Common starting problems.

[Slyjoe]

Hi all, 3 weeks into ownership and this morning the car would'nt start.
Been a while since i've been under the bonnet.
Remind me of common things to look for. ('98 import 1.6)
It turned over at a reasonable rate but wouldn't catch. -Thought it might once or twice.
Drove fine last night.
Does have an aftermarket immobiliser - was turned off - so not that.
Wiggled the leads, no difference.
Didn't have time to check for spark or fuel.
Any help appreciated.

[MX-5 Lazza]

I would suspect the immobiliser...

[NeoVR]

immobiliser... or CAS sensor

[Slyjoe]

Well, I jumped it this evening, it was reluctant and lumpy for a tiny bit, then ran like a dream.

The battery tested fine for 14v constant with powering lights on and off etc.
Any ideas?

[Slyjoe]

So I replaced the plugs and leads, and when running it goes like awesome!
However it still does not like mornings - takes ages firing and chugging on one or two cylinders, full boot of accelerator then it might catch and go.
Any ideas?

[MX-5 Lazza]

Water temp sensor on the back of the block?

[Slyjoe]

MX-5 Lazza said:

Water temp sensor on the back of the block?

Would I be right in assuming that sensor would affect the mixture if it was sending bad signals?
The thing is, because it only occurs when stone cold, I dont want to throw a load of cash at a garage who will then change loads of bits unnesarilly, only for the problem to re-occur 2 weeks down the line.
Thanks Lazza I will check that one out.

[Gizmo!]

Sounds like damp in a sensor or a lead somewhere. Mine was a bit spluttery on Monday evening having been parked on muddy ground for a couple of weeks, but a good "italian tune-up" and it's running sweetly again.

[Mazdamender]

It could be the choke sensor? but i would also check for any water on the pass side near the ECU? sounds like an ECU fault?

Edited by Mazdamender on Wednesday 15th September 09:39

Edited by Mazdamender on Wednesday 15th September 10:10

[Slyjoe]

Mazdamender said:

It could be the choke sensor? but i would also check for any water on the pass side near the ECU? sounds like an ECU fault?

Thanks for taking the time to reply.
Odd thing is, yesterday morning - tiddling down with rain, it started on the first crank - it was a warmer day though.
This morning, glorious sunshine, but a bit colder, not a fricking chance, just would not catch and fire.
Mazdamender, i'm not sure I understand what you mean by "water on the pass side?"
Had to drive to work in a souless box.

[Mazdamender]

Slyjoe said:

Mazdamender said:

It could be the choke sensor? but i would also check for any water on the pass side near the ECU? sounds like an ECU fault?

Thanks for taking the time to reply.
Odd thing is, yesterday morning - tiddling down with rain, it started on the first crank - it was a warmer day though.
This morning, glorious sunshine, but a bit colder, not a fricking chance, just would not catch and fire.
Mazdamender, i'm not sure I understand what you mean by "water on the pass side?"
Had to drive to work in a souless box.

Sometimes rain/water can get in on the pass-enger side footwell, and can give you problems with the ECU sat in it? just to be on the safe side ,just check she is dry in that area,lift the carpet up ,and up on the bulk head you will find it there.
I would unplug the the batt, and unplug all the connections to the ECU give them all a blow and reconnect, it could just be a dry connection?and it will not cost you anything to try,just a bit of time you never know.
Are you anywhere near manchester?
Regards
Wayne

Edited by Mazdamender on Wednesday 15th September 17:48

[Slyjoe]

Mazdamender said:

Slyjoe said:

Mazdamender said:

It could be the choke sensor? but i would also check for any water on the pass side near the ECU? sounds like an ECU fault?

Thanks for taking the time to reply.
Odd thing is, yesterday morning - tiddling down with rain, it started on the first crank - it was a warmer day though.
This morning, glorious sunshine, but a bit colder, not a fricking chance, just would not catch and fire.
Mazdamender, i'm not sure I understand what you mean by "water on the pass side?"
Had to drive to work in a souless box.

Sometimes rain/water can get in on the pass-enger side footwell, and can give you problems with the ECU sat in it? just to be on the safe side ,just check she is dry in that area,left the carpet up ,and up on the bulk head you will find it there.
I would unplug the the batt, and unplug all the connections to the ECU give them all a blow and reconnect, it could just be a dry connection?and it will not cost you anything to try,just a bit of time you never know.
Are you anywhere near manchester?
Regards
Wayne

This is why PH is awesome - the collective hive of knowledge is un-toppable!
I'll check all of those things, I also made a code reader to see if the ECU spits out any faults.
No-where near manchester unfortunately - heard its lovely this time of year
I'll report back when things have been checked and improved.
Many thanks again.

[Slyjoe]

Update to my problems.
So far I have replaced, Plugs - gapped properly, HT Leads, Cam Angle Sensor, Air Intake Sensor (temperature), Coolant temperature sensor, Coil Pack, I have checked for dry or damp connections to the ecu and battery,
And still the bloody thing will not start for ages.
The battery will turn it over at a good speed for a good 10 minutes, with my accelerator flat to the floor and the clutch in, it will catch for a bit seemingly on 2 or 3 cylinders, and will always eventually get going.
I say foot flat to the floor, as if I don't it wont fire at all.
When its running it does not miss a beat, pulling strongly.
Anyone have any more clues as to what might be wrong?
Thanks.

[maser_spyder]

MAF sensor?

Not the first thing I'd have chosen, but they do go wrong, and you've changed nearly everything else!

[freddytin]

Attempt to start the car, for say 10 to 15 secs.

Remove all the plugs and see which 2 are doing the work. I would suspect head gasket , and would be looking to see if there was any coolant on the misfiring cylinders plugs.

[Slyjoe]

freddytin said:

Attempt to start the car, for say 10 to 15 secs.

Remove all the plugs and see which 2 are doing the work. I would suspect head gasket , and would be looking to see if there was any coolant on the misfiring cylinders plugs.

Ah-ha, armed with that and google this very forum threw up a similar problem.

mx5rob said:

The symptoms where just problems starting. It would turn over but not 'catch'. I tried changing plugs and leads as well but no joy.

I took it to a local independant Mazda specialist who took a while to diagnose it. It was excessive wear on the valves due to poor material. Mazda have a service bulletin for the problem and I think the best way of telling is to measure how well the valves sit. If its the same problem then there will be an excessive gap.

Mine is an S reg MK2 and this problem only occurs for the first few months of production so it may be a different issue if your a T reg ... but it might be worth mentioning to your dealer/garage to see if they can check it.

Bearing that in mind, if it does appear to be the problem can anyone give a ballpark figure as to what costs I might be looking at? and what else would be prudent to change at the same time?
Many thanks again.

[freddytin]

^^^Surely a simple compression test on start up would show poorly seated valves, no ? ^^^

Edited to add..... If the compression is indeed low on initial start up, then I would think the cranking RPM would be noticeably higher than normal.

Edited by freddytin on Thursday 7th October 19:32

[Slyjoe]

freddytin said:

^^^Surely a simple compression test on start up would show poorly seated valves, no ? ^^^

If the compression is indeed low on initial start up, then I would think the cranking RPM would be noticeably higher than normal

True, and its cranking speed is not higher when cold.
Surely though if its the head gasket I'd be seeing mayonnaise oil with the filler cap removed, all I can see is lovely black oily cams.

[freddytin]

Slyjoe said:

freddytin said:

^^^Surely a simple compression test on start up would show poorly seated valves, no ? ^^^

If the compression is indeed low on initial start up, then I would think the cranking RPM would be noticeably higher than normal

True, and its cranking speed is not higher when cold.
Surely though if its the head gasket I'd be seeing mayonnaise oil with the filler cap removed, all I can see is lovely black oily cams.

Early stages of head gasket failure often show no apparent indications,

I think there may be a slight breach of the cylinder from the head gasket to the water jacket ,and what can occur is when the engine is shut down there is no residual pressure in the cylinder, but the water system retains its pressure for some considerable time .Consequentially a small amount of coolant enters the cylinder wetting the plug, causing starting difficulties.

Edited to combat sticky fingers

Edited by freddytin on Friday 8th October 08:37

[Xenocide]

There was a similar problem i read somewhere which was something oily related, there was no compression because the hydraulic tappets/whatever wern't getting oil pressure so wouldn't start.

Not sure on the details but might be worth thinking about the lubrication system .