Totally agree with above, you have done the hard work finding the fault just need the cause, I was trained as a fitter for British Rail working on the rolling stock and we were taught to break the brake the fault down. You have proved 12volts at the coil pack so now just to need confirm the inputs to the coil pack. Reading through the thread I dont believe the cam/crank sensors can be out of alignment or the car would have never run, however I had a similar problem on a X5 the car would start drive fine, I would park up then 10 minutes later it wouldnāt start for love nor money then it would be fine for weeks eventually it turned out to be the cam sensor intermittent.
Which has a small black box stuck under the steering column with loads of black wires around It, and a little flashing red light when the ignition is turned off.
And I have an immobilizer on the key ring which sorry to say but looks like a thin version of a supositary.
And if that is not on the keys then the car will still turn over quite happily but will not start until you put the immobilizer fob near the ignition barrel and then try and it will start.
So my question/answer is have you got the immobilizer fob on the keys when trying to start it.
If you have then take it to Mazda to see if it is still working.
Sounds to me like you have a 3rd party immobiliser on your MK1. This car had a 3rd Party Alarm with immobilisation fitted too but I was told the problem started many years after this was fitted so I suspect its not the problem but despite that it was one of the first things I eliminated (I think) by tracing the wires back and isolating any alarm wires and re-implementing the original loom wires. This consisted of an isolation at the ignition column and another near the accelerator pedal, so I believe that was both parts of the alarms immobilisation for Ignition and Fuel.
I know Mazda does have factory immobilisation on some cars too but according to the carās handbook, this is identifiable by a ring around the ignition key lock which mine doesnāt have.
Exactly my approach, I was Senior Engineer and then Engineering Manager at Doncaster Works and always instructed test engineers to work backwards from the known fault and not to get side tracked looking at other possible faults. Also only replace possible faulty components with known good ones from a working unit. Hence why I said the OP needs to now look at coil packs and input from ECU. However you need an oscilloscope to see the trigger and so may need a good auto electrician who has one. After that the OP needs to check inputs into the ECU.
We used to dread trains coming in with a brake neg fault. I have known it take a week to fault find the defective dry joint.
The car is still garaged with no progress on the issue what-so-ever.
Its not been worked on all that time of-course but another guy I know did take on the challenge and failed to get any further than I did myself
As mentioned before, I did see another vehicle being sold with a similar fault but unfortunately, when I reached out to the seller, he never bothered to respond so let this be a warning to anyone thinking about buying a cheap non-runner with a no spark issue. It could be something really simple but it also could be an impossible fix
Are you 100% certain there is no spark on any of the plugs?
If that is the case, there has to be a reason for it and itās a matter of working back until you find whereabouts the fault lies until you can pinpoint it.
If this was a Ducati, Iād be saying you should check your fuses for connectivity. A fuse can be intact but not passing current due to light corrosion between fuse and fuse holder. A good wiggling can sometimes work wonders.
I would then be trying to establish if the coil packs are getting a trigger signal and as has been said, if that applies to all. Check wires for continuity, maybe with a test lamp rather than multimeter.
The fault has to be traceable.
Iām no expert BTW but with a lot of persistence and a lot of virtual assistance, I did manage to trace and fix two mysterious faults that were preventing a couple of Ducatis from running, one of them being a broken wire to the fuel pump that looked intact but wasnāt.
Like you, I swapped ECUs and all sorts before finally pinpointing the fault.
Also, like you, the engine would occasionally run because the broken ends of the wire were touching inside the insulation.
It was continuity testing that finally pinpointed the problem
Iāve just stumbled in this thread - new OC member with an 03 V2.5 1.8, browsing the forums for interesting stuff. Iām not sure whether my experience will be useful butā¦
I had a very similar fault in 2019, except that the fault was intermittent, so even harder to diagnose. Eventually we* discovered the problem was some loose pins in the immobiliser chip so it couldnāt
communicate correctly with the eeprom in the ECU. I donāt remember all the details, but I recall something about a 4 digit code being read (or written): when the loose pin was in contact, the correct code was exchanged, when there was no connection, the code was either not exchanged, or was incorrect, so the immobiliser stopped the ECO from firing.
Fixed by replacing both the immobiliser and ECU with a matched pair found on Ebay.
* When I say āweā, I mean the guy who had it towed to his premises and spent several hours checking all sort of things. My contribution tp the process was paying him lots of cash, but I got my MX5 back working perfectly
Iāve just rejoined as a member been off line for a few years. I had similar problem on my mk2, experts and RAC couldnāt fix. My engine cranked but no start/no spark.
You may have already tried this but Iāve not been through the whole thread.
On the back of the block is a ballast resistor/capacitor like the good old condensers. If this faulty you wont get spark and the imobiliser cuts fuel if no spark.
I repaced this and away it went.
Its not in the usual manuals but there is a reference to it in the circiuit diagrams online.
Iāve just come back after a long absence!
My MX5 engined Westfield is now turboād!
Iām looking for a nice NA to play with now.
Surprised you still havenāt fixed the issue?!
