8-10-03  /  8 hours  /  1316 total

Wired up the latest tach, and also changed the Tiny Tach pickup wire.  The instructions show the pickup wire being wrapped around a plug wire 3-4 times, with maybe 1/8” between turns.  I tried to outsmart the people who designed it, and wrapped it the full length of the pickup wire (about 7 turns).  I also made a tight coil out of it, rather than leaving a gap between turns.  Results- the new tach does nothing, and the Tiny Tach worked fine at all rpms.  This is good news for me (and John Slade), since I can continue to use the Tiny Tach.  Out of curiosity, I put a very nice digital, color oscilloscope on the LSI trigger wire to see that the pulse looked like.  It’s only about 4 volts, which is probably why the automotive tachs don’t like it.  I would have to bet that the Mazda coils have a higher voltage on the trigger.

With the MAP lines hooked up, the computer seems happier, as does my boost gauge.  I got through a rough tuning of the A controller, but idle and low speed still isn’t smooth, and tends to be rich.  When I advance the throttle to sea level pressure, I have a static rpm of 4900, and plenty of throttle left.  Fully advancing the throttle give 5900 rpm, at 3 psi of boost (33 inches MAP).  This is with a pop-off valve set to 1.5 psi, and the wastegate fully open.  The boost is VERY controllable with the throttle lever, and having the boost gauge on top of the glare shield, in plain view will make this work fine I believe.  3 psi is a good limit for now, and I’ll attempt to keep it at maybe 1 psi to prove that I can control it.  Eventually, I’ll raise the pop-off valve setting, and allow higher boost to be available at altitude. 

Now back to my rough engine problem.  After some troubleshooting with the primary and secondary injector switches, I’ve come to the conclusion that I have a primary injector that’s sticking.  When running on the secondaries alone, the idle is smooth down to about 900 rpm.  Turning on the primaries instantly makes the engine erratic.  You can tell that the overall mixture is rich from the air fuel meter, but leaning the mixture on the EC-2 causes the engine to feel like it’s running on a single rotor.  I’m thinking that one primary injector is leaking, or sticking open to some extent, and leaning the mixture reduces the good injector to the point where that rotor quits firing.  These were used injectors, that I didn’t have tested, cleaned, or inspected, so I have no reason to believe they’re working properly.  I’ll order two new injectors tomorrow, for about $250 each.  As much trouble as they are to replace, I’m going to put in new ones, so there’s no chance of having to do this again.  Once that’s done, I should be able to get back to tuning, and hopefully, it will go quickly.