No Spark - On going log.

Well, as the title says, I am having trouble getting a spark from the engine. Asking around there are so many things that can be the problem. So enjoy the list!

1. Poor earth connection
2. Faulty spark plugs
3. Faulty HT leads
4. Faulty coil pack
5. Faulty Mass Air Flow sensor (MAF)
6. Faulty Cam(shaft) Angle Sensor (CAS)
7. Faulty Crank(shaft) Position Sensor (CPS)
8. Faulty ECU
9. Built in immobiliser
10. Incorrect Wiring
11. Rust/Corrosion on connections etc.
12. Mx5 common fault of the coil pack
13. Starter motor issues
14. Various sensor issues
15. Faulty Relays
16. Ignition/Power feed issues.

This list is neither exhaustive nor specific. The problem could be a single problem or a collection of several.

Testing a couple of them is fairly straight forward and with simple tests can eliminate a few or leave you still looking for a solution but a little more direction on where.

Week of Saturday 27/07/2013 to Friday 02/08/2013

The route I took was measuring the earth points and ensuring power to the pack. Rumour has it that old 1.8 Mx5s had a problem with the coil packs where they would burn out if the ignition was left on but not running for a prolonged period. I must admit, figuring my lights out, it had been, plus with filling with fuel to ensure the air was as cleared out as much as possible. Despite the 1.6 versions not seeing this problem, on a 23 year old coil pack, it was a possibility anyway. Plus removing the HT leads revealed a rather sorry looking pack which had melted a bit and build up of electric dusting of some sort on the connections.
First thing to test was the earth connection. Remove all the spark plugs, lay the body of the plug on the chassis to ensure a good earth or link straight back to the negative terminal on the battery and crank it over.

• A spark means you have an earthing issue.
• No spark means you have eliminated the main cause that it isn't only an earthing problem.

Well I had no spark so I am still non the wiser. Next was to check I was actually getting power to the pack using a multimeter. Once I'd established I had power to the pack, but nothing on cranking, I have taken the plunge of buying a new pack, leads and plugs. I had already checked to see if the cams/crank were actually turning by removing the cam cover and watching the engine turn and spurt oil as it cranked, so that's all ok, the CAS should be working, if it isn't then that's probably the problem....in my opinion anyway. They are well known to be fragile.

My pack has arrived today, Friday 02/08/2013, so this weekend, hopefully the engine will be running....or at least make sure I am sparking as I haven't plumbed in any coolant hoses. Would hate to cook the engine before I'm even finished or spew any leftover coolant all over the engine bay! Probably just make sure I have a spark is the main thing....

Weekend Saturday 03/08/2013 > Sunday 04/08/2013

Ok, so new coil pack fitted, HT leads and spark plugs. After properly removing my old coil pack, it really did look bad, melted and build up of sh*t where the HT leads attach. Well that must have been the problem, burnt out and generally knackered.

Plugged in and ready to go.....nothing. Still no spark :(
Stuart (theduck - Rhocar) offered to come and check that it wasn't something obvious like a bad earth connection, however still have a load of head scratching and some proper checking, still no spark.

We settled that the ECU is the only thing that we need confirming to work considering all my power connections appear to be right, and is the only thing left from the separate donor that I don't know if it was actually running or not. So my plan is to take that to an MX5 breaker I know of and see if they will plug it in and try, see if it is working or not.

However, Stuart being stumped and having it bug him as to why is wasn't working, found a forum post from an MX5 forum which had similar issues and concluded it to be a faulty Mass Air Flow sensor. Now I wouldn't have thought this would be an issue and has caught a couple of guys by surprise, but for £30 second hand "tested and working", it is worth a shot. That is due to arrive this week. I can live with a second hand unit that is suppose to be working due to a brand new one costing £450!! :O

Anyway, coolant pipes are due to arrive the same time so will plumb that in properly before trying again, worse thing is getting it running and then cooking the engine!

Watch this space!

Friday 09/08/13

Success!!!

After fitting the "new" MAF sensor, the spark plugs sparked up first time! Big thanks to Stuart (theduck - Rhocar) for finding the relevant thread that suggested this solution. It now means I can really crack on with the build over the rest of the weekend instead of worrying about a knackered engine :) I am yet to give it a proper fire up due to not having the coolant plumbed in fully. Last thing I need now is to cook the engine!

Anyway, the cause for the MAF sensor preventing a spark is unclear. My understanding is that the sensor was causing the ECU to register no air flow, so possibly prevented putting in fuel and/or a spark. Other than that, I can't figure out the actual reason but it's sorted now so that answer will do.

Onwards and upwards!