Burning smell, loss of spark? Need help to fix FAST!

[pietro]

Hi all. My Micra died today and I need in on the road ASAP.

What happened...

Driving along today and smelt a buring small (thought it was the car infront).

I had just changed into 4th gear when the engine died.

Pulled over presuming it was my aftermarket electronic ignition and switched it to by-pass. Still no spark (even from the coil). I presumed it must be my coil so I changed it with a new spare and still no spark? I then changed the electronic ignition with another spare I had, still no spark?

There is no shortage of batery power? What could the fault be, I have checked all the fuses too.

Thanks guys!

 

[Ed]

well you have a burnt wire somewhere. check that with the ignition ON there is 12v going to the coil for a start then you can go from here.

 

[pietro]

Checked, power is going to coil? This is weird?

 

[Ed]

no not really the K10 ignition is very simple. If there IS power going to the coil its not a hard job to find. next take an earth wire from the battery and touch it against the earth contact on the coil and observe if you get a spark from the end of the lead on a sparkplug, (connect a sparkplug directly to the coil ignoring the distributor and place it on a metal part of the engine..

Make sure the ignition is ON whilst you do this and you have 12v on the other side of the coil and be AWARE that there may be VERY high voltages so DONT touch any of the HT stuff.

As you touch the Ground wire to the ground on the coil you should see and hear a spark.

Ed

 

[pietro]

Thanks Ed I will try this.

I have also been told to check the points to see if there intact as a pulse is ncessary to actvate the coil (hence no spark)>

I will check this then do what you said Ed. In the meantime any further suggestions or help would be apprecated.

This may help with explinations:

Image: http://www.sonirodban.com/ignition-system-points.gif

Text: The distributor handles several jobs. Its first job is to distribute the high voltage from the coil to the correct cylinder. This is done by the cap and rotor. The coil is connected to the rotor, which spins inside the cap. The rotor spins past a series of contacts, one contact per cylinder. As the tip of the rotor passes each contact, a high-voltage pulse comes from the coil. The pulse arcs across the small gap between the rotor and the contact (they don't actually touch) and then continues down the spark-plug wire to the spark plug on the appropriate cylinder. When you do a tune-up, one of the things you replace on your engine is the cap and rotor -- these eventually wear out because of the arcing. Also, the spark-plug wires eventually wear out and lose some of their electrical insulation. This can be the cause of some very mysterious engine problems.

Older distributors with breaker points have another section in the bottom half of the distributor -- this section does the job of breaking the current to the coil. The ground side of the coil is connected to the breaker points.

A cam in the center of the distributor pushes a lever connected to one of the points. Whenever the cam pushes the lever, it opens the points. This causes the coil to suddenly lose its ground, generating a high-voltage pulse.

The points also control the timing of the spark. They may have a vacuum advance or a centrifugal advance. These mechanisms advance the timing in proportion to engine load or engine speed.

Spark timing is so critical to an engine's performance that most cars don't use points. Instead, they use a sensor that tells the engine control unit (ECU) the exact position of the pistons. The engine computer then controls a transistor that opens and closes the current to the coil.

 

[Ed]

If you do as I say in the above post we can begin to round the problem down to its cause as quickly as possible...

 

[pietro]

Hi Ed.

I did as you said, I bridged the earth wire from the battery against the earth contact on the coil, there was no spark.

I opened the distributor and the points look perfect, they open and close when the starter motor turns.

I then took the wire from the coil off and held it against the body of the car (earth) and switched the ignition on and then off, there WAS a spark!?! Not blue, more orange (don't know if this means anything?).

I then tried to start the car while holding the distributor supply wire to earth expecting a spark pulse, there was nothing? I checked at the plug end too, again no spark?

What now please?

Thanks!

 

[Ed]

Ok so lets recap.

When the ignition is ON you should have a CONSTANT 12V to the coil. You have already said you have this. (which is good)

Then with the ignition still ON you have taken an earth wire (-) from the battery to the other side of the coil, with a HT lead direcly from the coil to the sparkplug, when you touched this against the coil there was NO spark?

Right? If so that points to the coil. I dont quite get what you mean about ignition on then off. That could mean lots of things and is not very clear..

All the tests ive talked about so far require the ignition to be ON if thats not the case then try again..

If you just check what I have said is what you have done so far then we can move on to the next test.

 

[pietro]

Hi Ed.

I did this:

"Then with the ignition still ON you have taken an earth wire (-) from the battery to the other side of the coil, with a HT lead direcly from the coil to the sparkplug, when you touched this against the coil there was NO spark?"

However I did not connect a spark plug as I did not think it was necessary, I can get a spark at this poing when I turn the ignition on then off (regardless of weather I switch the key further to activate the starter motor).

I have also bypassed the electronic ignition.

Could the fault be the condensor in the distributor?

Thanks

 

[Andrew]

The coil has a permanent positive supply, and the negative is switched. You only get a spark when you connect or disconnect the ground, not when it is connected permanently. You need the ignition on, and then tap a wire on the negative terminal. You should get a spark here (from the back EMF), and also one from a plug connected to the HT terminal.

If that is happening, then the coil is functioning.

If the condensor is shot, you get a weak spark as most of the energy is being dumped across the contact breaker. You had electronic ignition though, which negates the need for a condensor.

 

[Ed]

Do it again the way I said. Im keeping each step small and simple. In any case it sounds as if you do have 12v and the coil is working. The only thing then left is the wires from the coil to the distributor and the contact points. Those wires can break and you not even beable to tell so, I have had it happen to me, so now look at those.

 

[pietro]

Hi All.

Just to recap:

I fitted a NEW coil and have bypassed the electronic ignition.

I need to know why when I turn the ignition on and then off I see a spark from the coil (this is with the wire from the coil off and held it against the body of the car (earth)).

However I see no spark when I try and start the car with the starter motor churning? Anyone know?

I now think it is something to do with the wires from the coil to the distributor, the contact points or the distributor housing, which one of these could it be? Everything looks fine to me.

I also went to Nissan and spoke to parts, they told me that the only way a 1988 K10 pre-electronic ignition developes this fault is when the wire in the distributor housing breaks due to a poor install. I bought another for £1.40p however my distributor housing did not contain this wire? It did contain another wire which I took off but I now can remember where it goes! Ahhh. The haynes manual is usless! The diagram is un-usable!

Does anyone have a photo/link so I can see what the inside of the distributor looks like, at the moment I have wired it too look like this: http://www.sonirodban.com/ignition-system-points.gif I presume fia A is the positive pulse imput from the coil right?

Help needed all!

Thanks!

 

[Ed]

Point A is the negative switch for the coil. It triggers the negative side of the coil to ground. It will be somwhere around here that you have a problem I suspect. You may need to run a new wire from the negative on the coil to point A. Also you should check that point B (lower) and the negative coil wire are of low resistance. If this is not the case then that is your problem..

Ed

 

[pietro]

Thanks Ed. I will try this tomorrow.

Also I was looking in the Haynes manual and found a photograph of the inside of the distributor (page 4.2 on the 1996 edition). I can see how everything should be connected however on this image the condensor is on the outside? Mine was on the inside, I also presume it is original as the car had only 23k on it when I bought it. What does the condensor do?

Thanks

 

[Andrew]

The condenser stops arcing between the points (which rapidly destroys them). It also ensures the spark is powerful. In an electronic ignition which is triggered using the points, very little voltage/current flows through the points and a condensor isn't needed.

 

[pietro]

Car Now Fixed!

I can confirm the electronic ignition failed taking the coil with it. While investigating I set the points up the opposite way they should be (ahhh human error!), anyway its all sorted now. Thanks for the help guys!