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My car wont start, but the engine turns over fine. I have already replaced my ignition control module.

Tiny
DUSTINHUGHES
  • MEMBER
  • 1990 MAZDA MX5
  • 4,600 MILES
I have a 1990 mazda miata, recently I have had a new motor put in the vehicle. Motor and motor only. The can was driving perfect and suddenly shut off while coasting in fith with the clutch out it would not start, apon stoping the car will crank and the engine turns over fine. I can unplug any plug wire and ground it to the block with a spare spark plug in it, there is no spark. In a haynes manual my coil pack should ohms out between 10.5 - 15.5 both coils 1/4 and 2/3 ohms out at 12.33. I have replaced my ignition control module wich is on my passenger side fender well, my coil pack is on the back driver side of my engine with my crank angle sensor on my back passenger side of the engine. I am at a loss, the only thing I havent replaced is my crank angle sensor, and my ECU
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Tuesday, August 7th, 2012 AT 11:54 PM

10 Replies

Tiny
ASEMASTER6371
  • MECHANIC
  • 52,797 POSTS
It sounds like the timing belt let go but to be sure lets check out this guide.

https://www.2carpros.com/articles/car-cranks-but-wont-start

Roy
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Tuesday, August 7th, 2012 AT 11:56 PM
Tiny
DUSTINHUGHES
  • MEMBER
  • 5 POSTS
I know im getting fuel because I have drove the car and had it shut off on three occassions since this started so compression timing and fuel are not my problems. Thanks Roy
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Wednesday, August 8th, 2012 AT 12:04 AM
Tiny
DUSTINHUGHES
  • MEMBER
  • 5 POSTS
My coils both read at 12.33 ohms and I have replaced the ignition control module on the passenger fender well, but I have no spark at any plug, im getting fuel, compression and timing are ok.
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Wednesday, August 8th, 2012 AT 12:07 AM
Tiny
ASEMASTER6371
  • MECHANIC
  • 52,797 POSTS
One of them has to be as it needs all three to start.

What is the actual fuel pressure?

Roy
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Wednesday, August 8th, 2012 AT 12:55 AM
Tiny
DUSTINHUGHES
  • MEMBER
  • 5 POSTS
No spark on any plug or wire, but both coils ohms out at 12.33, I have changed my ignition control module and still no spark. Engine turns over fine and im getting fuel as it has crank and ran three times since this has started but when it quits it doesnt get any fire to the plug, wires, or coil, and it does not have a distributor
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Wednesday, August 8th, 2012 AT 1:28 AM
Tiny
DUSTINHUGHES
  • MEMBER
  • 5 POSTS
Lol no offense but your obviously not a so called ase certified expert mechanic, because you obviously havn't read the first sentence of anything I told you, im not getting any fire, but its periodically. When I do get fire the car cranks and runs fine, yes im getting fuel yes the car is in timing and duh the camshaft is spinning or else it would crank up and run every so often, my coil packs 1/4 and 2/3 are both fine the ohms out at 12.33, the ignition control module is brand new. Can a camshaft position sensor ever go in and out, and the same with the ecu can I go in and out periodically. Dont mean to be ill but your asking questions iv already answered. PLZ READ
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Wednesday, August 8th, 2012 AT 2:02 PM
Tiny
RIVERMIKERAT
  • MECHANIC
  • 6,110 POSTS
Dustinhughes, yes, actually sensors can go wonky and periodically work and not work. This is usually leading up to a complete failure of the part. They are usually nothing more than a hall effect transistor triggered by a magnet on the rotating part. Every time the magnet passes the transistor sensor, it's supposed to close the circuit. But the silicon-silicon junction of the transistor can be getting ready to fail completely. Using an ANALOG resistance meter, or a NOID light, hook up to the leads from the cam sensor and crank the engine when it won't start. Watch the needle or NOID closely. Then do the same on the crank sensor.

Let me know what you see or don't see.
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Thursday, August 9th, 2012 AT 2:08 AM
Tiny
KHLOW2008
  • MECHANIC
  • 41,815 POSTS
The coil pack has 2 circuits, one is the primary and the other is secondary. The secondary cirsuits are within specs but what about the primary?

Problem indicates a likely fault with the crank position sensor as that is the one responsible for ignition sparks.
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Thursday, August 9th, 2012 AT 12:55 PM
Tiny
RIVERMIKERAT
  • MECHANIC
  • 6,110 POSTS
My thoughts exactly.
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Thursday, August 9th, 2012 AT 2:30 PM
Tiny
JUANLAMAS
  • MEMBER
  • 1 POST
Pay close attention to the crank pulley and crank sensor, make sure the sensor didnt come loose and not picking up signal from pulley, also make sure the wire from ckp sensor is routed correct and is not rubbing on anything that would have damage the wire, in the past I have seen the key way on crank to get worn out and causing it not to start, but u have a new engine so dont think that is the problem.
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Friday, August 17th, 2012 AT 1:14 PM

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