I have a 1991 Miata. When I try to start it a whole title to 1300 and then falls on his face after that it doesn’t like to start at all it’ll run but barely and if you give it any throttle a completely cut seven days it could be the engine temp sensor but usually that throws a check engine light which I do not have so any suggestions for the fix anything would be greatly appreciated thank you

 

Assuming nothing previously has been changed, I would check for vacuum air leaks first. That is the most common issue with poor idle and worn hoses. You can try to blow smoke through the air path to find holes, or spray soapy water around areas that might be failing. The soapy water may bubble, or be thick enough to improve idle, sealing minor leaks. That can help you diagnose locations.

Also check the tiny rubber hoses that connect to the engine on the passenger side. They can get old and brittle.

 

Also, a OBD2 reader is very cheap nowadays. It can display pending codes before the CEL appears. You could have problems, but your car hasn’t displayed it yet.

 

Yeah I’ll look for that but do you really think it would also run better when cold I can’t see vacuum lines causing that but I will look it to that and since it’s a 91 there is no obd2 if there was then I wouldn’t be having this issue haha but hey at least I don’t have to pay for emissions

 

Good call, forgot you have OBD1. I don’t think it’ll run better cold. The car just dumps a lot of fuel in just to try and keep it running. You might try starting the car and idling with TEN and GND shorted. Look it up on google. Very easy to follow, but be very careful you’re following for your car model (NA), and using a paper clip to connect the right terminals. (I actually used some paint to mark both holes for future reference). Grounding these, can help you determine problems with basic idling, taking the IAC out of the picture.

 

Ive tried that and no check engine lights come on, and how would you see if the IAC is bad? I don’t know if it’s that but it’s confusing lol. Anyways if you have anymore ideas let me know and I appreciate it!!

 

It's the component under your throttle body inlet. It's held in by 2 phillips head screws.

Take it off and inspect it for grime. If you put the car power on without running, it should prime. You may hear a little humming, but you should see the valve move a tiny bit as well.

I'm not sure if you've been working on the car and something's changed, or if it just slowly started dying on its own. But check the NA section, someone posted a question sort of like yours and it has a few more things to consider. Hope that helps!