Engine stalled; rotates but didn't start; started again

[vincevince]

Car is NA6. no a/c or p/s.
I was going through a hungry jacks drivethru, stopped behind another car, and all of a sudden - Stall / Cut out.
Tried to restart 5 times, but it would only rotate as if I were doing an compression test.

Embarrassingly, I pushed it into the waiting bay with the help of an HJ's employee.

Give or take 2-3 minutes, the car restarted when I turned the key.

I've searched through this forum and several others, and have found queries on "engine stalling when cold", "stalls when warmed up/hot" --- solutions to them were to fix idle and the drooping, vacuum leaks, fuel pump/filter, crank angle sensor, leads,sparks (checked: good condition), and o2 sensor.

However, none of the threads' OPs had seen them start the car up momentarily after. There was only 1 case of a bloke starting it up 30minutes after warming up the car.

Could it possibly be temp sensor/sender?

Just wanted to double check if anyone has ever had this happen to them on a semi-hot day (>27*C) before I start buying parts and then fixing stuff that doesn't need to be.

Note: I've adjusted the idle according to the "fix your idle droop" guide and it only droops once after giving it throttle now rather than 3-4 times.
I've also disconnected the battery for a day to install new horns and fix my horn button.
I've also cleaned and re-oiled the pod filter (mania intake) as it was clogged with leaves and random tree-like stuff.

Could it just be the ecu "re-learning"?

I'll give it a spin tomorrow morning just so I don't block traffic if it happens again

[NitroDann]

It will be cam angle sensor or something similar, unlikely to be coil packs and wont be any enrichment sensors like AIT or CLT.

Dann

[speed freak]

x2 for cam angle sensor

[vincevince]

Thanks dann and speedfreak.

However, after today's experience with her, I'm now more paranoid that it could be more than just a cam angle sensor.

Today's events;
I started her up in the morning to move into a more shady spot which also happened to be an incline. Tried to start after 10-15 minutes or so but wouldn't fire up.

Thinking it might be the incline's fault + fuel pump issues. I rolled it into a flat spot (which is now a sunny spot). However, even after 2 hours, she still wouldn't fire up.

Fuel gauge needle is just below half way.

- Not sure if any of today's events would change the problem.

How does one test for a faulty cam angle sensor? Or just don't bother?

I have 3 brands at supercheap that I can get for the "engine crank angle sensor": RAE SCO31, Tridon TCAS25 and Premier Auto Trade (PAT) CAS-023.
Tridon being the most pricey. They're all nearly identical just looking at preview images.

[speed freak]

could also be the crank angle sensor. It could be faulty/dirty or may have even come loose.

I would start by checking to see if there are any loose wires/plugs and check those 2 sensors, I know for my NB both of those sensors weren't too expensive (I got mine from MX5 Mania) otherwise I would look at replacing those.

I thought cam angle sensor first because the car was hot/at operating temp and I know (from also being a Subaru fanatic) that when the sensor gets old it can be affected by heat and it makes it do all sorts of weird things, usually is if you try to restart it soon after while the car is still hot/op temp it will only crank over and not fire.

A good way to test that is to pour some cold/cool water over the sensor to cool it down then try to start, if that's the problem it should fire up.

When you firstly started it this morning to move into the shade was it from a dead cold start or had it been dríven before you went to move it?

[vincevince]

@speedfreak, I started it at about 11am - barely a cold morning - but yes, cold start. And no, not dríven for more than 30 seconds just to get up a small incline.
The whole car + engine bay has cooled by now. Checked wires and plugs. No start.
However, I did find some oil dripping at the base of the sensor. Just a bad O-ring?

All the brands have a part that looks like this:
http://www.eziautoparts.com.au/tridon-c ... cas25.html
And it goes inside the distributor.
and like... NAs dont have distributors.. so wtf is tridon on about "located inside distributor"?

[speed freak]

None of the mx5's have a distributor, they run coil packs.

That thing in the picture/link goes inside the cam position sensor which is on the back (closest to the firewall) left (driver) side of the engine, so on the left camshaft on back of engine.

Then you should also have a crank angle sensor which is down near the bottom pully off to the right hand side. That's if its the same as the nb's.

Have you tried starting it again today? Have you tried clutch starting it? Im not 100% sure but it could also be an issue with the air flow meter, the big square box type thing near the air box. There might be fuel going in but no air so its not firing?

Maybe just get some contact cleaner and clean all plugs and sensors first see if that helps.

Just so you know Im not a mechanic and I don't try to be one just going off personal experience, knowledge and research, hopefully I can help somehow so you can go and enjoy your mx again

[speed freak]

I think you actually might be right with the one in that link.

Iv been doing some more research and that sensor on the NA is actually the crank position sensor, it reads the position of the cam then it can determine the position of the crank too, so it must do both jobs, cam and crank angle sensor.

Also that dripping oil you found would just be worn out o rings in the sensor.

I just re-read you last post too about checking the wires and trying to start it again.

http://www.miata.net/garage/cas_seal.html

That link is about changing the seals/o rings but that black plug looks similar to the one in your link so maybe you can disassemble the sensor and replace the plug?

Theres no check engine light on?

[speed freak]

http://www.mx5parts.co.uk/camshaft-angl ... p-852.html

that's the cam angle sensor for the na6

[Martinez]

This does seem to be a reasonably common problem. Has happened to me a few times until I managed to track it down to a loose AFM (airflow measurement) connector.

Try to find the problem first. See if you can read the error codes from the diagnostics port. That might give you clues on faulty sensors. Also check for any loose connectors and burnt fuses. You might have a faulty sensors or something else, but start by looking at the obvious things first

[vincevince]

Thanks again for the help speedfreak

Just before it got dark, I decided I'd do the minimal check on the fuel pump. I followed the haynes manual which tells me to:
1. place a jumper between gnd and f/p on the diagnostic box.
2. remove fuel filler cap.
3. turn car to "on" position but don't spark it.
4. fuel pump sound should be heard from the opened fuel cap and at the parcel shelf. - if no sound is heard, remove and test with 12v (didn't get around to removing it).

But just because I cant hear it doesn't necessarily mean it's stuffed yeah?
In the morning I'll be taking the pump out and testing it with 12v. Can I just run 2 wires from the battery to pump unit to test it out? Or could that risk destroying the pump itself?

Argh. I'll also be going through the "msm engine wont start pdf" and checking for error codes like you said martinez..

Sighface for me.

[sailaholic]

I dont know how much the MSM wont start pdf will help you as the engines had different sensors and different computers.

It's correct the NA6 had no separate crank sensor, it's built into the cam sensor which is actually a misubishi evo unit from the (mazda) factory, the 323 that ran the b6 and BP engines had electronic distributors but these wouldn't fit in the MX5 with the engine rotated north south.

You shouldn't need to pull the pump out, just feed it 12 volts from the battery (positive to the pump, and earth the negative side) and see if you can hear it.

Checking the MAF plug and wires is a really good idea as the ECU turns the fuel pump OFF it it sees no airflow. There will be a guide somewhere that will tell you which pins you can put a paperclip in to test this. They should help you test if it's creating a fuel cut. However the engine probably wont run like this as it will be getting incorrect / no airflow reading from the sensor which it uses to calculate fuel input.

[93_Clubman]

When it won't start you need to identify what's not present, ie 'fuel' &/ or 'spark', given it should be getting 'air' as it runs intermittently:
viewtopic.php?f=29&t=59479&p=748981#p748981

Also, if you end up removing the fuel pump to check/ replace it, you should also check the in-tank wiring & connectors as per:
viewtopic.php?f=55&t=46425

[vincevince]

Today's progress;

1. Tried to crank it, no luck.
2. Disconnected battery to reset ECU.

3. Took off all air ducts to see the condition of the throttle body and gain access to the AFM. Throttle body still has that thin clear coating and not a speck of dirt. The AFM's plate/vane effortlessly with a slight touch..

4. Jumped into the back half of the "MSM engine wont start guide" and checked the fuel injector fuse (all good). Proceeded with the MSM guide to look under the driver's footwell and look for the fuel pump relay (couldn't find it and couldn't hear it click when the ignition was "on" ... wrong side to look under?).

5. Skipped and re-ran the diagnostic for the fuel pump by jumping GND and F/P. Today it was whiring loud and clear. Therefore, not a faulty fuel pump.

6.Checked the EFI relay; checked for continuity and you can definitely hear it click with 12v applied.

7. Couldn't check for spark as I didn't have a helper
8. Inspected spark plugs. They all look in good shape - just the normal use look.

9. Tried to crank. No luck.

10. Fiddled with the underhood fuse box and tucked it back into it's original spot (wiring was tucked and thus fuse box isn't on original mounting)

11. Voila! . Cranks, fires, brum bruuum.

12. Whilst it was running, I thought that maybe it's the fuse box and the wiring being loose. - Moved the fuse box around by twisting it a bit, pushing it down, pinching the wires under it, pulled it up, etc.
Initially, when I put it up against the corner of the firewall and fender, the engine would begin to stall and splutter. Eventually it died. Tried to crank, but no fire.

13. Tilted the box over at a bit of an angle. Crank, START!

14. Played around with it again tugging lightly on the wires under it, but it just didn't seem to replicate that the same effect as putting the box in the corner.

15. Shoved the box back in the corner. Followed by splutter, splutter, die.

16. Repeated #13. And tugged on the wires a little harder. No cut-out.

17. Turned key off. Removed the plug under the relay in the box and blew air at it like an N64 casette. Re-connected it. Shoved in the corner. Cranks, and STARTS!

So far so good. Haven't taken it for a spin yet. Scared it'll die in lots of traffic.

Now it's an electrical loom issue rather than an engine problem?? Aww man, looms are the worst part

[bigdog]

If you had mentioned that the wiring was non standard we would all have pointed you in that direction to start with. One of the overarching principles in looking for a fault is to first check anything you have altered or messed with. Then you go to the standard check list and work through it.

Glad you have found the problem.