2015 GLK 350 51k - Injector coil 4 misfiring - replace one or all? Possible cause?
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From: NJ
2015 GLK350
2015 GLK 350 51k - ignition coil 4 misfiring - replace one or all? Possible cause?
I have a 2015 GLK 350 and it has 51,000 miles on it.
My engine light came on 7 months ago and engine would shake when idling at times, can't accelerate well. Turn off the car and restart and sometimes it works fine. Sometimes engine light disappears and car works fine for several days. Then it will start up again.
local mechanic hooked up the diagnosis machine and it discovered that the #4 injector coil is malfunctioning. Sometimes the engine light turns off and the car functions properly.
Don't know if its coincidence, but this problem started right after I added an engine cleaner… thinking I was helping my car.
Red Line 60103 SI-1 Complete Fuel System Cleaner
(which I researched as having the highest percentage of PEA for cleaning fuel systems.)
Question:
1) Should I pre-emptively have them replace all the ignition coils? Or just have them replace #4? (mechanic explained even if I'm going through 3rd party insurance, it would cost extra labor to access the other 3 injector coils on the other side.)
2) Also, should I pre-emptively have them replace all the spark plugs too? Waste of money at 51k?
I keep reading different things and would like some advice.
3) Did the fuel system cleaner cause this problem? Was this the catalyst? Or just coincidence? Car was running fine until after I added that cleaner.
4) always go with OEM?
Thanks for your help and advice!
My engine light came on 7 months ago and engine would shake when idling at times, can't accelerate well. Turn off the car and restart and sometimes it works fine. Sometimes engine light disappears and car works fine for several days. Then it will start up again.
local mechanic hooked up the diagnosis machine and it discovered that the #4 injector coil is malfunctioning. Sometimes the engine light turns off and the car functions properly.
Don't know if its coincidence, but this problem started right after I added an engine cleaner… thinking I was helping my car.
Red Line 60103 SI-1 Complete Fuel System Cleaner
(which I researched as having the highest percentage of PEA for cleaning fuel systems.)
Question:
1) Should I pre-emptively have them replace all the ignition coils? Or just have them replace #4? (mechanic explained even if I'm going through 3rd party insurance, it would cost extra labor to access the other 3 injector coils on the other side.)
2) Also, should I pre-emptively have them replace all the spark plugs too? Waste of money at 51k?
I keep reading different things and would like some advice.
3) Did the fuel system cleaner cause this problem? Was this the catalyst? Or just coincidence? Car was running fine until after I added that cleaner.
4) always go with OEM?
Thanks for your help and advice!
Last edited by JediMindSheet; Feb 5, 2025 at 01:00 PM. Reason: More details and questions
Senior Member
Joined: Feb 2020
Posts: 490
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From: Lac Ste. Marie, Quebec
2006 Alfa Romeo Brera, 2010 GLK350, 2018 BMW 640i GT, 1997 Subaru SVX, 2012 Moto Guzzi Norge GT8V
Injector coil? It's either a fuel injector or an ignition coil. If it's intermittent, it's likely an ignition coil. At that mileage just replace the one (OEM) and no spark plugs.
A fuel injector problem could be caused by using cleaner but the problem would be constant.
A fuel injector problem could be caused by using cleaner but the problem would be constant.
Last edited by Silver Shadow; Feb 5, 2025 at 07:08 AM.
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Mercedenz
Hi, Just perform regularly your Preventive maintenance such as Change your Air filter, Fuel Filterm, Spark Plugs if you did not replace any of things the result was misfiring
misfiring cause the inoperative ignition coil? Yes! due to inoperative spark plug? YES!
The common advice was to replace all ignition coil and fuel injectors if misfiring occur duting scanning.
misfiring cause the inoperative ignition coil? Yes! due to inoperative spark plug? YES!
The common advice was to replace all ignition coil and fuel injectors if misfiring occur duting scanning.
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Joined: Sep 2015
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2013 glk 350
What part did the mechanic say it was ? Injector is fuel system , the Coil is electric spark. You said “injector coil” they are two different parts of two completely separate different systems. But both can basically cause the same issues. You should order the part yourself from FCP euro and get a quality part with lifetime warranty Fcp offers. You don’t want your local auto store Chinese part. I would just replace the one bad part. Spark plugs last 100,000 miles unless your motor has issues with the cilinder . I would not replace all plugs but have mechanic look at that one spark plug to see its condition . A lot can be learned about a motors health from “reading” plug condition compared to a photo of a “ spark plugs condition “. Which will have a chart of maybe 15 photos of different plugs conditions.
Last edited by Mmr1; Feb 5, 2025 at 07:32 AM.
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Electrical fuel injectors can also have coils. Many do. They just happen to be internal to the injector body.
Last edited by MBKLUE; Feb 5, 2025 at 09:26 AM.
Senior Member
Joined: Feb 2020
Posts: 490
Likes: 150
From: Lac Ste. Marie, Quebec
2006 Alfa Romeo Brera, 2010 GLK350, 2018 BMW 640i GT, 1997 Subaru SVX, 2012 Moto Guzzi Norge GT8V
In my whole life (65+ years), I've only replaced 2 ignition coils. I have a '97 Subaru SVX with 300,000 km with original coils.
Last edited by Silver Shadow; Feb 5, 2025 at 02:13 PM.
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2021 GLB250 FWD, 2023 GLA250 FWD, 2013 C250, 2015 GLK350, 2005 ML350SE, 2003 E320
Do not replace spark plugs because that is not a simple job on that engine.
The injector cleaner didn’t cause this issue.
You don’t need a Mercedes branded part (FCP “genuine”) but stick with Bosch or Beru which Mercedes uses (FCP “OE”). I prefer Bosch.
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