Yeah those look normal enough, I'd get some NGKs which are the OEM plug. Couldn't pay me to put Autolites in anything I own. The NGK plugs for the MSM's are IFR5T-8N.

 

recommendations on wires/coils?

 

Any of the .032" plugs here: https://ngksparkplugs.com/en/part-finder. You can find the wires there too.

 

You sort this out?

 

Thanks to all as I am still learning. Plugs pulled, cleaned, regapped and they were all at .040 to .042. Brought down to .032. COLD compression test done and all within 30 psi if I did it right. #4 was near the highest. Replace it all as it was. Started, error code P304. Next day, swapped the coils 2&4. Started and let warm up w/o touching the gas. Error code P300. Put in the Chevron cleaner, started, let it warm up, no touch the gas, no error codes. started again today, fiddled with gas pedal, error code P304. Clean the IAC or get new plugs/wires/coils? Once again, once warmed up,runs like a champ.

Thanks for all your help

 

continue to get the P304 error code .... I will get new plugs ... where to get the new wires/coils?? Again, once warmed up, runs like a champ. Thanks for all the help

 

You could try putting the 1/4 on 2/3 and vice versa. If your error code changes to cyl 2 or 3 then you'd know it's a coil / plug / wire issue.

 

Abratech, see my thread above, I have done the compression check and all is good, I have removed, cleaned and regapped the plugs, all installed in exact position, I have swapped the coils 2/4 and still getting P0304 but only when cold. Runs great. Not getting any stalling. Any more recommendations .. appreciate you help as I am thinking about taking it in. Thanks.

 

I didn't re-read the entire thread but if you still haven't tried new plugs / wires, that's what I'd do.

 

All new plugs. Starts great and if I do NOT touch the gas until fully warmed up, no error codes. Next day, started and fiddled with gas while cold/warming up and error code. What are you thoughts on a faulty/clogged #4 fuel injector? Best brand to replace it? Do all 4 since is will all be apart? Only 34k miles on these original ones. Thanks.

 

If it’s not a DD just live with it and let it warm up before driving? If you want to do injectors and stay OEM, Treasure Coast Miata sells tested sets for pretty cheap (I’m not affiliated with them and have never bought from them but they have a good reputation).

 

I have to ask. What is a 'DD'?

 

Daily driver.

 

Good news is, MSM and non-MSM 01-05 injectors are the same, so any purple injector set can be purchased, sent out of cleaning, and swapped in. Alternatively, you could send your set out for cleaning, or simply swap out cyl. 4 for another and see if the problem moves. If it only has 30k in 20 years, there's a good chance the engine isn't in great health. If you can, drive it on the freeway at high speeds (5-10mph over the speed limit) for an hour, turn around, do it again. Luckily, this is all you need to for an "Italian tune up" on Miatas, since they're such short gearing. My suspicion is a valve that's not seating well due to build up, or a ring that's a little stuck when cold. These issues won't necessarily show up on a compression test.

 

Curly, why would the engine be in bad shape with only 34K miles on it? Just trying to learn. Thanks for your insight and I will take a long ride tomorrow.

 

Curly will likely give you a more specific answer (because he’s better at this stuff!) but condensation accumulates, seals dry out, etc. when a car just sits for prolonged periods of time.

 

Yeah more or less. Oil collects moisture over time, the way to reduce that moisture is to heat the oil for long periods of time. Your car has done an average of 1600 miles/year, where as the average daily driver does 10,000-15000. Low miles is usually a good thing, but occasionally it's not. Not sure what kind of maintenance you've done to it, for instance due to age, you should technically be on your 3rd timing belt, water pump, valve cover gasket, and related parts.

Do you have a picture of the engine bay you can post here?

 

hope this helps. great guidance from you guys.

 

Ok, so pretty much bone stock with an intake. Wouldn't be a terrible idea to check for vacuum leaks with a smoke machine, I see some misplaced clamps and tape on hoses. You could check the long term and short term trims with whatever tool you're using to read/clear OBD2 codes with to see if there's an air/fuel issue happening. High positive trims means extra is entering somewhere, negative trims indicate an air restriction or fueling issue.

 

Curly .... continue learning and cannot thank you enough. STFT is 0%. LTFT if engine wasn't too cool 1.6%. Seems to be within norms as I have researched. Will take the long drive tomorrow, with the Sea Foam in there and retest when I get home. More to come.