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Dead Stihl 362 Mtronic

thomasinvancouver

thomasinvancouver

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I was cutting some firewood at the beach. Saw was running perfect as normal and then just up and quit. Gas has been in it for a while, but it’s good non-ethanol with Stihl oil. It was running long enough that it wasn’t just the bowl emptying before it died. I pulled the plug and grounded it out on the cylinder and pulled the starter. No spark. I’ve already ordered a new coil, wire, and plug. Plug is fine, but what the hell, I’ll replace it too. Is there any reason I can’t just swap it out? Is my troubleshooting and solution sound? Anything else to check?
 
jltrent

jltrent

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From my experience coils on these newer saws just don't last like they use to and they are pricey. If the same coil I don't see a problem swapping.
 
NIP Group
DND 9000

DND 9000

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Don`t ground the plug on the cylinder for spark testing. This can destroy the control unit. For spark testing use a ignition spark tester. First if you have a no spark condition, check the wires, switch and cable connections. If somewhere is a short circuit or broken cable, the control unit will give no spark. The conection between the control unit, trigger unit and solenoid valve must not be damaged, otherwise you`ll have no spark. Also make sure that the magnets on the flywheel are in good condition and that the air gap between the control unit and flywheel has it`s basic setting.
 
stihl86

stihl86

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You should have just unplugged all connections and plugged them back in.
As DND said in regard to testing, you need an inline tester.
Sometimes, when there is a connection problem, the test will show spark once
and once only.
 
Wood Doctor

Wood Doctor

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You cannot check for a spark the typical way on a 362 M-tronic. Once that plug is removed, the circuit detects it and disables the spark. From the service manual:
"Testing in the workshop is limited to a spark test. A new ignition module must be installed if no ignition spark is obtained (after checking that wiring and stop switch are in good condition)."
 
DND 9000

DND 9000

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Yes it is grounded. I mean if you test for spark and want to see the spark with the plug removed from the cylinder.
 
Goofaroo

Goofaroo

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So what's the difference between plug screwed in (running) and holding against fin to check for spark?
Also confused.
It doesn’t make any sense. These saws are disposable in my opinion. They’re just like newer cars. Too complex to be worth restoring.
 
frank_

frank_

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they have 2 pole shoes dont they ?
praps the ecu uses the tdc and bdc magnets to diagnose the power stroke vs upstroke (time difference) to access the fuel quality etc ?
cars ecu,s to compare the crank sensor pulses to determine which cylinder is misfiring or whatever
so the m tronic may spark in initial startup mode , and then flag a nospark if the conditions are wrong ?
 
DND 9000

DND 9000

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I have an early 441c does it also apply to this saw?
I don`t know exactly, but should be valid for every m-tronic model.

so the m tronic may spark in initial startup mode , and then flag a nospark if the conditions are wrong ?
I talked with a mechanic in the past about this and he said, that it can give 2 or 3 sec. spark that you know the control unit is working and if a malfunctioning connection (cables etc.) is present spark is shut down.
 
stihl86

stihl86

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Does th M/T know the plug is not IN cylinder?
Yes. It‘s a very smart system LOL Actually I agree with DND. They want a positive ground path for the discharge.
TBH, I’ve never heard what exactly it damages, but have been told it can damage the system.
And it really sucks to do more damage when you’re trying to repair something.
So I don’t chance it.
 
thomasinvancouver

thomasinvancouver

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The new coil and plug showed up today. Unfortunately they’re the wrong ones. I’m guessing newer 362CM saws use the smaller spark plug so what I received was the smaller plug and a pre wired coil that only fits the smaller plug. Still not sure if my diagnosis is correct, but I checked out the wiring and didn’t find any thing wrong.
 
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