unstable coil pack readings

bass84

so I have a misfire on one cylinder. the spark plug is not firing including the brand new plug, ive tested resistance on the coil but im getting an unstable reading. the readings range from 0.1 ohms to 0.9 ohms n never stable on both tested pins. Im 100% that the probes from the voltmeter were nicely contacting the pins.

Has anyone come across these readings?

evocarlos

did you try it with the coil pack removed from the head ?
try the 200ohm setting on your meter
i will go and get me spair and check if its the same 🙂
brb

Matt

https://z22se.co.uk/threads/eml-spanner-light-now-car-wont-start.23541/#post-1203151

Have you tested it outside of the block to see if there is spark being generated?

evocarlos

stable readings of .6 from both coils on my spare using a cheapo meter set to 200ohm

bass84

My dad is sparky n just used his exspensive tester. It's auto rangeing. I got 0.17 across both this time.

No I haven't taken it out n tested. Do you mean take the pack n plug off but leave connected n turn the engine?

Matt

IDI AMIN said:
To test the coil pack remove it from head but without disconnecting plug. you turn key and hold a piece of metal to each spark plug one at a time if theres a spark you know its okay if not you know there is a problem
From my experience there is no spanner or engine light for a dodgy coil pack and it should still start but idle very roughly. i think you have some other problem that is unrelated to your coil pack but it is worth testing coil pack anyway

bass84

I have no eml lighting up. It's just one spark plug. Second from the right. There is fuel going through as I can smell it unburnt. n when the spark plug is out you can tell it isn't igniting, it's just black. I'll try that test tomorrow with a bit of small cable.

evocarlos

bass84 said:
My dad is sparky n just used his exspensive tester. It's auto rangeing. I got 0.17 across both this time.

No I haven't taken it out n tested. Do you mean take the pack n plug off but leave connected n turn the engine?

i tested this one off the car and unplugged if you get 0.6 on both coils then the coils are fine the regulator on top will need testing as in that vid test light to see if you get output

bass84

The unstable results were due to faulty meter. But still don't understand the fancey auto rangeing meter showing 0.17 on both

bass84

Thanks for your help guys. Wish I new someone round here that would lend me the pack n module. been to scrappies n nothin in at all. Think I'm just gonna have to buy the pack n module. If it doesn't fix it I can just sell it on I suppose.

If I can get a helper I'll try the out of block test n module test tomorrow

Cheers peeps

bass84

I seem to be getting a spark when I do the test with the pack out of the block. I jumped from plug to pin using some cable n I get a tiny spark on all plugs. I've got a coil pack n module coming to try still but any ideas on what else it can be?
I changed the timing chain a few months ago but don't think it will be that as I only have one dirty spark plug.

Matt

Any chance you can take a photo of the dirty spark plug?

bass84

Yeh can do in a little while. It's just black soot

bass84

Here's the dirty one

bass84

ive also just noticed the car is fine when de-accelerating, when I changed down gear towards a corner I purposely changed a little soon to do some engine braking and the car purred just fine. don't know if that means something?!

MikeS

you done a compression test ?

bass84

No mate. I'm gonna speak to the mechanic across the road n see if he has his gauge still. I did it when I changed the chain n all was fine

bass84

It's definitely not the coil pack. I'm going to do a compression test asap. Any ideas on the only other reasons for a single misfire??

Are the only other possibilities valves or injector?

I don't think it's a blocked injector because I can smell fuel when sat still and there is no leak

bass84

So I've just been reading, I read that over fueling can cause the dry soot to collect on the spark plug, is that right? So this means I could have an over fuelling problem?

I also read that an oily soot is the piston ring?!

MikeS

Was the spark plug dry or wet obviously excluding petrol