NB won't start - no spark, coil pack?

[nickt93]

About two weeks ago I was driving my NB and the engine died - I pulled over, but couldn't get it started. I got towed home with a tow strap, and have just had the chance to do some diagnosis.

I used an inline spark tester to see if it's getting a spark, and it looks like it is not. I tried cylinders from both coil packs, and it looks like neither is firing (I did faintly get a spark momentarily on cylinder #3, but it was just a quick flash while trying to crank the car.

Right now I think its the coil pack. Are there any other common issues in the NB that I should be checking into? Does anybody have a spare coil pack for a '99 that I could use to test? Or, does anybody have one for sale?

[miatastuff]

I have a spare coil pack, but if that is it, it should have a CEL.

[RotorNutFD3S]

99/00 coil packs are notorious for failing, and FWIW I've seen them fail with and without the CEL.

[miata5620]

yeah i just had mine fail but you should have had some misfires which would have thron the cel. not an expert but from everything i read its rare for them to just stop working without having misfires.

[nickt93]

Thanks guys. The check engine light is lit, but I wasn't sure if that was caused by there being an issue or because quite a few dash lights seem to light up with the key in the ACC/RUN position when the engine is not running.

I attached a pic of the dash lights with the key turned on - brake, battery, and CEL are all lit. Does the CEL normally light with the key in the run position/engine not running, or does this indicate a problem?

As for misfiring, the car was stumbling a bit from time to time, but I thought that was just working out some kinks since I recently resurrected this car from the dead (sat for about a year non-running).

Is it uncommon for both coil packs to fail at the same time.

The Parts Group sells a pair of '99-00 coils for $149. Seems like a good price - any cheaper sources? David - PM me if you are selling the spare that you have.

[miata5620]

Are the parts group coils new or used if they are new great price if used not a good price. I got a set from mazmart for around $170. I don't know about them both failing being common mine had only one fail.

[mustangtomiata]

All the lights were on in my car with not running but in the run position. Rare for both to fail at once, but I could still see it happening.

[ben91]

The CEL will be lit with key on and engine off, just to show you that the bulb still works. There very well could be a code in there you should get scanned.

Is the car squirting fuel when cranking? Does the tach move when cranking (this is hugely informative).

I would be looking more at things like the crank position sensor. You'll see it on teh driver's side of the crank. Make sure it's plugged in and check the gap on the sensor, should be about a business card thick. Make sure the cam sensor is also plugged in.

I would not imagine that *both* coil packs would fail at the same time. One or the other go, sure that happens all the time. Have you tried looking for spark with an actual plug instead of an inline tester? A spare sparkplug makes it easy to check without having to actually pull plugs. If no spark, then I'd pull the pigtails off the packs and check for power and ground. You'd need a scope to check for trigger.

Not to take anything away from Tom (he's a nice guy and all), but $150 on a used pack is a bit on the steep side.
If you need stuff to borrow, I know for sure I have a good set of coils, and probably also have crank and cam sensors somewhere.

[Cool Cat Racing]

New coil packs at most parts stores are about that price so if thats used its way high. I'd personally bet its the cam or crank sensor. Most of the time I get crank sensor failures its because the wiring came into contact with the belt or something hit the sensor. I seriously doubt its the coil packs since neither is firing. Check the crank and cam sensors and also check the air gap on the crank sensor. If its on the verge it may have been causing your hiccups and now just doesn't work. If that's the case you can just reposition it and it will work fine.

[nickt93]

Thanks a ton guys...this kind of information really helps. Here are answers to a few of the questions posted above.


Is the car squirting fuel when cranking? Does the tach move when cranking (this is hugely informative).

Interesting...just tried cranking the car; no tach movement. Does this point to the crank angle sensor? I haven't specifically tested fuel yet, but when I pull a plug after cranking there is a strong odor of fuel.


Have you tried looking for spark with an actual plug instead of an inline tester? A spare sparkplug makes it easy to check without having to actually pull plugs.

Can you elaborate a bit? Do I just pull the boot off of the plug and crank the engine with the plug in free air? I wasn't sure if that was safe or not...thought the plug had to be grounded against the engine or something.


Not to take anything away from Tom (he's a nice guy and all), but $150 on a used pack is a bit on the steep side.

$150 is for new coils
http://partsgroup.com/store.aspx?category=Miata-Electrical&Page=3

[ben91]

To watch a plug spark, you just install it on the plug wire (obviously the other end of the wire must still be on a coil). Set the plug down on top of the valve cover, making sure there is contact between the steel part of the plug and the valve cover itself, and have someone turn the motor over while you watch. Obviously don't touch anything while it's sparking, otherwise you'll get a surprise you won't like.

No tach points to a missing ignition trigger, cam or crank. The car's likely to have stored a code, so just scanning it should point you in the right direction. I just looked on my extra motor, and the crank sensor is already gone. But I have a cam sensor. Crank sensor is the same 99-05, so someone like miatastuff should have a supply of them.

If you don't have a scanner, easy thing to do is look for the crank trigger on the driver's side of the crank pulley. Follow the wiring harness, make sure it's undamaged and actually plugged in. Also check the gap between the sensor and the trigger wheel (there's a weird toothed wheel behind the crank pulley, it only has 4 unevely spaced little teeth so it might be hard to identify if you're not familliar with a trigger wheel). There is of course a proper technical spec for the gap between the sensor and the outer edge of a tooth, but I don't know what it is. I've always used a business card to gap the sensor in every car I've ever owned...lawnmowers too. :)

[nickt93]

So I finally got a minute to look at the car and try to diagnose the issue. I popped the hood and noticed almost immediately that the bolt that holds the camshaft position sensor had backed out a bit - almost to the point of falling out. Screwed it back in, turned the key, and the car fired immediately. Damn I love an easy fix.

[Sawyer]

Nick, you always have the best luck. You got this car for stupid cheap, got it running with an easy fix, and when something goes wrong you just have to screw a bolt back in?! Damn, I wish everything in my life was that easy! :lol:

[RotorNutFD3S]

Nick, I'm nominating you to find my next Miata.

[ben91]

So I finally got a minute to look at the car and try to diagnose the issue. I popped the hood and noticed almost immediately that the bolt that holds the camshaft position sensor had backed out a bit - almost to the point of falling out. Screwed it back in, turned the key, and the car fired immediately. Damn I love an easy fix.Totally fit the symptoms. Good job dude.

[nickt93]

Nick, you always have the best luck. You got this car for stupid cheap, got it running with an easy fix, and when something goes wrong you just have to screw a bolt back in?! Damn, I wish everything in my life was that easy! :lol:

I was thinking the same thing! This car has been way too easy on me. I, too, wish everything in both life and the car world could be this easy.

Nick, I'm nominating you to find my next Miata.

You just let me (and everyone here for that matter) when you are ready to find another Miata and it will be all hands on deck!

Totally fit the symptoms. Good job dude.

Thanks for your help all along the way...I'm glad I didn't rush out and buy a coil pack.