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Hi There

I have an intermittent problem with my NB losing power. Initially it was on startup but now can happen after about 5 minutes of driving.

When it happens:

- the car struggles to go above about 3000rpm
- there is a distinct loss of power - car accelates very slowly
- when stoppped, the car idles really badly (i keep pumping the accelerator to stop it from stalling)
- there is a smell of unburnt petrol
- when it happened on startup, usually the car would reset itself after a km or two and the car would lurch forward as it returned to full power.

I've scouted other forums and it seems that perhaps the coil pack has gone.

Does anyone know if there is a way to test if the coil pack is the problem without buying a new one?

Does anyone have any other ideas about what the problem might be?

thanks for your help.

First step: Replace spark plugs - Budget $40
Second Step: Replace plug leads - Budget $80
Third Step: Replace o2 sensor - Budget $150
Fourth Step: Replace coil pack - Budget $500 (new) or about $100 used


My car was doing similar, it was fouling a plug and then running on 3 cylinders.
If that is the case, new plugs should get it running again, but only temporarily until it fouls one of them (you can clean the plug off with carby cleaner)
It may just be that the plugs are really old and due for replacement.

The leads can cause misfiring if they are worn and arcing against something. Checking them with a multimetre won't show any problems, best to just put new ones on (or borrow some from a running car. NA6/8 plug leads fit the early NB)

On my car the issue was the o2 sensor giving a bad reading, causing the car to run too rich, foul the plug, etc.
In my case a new o2 sensor fixed the issue.



Ideally I would replace the spark plugs and borrow some plug leads first.
If that works, then perfect. If not, then look into other items.

Thanks very much for the helpful advice.

My dad has a 1994 NA, can I use its o2 sensor on my car when if i get to step 3 & is it an eazy swap I.E what’s involved?

thanks again

You can definitely get coil packs checked and at no cost apart from the time to remove anda take to a ignition specialist. You can remove leads at idle to see which cylinders are affected.. You can also get a diagnostics guy to check for fault which they can do if the fault is evident ie misfire. There are a number of things that can cause the problem

jayjay wrote:Thanks very much for the helpful advice.

My dad has a 1994 NA, can I use its o2 sensor on my car when if i get to step 3 & is it an eazy swap I.E what’s involved?

thanks again

I'm pretty sure the wiring is different, the NB has a 4 wire sensor (since it has a heating element in it) the NA6 one is a one wire sensor (no heating element)

From memory the NA8 one is a 3 wire sensor, so you may get it to work, but it will need a bit of stuffing about.





Replacing the sensor is fairly easy, some sensors come with the Mazda plug attached, others are bare wires and need to be spliced in. The Splice ones come with instructions, my Bosch one came with a small watertight box thing to make the wire joins very neat and safe.

The hardest part will be removing the sensor from the exhaust, they are often wedged on extremely tight, so you'll need a good breaker bar, and soak it with WD40 the day before.
I'd recommend buying an o2 sensor socket as well, they have a cutout to let the wires through them, and are stronger than normal sockets to prevent them from slipping.



I'd do the spark plugs first still, you can borrow the plug leads from your dads they're the same as NB (take note on your car of the plug positions at the coil end though, I think the order changed. From memory NB is 4-1-2-3

Do you know anyone else with the same model? you could swap parts one at a time between the good car and the shat car and see when the problem transfers.
if your around wollongong i have a spare coil pack you can borrow for testing.
rest of my cars fairly non standard.. though i have my factory parts somewhere..