Adjusting The Mazda Miata's "No-Touch" Screw, Setting Base Idle and Timing, and MORE! 

Good point! I forgot to mention this!

@@bbishoppcm For the rest, a very good detailed video. Some owner before me touched the screw and I couldn't find a way to fix it till now. You did some good research.

What seems to be the bigger issue is if the stop screw is too far out of adjustment, you'll NEVER get the throttle position sensor adjusted properly.

Good to know! The instructions were pretty weak, and I was unable to find this setting.

I believe I got those measurements from the Haynes manual in regards to throttle position sensor…

@@bbishoppcm cheers

My car is as close to "as it left the factory" as it gets - it's possible that these changes (additional ground wire) were made in the 1994 refresh when they completely overhauled the induction system and switched from the vane and potentiometer airflow meter to the solid-state type used in 1994+ model years. Since I reset the base idle, the car still acted up occasionally - it wasn't until I replaced the coolant temperature sensor that it 100% solved all issues. I would explore a bit further before any modifications if it were me - the 1994+ DOES have an idle air control valve - it's a different design and is located UNDER the throttle body. Removing this valve WILL cause issues (the engine will no longer be able to compensate for cold starting, accessory load, and other variables that affect idle speed) - when I was a kid, I basically did this to my 1987 VW GTI and it never ran right since. The IAC valves regularly fail and replacement parts from (insert online or physical part store here) are usually utter garbage - try finding a good used one from a wrecked low-mileage car before bypassing it entirely.

No idea

No; I used a strobe w/ built-in tach

I believe this is it; askatech.com/AskATechLive/AatFileShare/References/FastTrack/MA007.pdf

Try this procedure instead! Save money!

the hell's that supposed to mean?

@@bbishoppcm Years ago, the view counter on recently uploaded RU-vid videos would get stuck on 301 views for quite a while before starting to increase again.

It also sets the stop point for the throttle plate, the position of which needs to correlate to the “idle” position on the throttle position sensor - basically, a starting point for adjusting everything else

I know they used the same engine in the GT as the Miata, not sure if its the same fuel system and intake though

It’s OBD-1, it would have had to fail catastrophically for this to occur

It takes quite a bit to trip-up OBD-I; minor value drift doesn’t seem to affect it, but a totally open or closed circuit may.

You can see the ohm reading in graph form and you will see abnormal jump in numbers as the temperature increases.. Just like the TPS sensor, a sudden jump in voltage as you advance the throttle plate slowly.

@@vincentlee2460 You are correct- on an OBD-II car, a good scan tool will give you a graph reading of the sensor's output and any sudden jumps in resistance will indicate a "soft failure" of the part (value drift). The onboard diagnostics on PRE-OBD II cars is VERY primitive - it will only trigger an error code (in the form of blinking lights while in diagnostic mode) IF the sensor goes open-circuit or shorts out internally. The only way to properly test this sensor is to remove it, place it in a pot of boiling water, and measure the resistance. In the 90s, the dealers may have had access to a more thorough diagnostic system, but these systems are loooong gone. I figure, if I have to drain down the cooling system and go through the trouble of removing it to test it, I'd might as well spend the $40 on a new one and move on. I hope this clarifies my situation. Since I replaced the sensor and recalibrated the throttle body, I've had ZERO issues and it's been over a year.

Thinking about your comment, you could place it in a pot on the stove and connect it in-line with a regulated power source (5v?) and add a multimeter in-line, then turn the burner on and watch the resistance go up (or down?), watching for any sudden jumps in the readout. Or use an oscilloscope that records... but again, I'd still need to remove it from the back of the cylinder head which is a total pain in the ass... the OEM sensor was only $40 so I just swapped it.

*Ramblings

I enjoyed the “ramplings”.

Huh?

It's not his it belongs to the bad cat 😉

so what bro, mind yo fuckin business

Not sure what you found confusing - there is a lot of information to cover here, and no matter how I preset it I will be criticized for it. If you have any specific questions, I’d be happy to answer them here.

Yes