car wont start! please help!!!!!

Black_Penguin · Postby **Black_Penguin** » Fri Oct 25, 2013 1:30 am

I would check plug leads, if these break down they can cause all sorts of oddball problems.
If you crank the motor are the plugs wet? ie have petrol on them?
I wouldn't go pouring petrol straight into the inlet manifold.
I would check and double check all the electrical connections for the motor and its sensors.

Postby **Okibi** » Fri Oct 25, 2013 2:08 am

Could also be an issue with an alarm / immobiliser

Check you have both spark and fuel first.

manga_blue · Postby **manga_blue** » Fri Oct 25, 2013 7:45 am

Okibi wrote:Check you have both spark and fuel first.

Try to start it for a few seconds then take out one spark plug. If the plug is wet then you have fuel. Reconnect a plug lead and hold the a metal part of the plug body against some metal on the engine and get a mate to try to start the car again. If you have ignition then you will see a spark arcing across the plug electrode.

Bad plugs, bad leads, bad coilpacks and bad filters don't normally make a car cut out completely, they just make it run progressively rougher. You probably have an wiring problem or a problem with a switch, relay, fuse or sensor.

If it's no spark and no fuel then it's possibly the FUEL INJ fuse (1 in the Main Fuse Block) or the MAIN or FUEL relay or a problem with the connection of the loom to the injectors and coil packs or faulty contacts within the ignition switch.

If it's just no spark then it's possibly the CAS.

If it's just no fuel then it's possibly the ST SIGN (9) fuse or an intermittent wiring connection to the fuel pump.

If the car starts and runs for just a second or two then it's probably a bad connection or internal fault in the AFM.

Swap components one by one with those from a mate's car before you decide to go and buy something expensive that you don't need.

Lokiel · Postby **Lokiel** » Fri Oct 25, 2013 10:33 am

See http://mx5cartalk.com/forum/viewtopic.php?f=18&t=59384&hilit=start for other tips, including a link to the "MSM Engine Won’t Start Diagnostic Checklist." - much of the info in it is applicable to non MSMs/SEs.

manga_blue · Postby **manga_blue** » Fri Oct 25, 2013 10:41 am

Almost forgot the obvious question. Okibi alluded to it. Has the car ever had an immobiliser fitted?

Postby **Okibi** » Fri Oct 25, 2013 11:14 am

Good point about the fuse, i've had a car that started but won't idle when the engine fuse has blown.

KevGoat · Postby **KevGoat** » Wed Oct 30, 2013 5:13 pm

I had this exact same issue in my NA6 once. Cranked fine and everything appeared working. Was told it was ECU. Car was trucked home by RAA. Talked to the previous owner who recalled similar happening to him - was just a slightly loose connection at the plug under the steering column to the ignition switch. Looked and felt connected and was connected enough that most things were working fine, but gave it a good push together and the car started. Held it tight with zip ties after that.

Maybe on off chance worth checking ...

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JBT · Postby **JBT** » Wed Oct 30, 2013 6:14 pm

I think there is some starting relay in the system that allows fuel delivery until the AFM senses airflow after the engine fires up. Maybe that relay or connection is dead. It sounds like an electrical problem.

Are the plugs wet after these start attempts?

sailaholic · Postby **sailaholic** » Wed Oct 30, 2013 6:21 pm

JBT wrote:I think there is some starting relay in the system that allows fuel delivery until the AFM senses airflow after the engine fires up. Maybe that relay or connection is dead. It sounds like an electrical problem.

Are the plugs wet after these start attempts?

If the injectors are spraying fuel I assume the only way he could test that was during cranking., so that probably says its not a problem with the system triggering the fuel pump.

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manga_blue · Postby **manga_blue** » Wed Oct 30, 2013 6:29 pm

Have you taken out a spark plug yet and checked that you can see a spark on the plug electrode when it's being cranked?

JBT · Postby **JBT** » Wed Oct 30, 2013 7:31 pm

sailaholic wrote:If the injectors are spraying fuel I assume the only way he could test that was during cranking., so that probably says its not a problem with the system triggering the fuel pump.

Yep, I agree - and I've found it's best to assume nothing on this forum. We still don't know if the plugs are wet and there is spark.

aka_juffa · Postby **aka_juffa** » Thu Oct 31, 2013 10:22 am

Are all plugs getting spark?...any other weird signs such as the taco not working?

Have you touched the plugs connecting to the ECU in the passenger foot well? I did this once (and then again :oops:

) with the battery still connected. It zapped the ignitor. The ignitor supplies current to the spark plugs. It is difficult to tell if the ignitor is stuffed. I ended up getting a follow NA6 owner to loan me his ignitor. A 2 minute job to swap it over. Car started first time.

Where are you located. Someone local to you on this forum may be willing to assist.

From (poor) memory the part is around $130 new. Super cheap can also order in a after market part, but you need to allow for a delay in the getting it.

Hope that helps.

J

manga_blue · Postby **manga_blue** » Thu Oct 31, 2013 11:29 am

So, you're positive that you have fuel in the cylinders and you have spark actually in the plugs. That probably means that the spark is not happening at the right time or the valves are not opening at the right time.

1. Take the oil filer cap off and make sure the cams are turning. Just pulling the car forward in 4th for a foot or two while you look will be good enough.
2. Remove all the plugs, connect a timing light to the number one lead, spin it over and see where the timing is.

sailaholic · Postby **sailaholic** » Thu Oct 31, 2013 11:50 am

manga_blue wrote:2. Remove all the plugs, connect a timing light to the number one lead, spin it over and see where the timing is.

If you use a newer style powered timing light you'll need to pull power from the battery to run it. The diagnostic port doesn't get power during cranking.

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