop.  Hmmmm!  More poking around led me to discover that the engine didn't completely stop, it just went way-rich.  If I snatched the throttle open before rotation stopped, the engine would run, albeit, heavily loaded-up.

Suspecting the MAF connector or wiring, I disassembled the intake system.  Nothing looked amiss.  The car started and ran OK with the MAF dummied onto the throttle body.  So I tried the last resort - hard tugging (as opposed to gentle wiggling) on all the wiring harnesses.

When I pulled on one harness, the engine quit rich again.  I still couldn't see anything wrong so I started tugging on individual wires.  When I tugged the last wire in a bundle of ground wires, I saw what you see in photo 1 above.  The friggin' solderless connector had stress-fractured at the junction of the ring and crimp section.  I hate to say it but this is absolutely the cheapest, lowest quality crimp connector that I've ever seen.

These are all grounds associated with the engine management system so undoubtedly this failed ground sent some signal to the rail, causing the full-rich condition.

If you look at photo 2 (sorry for the auto-focus on my finger), you can see that the fatigue fracture took place over time.  Most of the fracture is covered with grease while just a spot on the edge (arrow) is shiny.  That's the last little part that finally fractured.  After the fracture, the wire end remained in contact with the loop most of the time.  Except for those little burps when it didn't.

The problem's fixed now, though I'm a little crazier and have a little less hair than I did before.  I'm posting this as an example of the kinds of things to look for before going on a parts-changing binge.  A less careful mechanic would probably have just changed the MAF and declared it fixed.  Until the connection failed the next time.  I like to find the cause of the problem before I start changing parts.

I should note too, that the PCM never reported a meaningful code.  It just isn't capable of figuring out this kind of problem.  This illustrates the limitation of scan tools.

Update 08/01/08:  I've been told that this isn't the car that Hank died in.  The placard in front of the car said that it was Hank's death car.  Now I need to find out what this car really is.

Update 08/02/08: One of my vintage car expert friends has told me that this is a 1949 Mercury two door, the only year of that exact body style.  How it was connected to Hank awaits a reply back from the muscle car museum.

Update 08/02/08: From the MuscleCar Museum.  The swamp cooler had nothing to do with Hank.  They hung it on the car for nostalga purposes.