Ignition system not working (HELP!)

[dsio]

Ive had this 318i M10 sitting on the driveway for almost a month now unable to start.

I am getting an average spark on 1 plug (i think) but the other 3 range from bad to non existant. Using an induction tester on the leads, I couldnt even get a reading. I am convinced that three or all plugs are not sparking.

I know I have fuel getting to it, as I can smell unburned fuel very, very clearly comming from the exhaust, and the engine bay. I have put the injector cleaner in, and refilled the tank from bone dry to ensure there is nothing but premium unleaded and injector cleaner in it.

The air filter is brand new and flowing very freely, and the air box has massive holes drilled in it, so there is no blockage.

Upon pulling the spark plugs, they were all wet with fuel, and covered in carbon.

The leads are undamaged, and I did a continuity check on all four of them. 1, 2, and 4 leads have a resistance of 6.2Kohms, while number 3 has a resistance of 6.4Kohms, which I think is all about right. They are original BMW parts.

The Distributor cap appears to be ok, with some corrosion, but I dont exactly know what to look for in a damaged or worn cap. What should I be looking for in a dodge cap?

The arm looks like its OK, but I am wondering if the arm is meant to have a resistance in it?

Doing a continuity check from the centre point on the distributor, to the part of the arm that touches the points on the cap gave about 1000Ohms resistance, which didnt make sense to me, but is that normal?

I dont know about the condition of the coil, but I am assuming that the coil would cause it to quit completely rather than spark intermitantly.


When starting it, I often get 1 cylinder firing, then 20 seconds later a second, then SOMETIMES 20 seconds later a third cuts in briefly, and when I let go of the starter, it starts to labour and runs for a few seconds before stalling.

I really need help on this as the car has to be in service right now.

[stappin]

You sure the coil is ok?

[dsio]

I was not really considering the coil to be honest. I was told by someone that when the coil goes, it completely stops working alltogether. I get a small spark from time to time, on some of hte spark plugs, so there is a tiny bit of juice getting downstream from time to time.

Is that possible if the coil is bad?

[Brianmoooore]

I was not really considering the coil to be honest. I was told by someone that when the coil goes, it completely stops working alltogether. I get a small spark from time to time, on some of hte spark plugs, so there is a tiny bit of juice getting downstream from time to time.

Is that possible if the coil is bad?

Open circuit coil primary would be completely dead, but an open circuit secondary would arc across, and a few shorted turns would seriously degrade the spark.

[dsio]

Is it interchangable with the E34 coil? I have 2 525is here as well as the 318i so I can borrow parts to test if needed.

And how do you tell a worn distibutor cap (just out of interest).

Interesting that you mention the secondary could be arcing. I asked my electronics lecturer about that and he is the one that suggested that the coil couldnt be the problem, but what you say makes sense.

[Dan318-is]

if you have laods of fuel in the cylinders your timing mite be completely out

im not too good with this srot of thing but it seems youve eradciated any other problems.

[dsio]

I think the loads of fuel has more to do with how much this engine has been turned over by the starter with no ingition. It must still be full of fuel, but there isnt much I can do about that until I can ignite it.

What should I look for to see if the distributor is ok?

[Brianmoooore]

What should I look for to see if the distributor is ok?

Black tracking lines burnt into the surface, badly worn/burnt pins, and a damaged carbon button. Similar for the rotor arm, but it may have tracked right through to the metal spindlet it's mounted on.

[dsio]

OK, I have checked the resistance in the primary and secondary on the coil, and these are the results I got:

The primary resistance is around 1 ohm which is about right since the multimeter does not do decimals of ohms, and it should be 0.83 according to the haynes manual.

Here is the interesting part:

The resistance on the secondary is 5,300 Ohms

It says I should be getting 8,250 Ohms, so I am 3000 Ohms short on the secondary. Is that enough to cause the engine not to start?