Intermittent Failure To Start & cutting out.

[RussellS]

Hi, this post is regarding my sons 2002 1.8 MX-5.

On a few occasions the car has failed to start. When you turn the ignition key, the dashboard lights will come on but the starter motor will fail to turn. My son reported that he could hear a faint click sound from behind the dashboard (presumably a relay). We also turned on the headlights and tried again and the lights did not dim when attempting to start the car. Then after a few attempts the car would start fine and would not give any further problems until the next time it would happen again which could be days or weeks later.

This has happened on a few occasions and it doesn't appear to matter if the engine is warm or cold.

Then today something different happened which I am assuming is related. He had been driving around 20 miles from cold when the speedometer needle started fluctuating wildly, the engine seemed to loose power and then the engine cut out completely. Also the dashboard lights and stereo all went out and came back on as if the ignition had just been turned on. After this the same scenario as before occurred whereby when the ignition key was turned the dashboard lights would come on but the starter would not turn. This happened for a few attempts and then the car started fine and has been fine for the rest of the journey (around 110 miles).


As I said, I'm assuming that these two issues are related. Could anyone offer any advice on this please.


Many thanks

Russell

[blackyb]

Waynes yer man on this type of problem, sure he will drop by soon and give you some direction.

[Mazda Mender]

Check the passenger side foot well under the carpet for water or damp, the ECU lives there and hates damp.
M-m

[Colin S]

Well it sounds electrical, Have you run a diagnostic to see if it throws up any faults? Does it have an after market immobiliser?

I would start with checking the battery connections are clean and secure. (easy stuff first!)

My next move would be to check the starter motor connections ( be careful as shorting the main power cable to earth can make rather a bang so may be worth disconnecting battery first.)

Next would be to check the connections on the ignition barrel, and then the connections on the ECU and immobiliser

If this does not identify the problem then it is a case of checking through the connections on each relay,etc

[RussellS]

Thanks for the advice guys.

Well it sounds electrical, Have you run a diagnostic to see if it throws up any faults? Does it have an after market immobiliser?

I only have a cheap OBDII tool but it reports that there are no faults listed. As far as I know it is a factory fitted immobiliser.


We checked the drain tubes tonight and found that they are completely blocked solid and my son said that after heavy rainfall the car does have a slight damp carpet musky smell inside. So we will clear them out and check for damp under the carpet in the passenger foot well and check all the ECU connections.

We'll check all the other things you suggested as well Colin.


I'll report back and let you know what we find.

[Lazza]

Did you check the sill drain holes as well as the hood drain tubes?

[RussellS]

Did you check the sill drain holes as well as the hood drain tubes?

No, I didn't but it is on the list for the weekend. Thanks

[Lazza]

They are probably even more important than the hood drain tubes. If the tubes are blocked, water gets into the sills. If the sill drains are blocked the water has nowhere to go but into the car, usually into the footwells.

[RussellS]

Sorry it's been a while reporting back but I've had a lot going on.

Anyway, as I reported the hood drain pipes were completely solid and took a lot of clearing. It was difficult to tell if the sill drain holes were blocked or not but we have cleared them anyway.

The battery connectors seemed a little loose to my so we cleaned the lubricated them and made sure they are good and tight.

I lifted the carpet and felt underneath where the ECU is but it didn't feel damp at all. So we are just going to wait and see how it is and if there is still issues then we will get to the ECU properly and check/clean all the connections.


Thanks for all the advice.

Russell

[flea]

Well done. Fingers crossed