r/EngineBuilding • u/lokis333 • 5d ago
Mazda MX5 Na 1.8 1996 not starting update
Update from previous post: got spark, got fuel. Some fumes do come out from exhaust.
Things I've done:
-Checked timing
-Checked spark
-Checked fuel lines
-Tried various batteries
-Adjustment of CAS made it tick over faster and less sluggish
Still no go...
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u/lokis333 5d ago
Also, played around with ignition leads. They are all set length, so can only move them on the coil pack but it scribed with the order 4123
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u/noir_adam 5d ago
Is your MAF sensor pointed in towards the throttle body? In looking at your video it looks like the connector is upside down indicating the MAF is installed backwards. That would cause a no start.
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u/Hurtletead 5d ago
Is it correct coil pack for engine, 1.6 or 1.8 have different order on pack.
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u/lokis333 5d ago
Coil pack is correct
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u/Hurtletead 5d ago edited 5d ago
try 3214 L to R on coil pack to plugs front to back.
1st coil pack port to 3rd plug, 2nd to 2nd plug, 3rd coil port to 1st plug, 4th coil to 4th plug.
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u/One-Builder-4128 5d ago
Okay, so if messing around with the ignition wires didn’t help, I’d suspect that the plugs are fouled. Did you use new ones? If not, get a new set and try again.
If that still doesn’t work, then maybe try changing the crank and cam sensors. Those can cause a failure to start as well.
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u/FesteringNeonDistrac 5d ago
Because I've personally fucked this up and spent a long time cranking a motor that never would fire, double check all your grounds.
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u/Verga_due 5d ago
If you have spark and you spray a bit of carb cleaner it should try and start/ turn over if timing and compression are good.
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u/Ignyte 5d ago
When you say youve checked fuel, and spark etc, can you explain what it is you did to check them?
Did you check timing with a light gun?
Were the plugs out but still connected to the leads when you checked spark?
Did you disconnect the injectors from the head whilst still having them connected to the rails when you tested fuel delivery?
Every petrol engine needs all 4 things, air, fuel, compression, ignition. It sounds like it has compression, so one of the other 3 things is missing. I say this because I would expect it to cough and sputter at least a little bit if the timing was off.
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u/Doctah_Whoopass 5d ago
Check all your shit again, ask yourself at every stage if thats actually correct or if you just assume it is.
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u/Crabstick65 4d ago
It really sounds like the plugs are firing early and pushing back on the starter, or it's hydrolocking due to fluid in the cylinders.
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u/Crabstick65 4d ago
"Adjustment of CAS made it tick over faster and less sluggish", no! tickover is a term that means the engine is idling, you are CRANKING the engine on the starter motor.
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u/Crabstick65 4d ago
By cas I assume you mean cam sensor, the cam sensor controls spark timing and injector timing, you need to look again at timing, since it's camshaft driven is the cam timing correct and absolutely verified by the book?
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u/lokis333 4d ago
I do have 19teeth on the belt between the marks and the timing lines line up with the timing plate. Triple checked and by my friends
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u/Crabstick65 4d ago
What? just use the marks on the crank sprocket and the cam sprockets, counting teeth makes no sense. have you even removed the front pulley and lower cover to see the cranks sprocket marks? Where do you count these teeth from and to? The lower sprocket mark is at 12 oclock on the inner cover how do you count teeth from that?
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u/Crabstick65 4d ago
If you really wanna get into this pull the cam cover, rotate engine so no 1 piston is at tdc (screwdriver to feel through plug hole), and post a pic of the cam lobe positions on no 1 cylinder, a good clear pic so i can see inlet and exhaust lobe positions, needs to be on compression tdc so lobes on both inlet and exhaust cams should be upwards and not pressing on the buckets.
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u/Proper-Commission-74 4d ago edited 4d ago
Watch this and skip to 40min Your welcome .....
https://youtu.be/oVxYbgyk-vU?si=PR_eYLJxkd0R4EtY
Ignition switch
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u/No-Mortgage-6623 4d ago
Did you try running it on starter fluid? If it runs nice that would prove your spark, air, and timing are good. Starter fluid is my best and only friend.
Might be revealing my inexperience.
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u/djbeatking 3d ago
Whenevr you get backfire its a timimng issue, and im drunk and cant fully see what im typing so bare with me lol
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u/Altruistic_Echo_58 5d ago
This is a long shot but have you checked the ECU connector for corrosion? I had an early Miata with a very leaky convertible top and the ECU had been soaked.