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Drew, Super Mazda Tech.
Category: Mazda
Satisfied Customers: 2188
Experience:  19 yrs. experience. Mazda Senior Certified Tech, with Ford, Linc. & Merc. experience. ASE L1 Advanced Certified Master Tech.
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I have a 1991 Mazda Miata with 1.6 Liter engine and 5 speed

Customer Question

I have a 1991 Mazda Miata with 1.6 Liter engine and 5 speed manual transmission. The first start-up of the day is just fine. The non start occurs after driving and shutting off to shop, errands, etc. The no start primarily happens in the Summer when the outside tempertures are 80 degrees and up. The engine cranks over but no start. Usually after waiting 15-30 minutes it will usually start-up if not to HOT out. I am using a Haynes Manual for test procedures and specifications. A multi volt/ohm meter. Parts replaced thus far include: Throttle position sensor, Cam sensor, and Oxygen sensor. The replacement Oxygen sensor help the car run the month of July without any starting problems. Now the no start is reappeared. The air flow/air temp sensors are testing OK. I am running out of ideas to test, hopefully not the power control module.
Submitted: 2 months ago.
Category: Mazda
Expert:  david craig replied 2 months ago.

Hi Im David, sounds like textbook crank position sensor thermal breakdown

Customer: replied 2 months ago.
David-The Service Manual mentions the crankshaft sensor started in 1996. my Miata is a 1991 and has a cam position sensor that I replaced this year, this made not difference in starting. For the month of July I thought the "Hot no start" was resolved when I replaced the Oxygen sensor, but recently the Hot no starting has returned. I rechecked the oxygen sensor output which specs call for below .4 when cold and .5-1.0volts at operating temp. My present reading stay at .4 or below either hot or cold engine temp. Not sure if I am missing something or oxygen sensor gone bad or my test? Any ideas on the power control module since not test for this in manual or other possibilities?
Dan Ishida
Expert:  david craig replied 2 months ago.

the crankshast position sensor is absolutely a part of your vehicle. it inside of the distributor.

Expert:  david craig replied 2 months ago.

that must be a combination crank/cam sensor. it shows both on the distributor but different part numbers??? let me look into this

Expert:  david craig replied 2 months ago.

Part Number: PC217

Brand: Standard Motor Products

Notes: Engine Crankshaft Position Sensor -- Genuine Intermotor Quality

Expert:  david craig replied 2 months ago.

they are also calling it a reference sensor. which makes sense as it reads cam and crank positions...........

Expert:  david craig replied 2 months ago.

try removing and cleaning the idle air control valve. those things get gunked up with carbon big time.

Expert:  david craig replied 2 months ago.

any luck?

Expert:  david craig replied 2 months ago.


Customer: replied 1 month ago.
David- from one of your last response, Could you explain how cleaning the Air idle control effects the HOT NO START? I thought the purpose of the idle control was to raise and lower/return the idle rpm setting, depending upon need such as: A/C turned on, or is their another benefit for the Air Idle control? The cam sensor was been replaced about 3 months ago and no change in the NO-Hot -starting.
Expert:  david craig replied 1 month ago.

if the idle air control motor is stuck open it will affect the vehicle no matter what its doing hot or cold

Customer: replied 1 month ago.
What are other options of when the Engine is HOT and shut off..... Then it does not start-up, but just cranks over and waiting 15-30 minutes will generally start after this wait time?
Expert:  david craig replied 1 month ago.

believe it or not the ignition switch has caused this problem on some vehicles.

Expert:  david craig replied 1 month ago.

the coil pack also is subjected to thermal breakdown on these

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