Miata Ignition Timing - Photos

CAS Location on a 1.8 (Click here for 1.6 view)
On the 1.8 liter engine, look for the cam position sensor behind the left valve cover, near the oil dipstick. Then look directly down the top of the sensor for the long brass colored 12 mm hold down bolt. This bolt does not adjust the timing! It holds the sensor. You have to loosen the bolt and rotate the sensor. Be kind to this bolt. It will break if you overtorque it!
Connecting the Timing Light
	Most owners power their timing light using the blue power connector just behind the driver's side headlight.
Setting the Diagnostic Jumper
Behind the left headlight is a blue plug where you can get 12 volts for your timing light. Before you can check the timing, a jumper must be set in the diagnostic module, which is on the left fender well. The jumper goes between the terminals marked TEN and GRD. Be careful, as the +12 volt terminal is right next to the TEN. Ground the +12V terminal and there will be smoke and maybe a fire burning up your car. Also make sure the engine idle speed is per the shop specifications. I thought the dashboard tachometer was accurate enough for my needs.
	Can't get a wrench onto the hold down bolt? Buy a new wrench. Sears sells a very narrow 3/8 inch flex head ratchet wrench that will fit. Or find a 12 mm box end wrench that has no angle. Not knowing that, I took off the two bolts that hold down the vacuum brake lines that sit above the sensor. This gave me more room to insert a wrench.
	This shows a 12 mm wrench on the hold down bolt. The vacuum lines have been moved. The connector to the sensor was also removed, but must be put back on to run the engine. You can see that a shorter wrench would work better. I marked the position of the sensor before I moved it, to allow it to be reset to the original position if needed.
	Which timing mark to use? Unlike the 1.6 liter cars which have only one mark, my 1994 1.8 engine has a yellow and a white mark. I used the yellow one, and believe that to be correct. It should be around 8 or 10 degrees when you start. Each timing mark represents 2 degrees. The mark on the far right is a "T", and not a "+". Move the marks away from the "T" to advance the timing.

Disclaimers:

Personal Safety. Don't get hurt! You have to be very careful when working on engines, especially when they are running. You don't want your clothing, hair, fingers, electric cords and tools getting caught in the moving parts. Automotive maintenance must be done with an understanding of basic safety rules and the risks involved.

Risks to Engine. If the timing is advanced too far, preignition or pinging will result and this can damage the engine if allowed to occur continuously. From my own experience, pinging rarely happened on my car, except for a few times when it was in the mid 90's outside and I was in stop-and-go traffic. I switched to a higher octane and didn't notice any more problems. However, different cars behave differently, depending on the conditions inside the engine. Another way to stop pinging is to put on a cold air intake.

Where else can you go wrong? A common mistake is to turn the sensor the wrong way and retard the timing. Also, because the hold down bolt is in an unnatural position, be sure you turn it in the proper direction to loosen it It can break off if you overtighten it! I've read about this happening to people. I also heard about someone who thought the hold down bolt adjusted the timing. He kept on turning it until it broke off. Don't do this, because the engine has to be lifted to repair the bolt.

So was it worth it?

Disclaimer:

I'm neither a certifed auto mechanic nor a trained Mazda technician. The information on this page is my own interpretation and may be flat-ass wrong. Use at your own discretion