MS880 - no spark with new coils

[Muddy42]

1 minute ago, Botty Cough said:

I'm still going with broken wire and most likely in the spark plug connector...🤺😬

3 replacement coils with broken wires? But maybe, easy to test.

[spudulike]

Strange...2 hrs use and this type of issue.

These big saws need a lot of conviction on starting and best to get the piston close to TDC before giving it the full lunge, any sign of a limp start and it will kick like a mule....Stihl could have done a better job on the low revs ignition advance.

On the coil to flywheel gap - set it to the very minimum gap and try testing for a spark then. This method can often get an intermittent coil of flywheel with poor magnets up and running again - worth a try although it may kick badly once the plug is back in.

The HT cap spur to coil laminate resistance check will either show no continuity or, I think from memory, around 1.2K Ohms....don't expect it to be near zero!

[Mark_Skyland]

If its new as in its been purchased within the last 12 months then it should be covered under warranty. I know the 880 has been out of production for quite a while but it doesn't matter if it was purchased recently from a dealer.

Its a strange one as coils very rarely fail and I would be surprised if a new OEM one was faulty from the start. If the flywheel magnets are good and they almost never fail then it must be a bad coil if the cylinder has continuity to the coil mounts, although I don't see how that is possible tbh.

Not many people have a spare 880 to hand but if someone you know does, this is the time to ask for a favour. Swap the parts out until you find out which one is not working

 

It looks like the 880 has a couple of options as they have changed the coil and flywheel so its possible that you dont have a matching pair. But, if it fits then I would at least expect a spark.

 

 

[Bob Murphy]

Well, I have tested for continuity between the plug cap and the coil laminations - no connection. I then did the same test on the MS461 (which has a spark and kicks like a mule) - same result, no connection. 

I am using the 'buzzer' test on my multimeter, maybe I should be testing the resistance instead, I'll need to read the instruction manual for the meter!

The MS880's flywheel is alloy, with two sets of magnets 180 degrees apart. I bought a Chinese replacement that was identical - right down to the small print disclaimers cast into it. That didn't change anything so I don't think its lack of magnetism.

 

Yes I have tried different spark plugs - both of the same make and number and brand new ones that are totally wrong for the saw, just in case - no spark.

 

I have set the coil-to-flywheel gap to 0.015" on both the 880 and the 461. I'll try and start them both today (I don't like running big chainsaws on a Sunday - I do have neighbours). I'll report back.

 

The working coil on the 461 is totally different to that on the 880, it has three mounting setscrews whereas the 880s has two, The 461 coil is also considerably larger than the one on the 880. I am therefore unable to swap them.

 

On the other hand I now have two Stihl coils and four Chinese coils for the 880. I have had a couple of weak sparks from the Chinese coils but nothing recently from the original Stihl coil or the new (ridiculously expensive @ £222.06) Stihl coil.

 

Its not a 'broken wire' as everything is disconnected. I just have a coil, a flywheel and a spark plug !  

 

The investigation continues, thanks for your input. 

 

Bob.

   

[Muddy42]

Weird, are you sure you're doing the test right?  The working 461 should show continuity.  If not, this would mean the coil is not connected to the plug, electricity cannot travel so no spark even if the coil and flywheel are good.  In my basic mind, you need an electrical loop - a surge of electricity travels up the ignition wire, through the middle of the spark plug, sparks across the gap, back along the outside of the spark plug and back through the case.  A failure of any part of this loop and no spark, so test as much as you can.

 

[roys]

Think the issue re the continuity test is, as hinted at, that you did it on the buzzer which would not buzz at the expected 1200 ohms, it will have to be tested with the meter on the Ohms range and not the continuity buzzer.

[GarethM]

Swallow your pride and take it to a dealer.

[Muddy42]

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Edited March 4 by Muddy42

[roys]

1 hour ago, Muddy42 said:

or keep it simple.

 

Won’t work as he is needing to measure about 1200 ohms, needs to use a multimeter set to resistance (ohms)

[GarethM]

8 minutes ago, roys said:

Won’t work as he is needing to measure about 1200 ohms, needs to use a multimeter set to resistance (ohms)

Bulb probably won't even illuminate at 1200 ohms, or just blow it after going through the windings.