Mk2.5 won't start. Cranks but won't fire up

Technical Area Engine & Transmission
#1
  1. My model of MX-5 is: Mk2.5 Sport 2003 1.8
  2. I’m based near: Oxford
  3. I’m looking for technical help or recommendations on: why my car won’t start today

I got my car ready yesterday for it going for its MOT today. Its got a problem (P0102 on the OBD reader) where its running rich, but it starts every time. Until this morning!

It turns and turns over but just won’t fire up. (I have a video if anyone is able to let me send it them to upload here.)

Does anyone have any ideas please?

Coil packs?
Cambelt?
I’m stuck for ideas or where to go from here for help.

Thanks!

Darren.

#2

Basics are spark, fuel, compression and timing.
If you get a spark, fuel and compression all at the right time, it will fire.
You need to find out which is missing and go from there.
Does it smell of fuel when it cranks?
If you take a plug out and lay it on the head or other earth, does it spark??

#3

Thank you.

Will the spark plug come out easily, does it twist or unscrew?

If I go and try when it’s dark I should see easily if there’s a spark or not. Do I just need to ensure the plug is touching the top of the engine to be able to check for a spark on each plug?

#4

The body of the plug needs to be earthed
The plugs unscrew lefty loosey.
You need to remove the lead to unscrew and replace it to check for sparks as you crank.
You shouldn’t need to check all the plugs, you’re looking for a spark, not finding a misfire. One should be enough.

#5

Are you certain you have fuel in the tank?
Silly question maybe but it wouldn’t be the first time.

#6

The needle reads half a tank. Is there a chance the needle isn’t reading right?

#7

I’ve undone a plug with a 16mm socket. How do I remove the plug though? Its deep in the hole…

#8

On reflection, if you’re a member of the AA or similar and you’ve never removed a spark plug, maybe you should call them out.
Once you’ve checked you definitely have fuel in the tank that is…

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#9

Pliers?? Piece of garden hose?
Grease in your socket??
Dedicated plug sockets have rubber inserts in them for this very reason

#10

When you come to replace the plug in its thread, be very careful not to cross thread it. You’ll be in real trouble if you do…
Use no more than finger pressure when starting the thread, leverage should only be necessary to nip it up

#11

I may call a mobile mechanic… seems like it may be safer!

Thanks so much for your help so far!

Darren.

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#12

Probably wise.
Do keep us posted.

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#13

Quite a while since I had an MX-5, but I do remember the Mk2 versions have a crankshaft position sensor, which, if it fails, will stop the engine from firing up. Worth getting it checked.

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#14

With that obd code you quote I would check the MAF.

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