Mazda Repair: 90 miata mx 5 timing, crank angle sensor, crankshaft pulley

Question
I'm trying to fix a very low power situation at takeoff. I do not know how to hookup my timing light to the 1.6 liter engine. The battery is in the trunk, so I would like to know where else in the engine compartment I can connect the power lead. I would like to check the timing first, then go into the mass air flow system. I have new plugs, wires, pcv, etc. It ran fine for awhile, after I paid a mechanic to "fix" it, but 2 month's later, it is doing it again. I want to do it myself now.  Thanks, Wes

Answer
On the driver's side behind the headlamp assembly is a blue service power port on the wire harness.  It usually has a blue insert to cover the male spade within.  This is in place to allow technicians a ready 12 volt switched source contact.

Since it is a 1990 model you must be warned of the worst case scenario. A  common failure has been at the crankshaft keyway, movement here results initially in retarded timing and results in poor acceleration.  A common override has been to over advance the crank angle sensor this is however not a fix rather a masking of the issue.  Timing retard and increase in power continue until eventual crankshaft failure.

Inspect the crankshaft pulley and bolt area for any signs of powdered rust or rubbing of the timing covers and see if the pulley rotates true or if a slight wobble is present.  If the latter is visible your in the early stages of crankshaft/keyway failure.  I would suggest an immediate tear down of the area to inspect the keyway, the crankshaft slot and the boss pulley for abnormalities.

Issues with the mass airflow sensor does not normally result in power loss.

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