Reminder: Check your ground straps

mrjimyjohn · 01-11-2025, 12:20 PM

Been chasing a sporadic misfire issue for weeks. One cylinder misfiring turned into 4 cylinders when i changed sparks and coils. Thought I had damaged the new coils going in.

Leaving my air filter cowl off overnight once allowed water in to fry my (recently replaced) blower motor and resistor.

Eventually decided to check ground straps and sure enough, the small engine ground near the exhaust manifold was hanging on by a thread.

CHECK YOUR GROUND STRAPS. Especially this one that can be accessed without removing anything else.

tsuintx · 01-12-2025, 09:31 AM

For sure. Especially if you live or the car has lived any considerable time in rust belt areas. Worth it for other areas too, of course.

lordnikon · 01-12-2025, 05:12 PM

The one in the engine bay is the interference suppression band. The one underneath the chassis is the ground strap. I believe it has a much thicker gauge wire.

jsunma · 01-13-2025, 08:03 PM

Quote:

Originally Posted by lordnikon

The one in the engine bay is the interference suppression band. The one underneath the chassis is the ground strap. I believe it has a much thicker gauge wire.

Exactly. The small one on the right side of the engine has nothing really to do with how the engine runs. Good to replace, but it can be removed and the car will still run.

The one you need to check is the large one that is below the starter. If that is weak or broken, you will get weak starts, misfires, and eventually once it pretty much entirely breaks a no-start situation.

Here are a few photos of mine as it was being replaced.

mrjimyjohn · 01-16-2025, 07:04 PM

Quote:

Originally Posted by jsunma

Exactly. The small one on the right side of the engine has nothing really to do with how the engine runs. Good to replace, but it can be removed and the car will still run.

The one you need to check is the large one that is below the starter. If that is weak or broken, you will get weak starts, misfires, and eventually once it pretty much entirely breaks a no-start situation.

Here are a few photos of mine as it was being replaced.

Thanks for the information guys, I’ll check that one too. I guess it was a coincidence that the interference band fixed my misfire because I have experienced some on subsequent starts.

e90yyc · 01-17-2025, 09:35 AM

Stay strapped 🔫

Bims328i · 01-17-2025, 11:31 PM

Now hit em' with the silicone spray every chance you get. Will add a layer of protection against corrosion.

lordnikon · 02-22-2025, 11:28 AM

Quote:

Originally Posted by jsunma

Exactly. The small one on the right side of the engine has nothing really to do with how the engine runs. Good to replace, but it can be removed and the car will still run.

I'm going to change the interference suppression band in the engine bay with a new one. Do you think it's necessary to disconnect the battery?

GoRomeo · 03-18-2026, 02:35 PM

Quote:

Originally Posted by lordnikon

I'm going to change the interference suppression band in the engine bay with a new one. Do you think it's necessary to disconnect the battery?

I hope you did. Its recommended.

My engine stalled yesterday on my E90. Very similar when I had loose ground nuts on the engine side. Haven't had any issues since then. It stalled using the AC and maybe this caused overload? Good thing I was on a stop light and started right up. I will check codes, but I know my ground strap looks old and greenish color. I am planning to replace it and see it this is the issue. Its over 20 yrs old.

https://www.amazon.com/gp/product/B0...YL93SJSD&psc=1

Anyone with same scenario?

jsunma · 03-18-2026, 04:16 PM

Quote:

Originally Posted by GoRomeo

I hope you did. Its recommended.

My engine stalled yesterday on my E90. Very similar when I had loose ground nuts on the engine side. Haven't had any issues since then. It stalled using the AC and maybe this caused overload? Good thing I was on a stop light and started right up. I will check codes, but I know my ground strap looks old and greenish color. I am planning to replace it and see it this is the issue. Its over 20 yrs old.

https://www.amazon.com/gp/product/B0...YL93SJSD&psc=1

Anyone with same scenario?

Again, I don't think that the interface suppression strap will make your car stall.

But on a related note, I'd have a hard time paying $45 for the BMW part when Amazon is showing compatible pieces for as little as $1 ($7 for 5). After all, these are simply braided wire with crushed connectors at each end.

GoRomeo · 03-18-2026, 05:11 PM

Quote:

Originally Posted by jsunma

Again, I don't think that the interface suppression strap will make your car stall.

But on a related note, I'd have a hard time paying $45 for the BMW part when Amazon is showing compatible pieces for as little as $1 ($7 for 5). After all, these are simply braided wire with crushed connectors at each end.

You may be right as it may not be the cause but I will replace it anyway. Its in very bad shape.

I know paying $45 its a little bit stiff but I am a strong believer in BMW genuine parts.

lordnikon · 03-19-2026, 10:00 AM

Quote:

Originally Posted by GoRomeo

I hope you did. Its recommended.

My engine stalled yesterday on my E90. Very similar when I had loose ground nuts on the engine side. Haven't had any issues since then. It stalled using the AC and maybe this caused overload? Good thing I was on a stop light and started right up. I will check codes, but I know my ground strap looks old and greenish color. I am planning to replace it and see it this is the issue. Its over 20 yrs old.

https://www.amazon.com/gp/product/B0...YL93SJSD&psc=1

Anyone with same scenario?

I could have used that information a year ago. lol...

Anyway I replaced both the ground cable underneath and the one in the engine bay.

Evil///M · 03-19-2026, 11:23 AM

This.
Been hunting down strange electrical ghosts for weeks now...I just ordered the upgraded Arc Terminal insulated one last week.

lowrydr310 · 03-19-2026, 11:37 AM

Quote:

Originally Posted by lordnikon

I'm going to change the interference suppression band in the engine bay with a new one. Do you think it's necessary to disconnect the battery?

Always good practice to disconnect the battery any time you're doing any work, even simple stuff like changing bulbs. However in this case it's absolutely not necessary to disconnect it.

GoRomeo · 03-19-2026, 02:42 PM

Quote:

Originally Posted by lordnikon

I could have used that information a year ago. lol...

Anyway I replaced both the ground cable underneath and the one in the engine bay.

What were the issues you were having?

lordnikon · 03-19-2026, 03:10 PM

Quote:

Originally Posted by GoRomeo

What were the issues you were having?

I didn't have any issues. I was replacing the starter so I also changed the ground cable, crank sensor, intake manifold gaskets at the same time.

The interference suppression band in the engine bay looked all oxidized so I just replaced that preventatively.

GoRomeo · 04-03-2026, 05:09 PM

Quote:

Originally Posted by lordnikon

I didn't have any issues. I was replacing the starter so I also changed the ground cable, crank sensor, intake manifold gaskets at the same time.

The interference suppression band in the engine bay looked all oxidized so I just replaced that preventatively.

I replaced mine today. I still had the factory one after 20 yrs.

01-11-2025, 12:20 PM	#1
mrjimyjohn Private First Class 56 Rep 117 Posts Drives: E92 328i xdrive Join Date: Nov 2021 Location: Toronto iTrader: (0)	Reminder: Check your ground straps Been chasing a sporadic misfire issue for weeks. One cylinder misfiring turned into 4 cylinders when i changed sparks and coils. Thought I had damaged the new coils going in. Leaving my air filter cowl off overnight once allowed water in to fry my (recently replaced) blower motor and resistor. Eventually decided to check ground straps and sure enough, the small engine ground near the exhaust manifold was hanging on by a thread. CHECK YOUR GROUND STRAPS. Especially this one that can be accessed without removing anything else. Attached Images
	Appreciate 4 StradaRedlands11295.00 tip_m28.50 tsuintx125.00 RealJ221596.50 Tweet Quote

01-12-2025, 09:31 AM	#2
tsuintx Private First Class 125 Rep 117 Posts Drives: 2008 328i Coupe, 2018 K1600GTL Join Date: Oct 2019 Location: DFW iTrader: (0)	For sure. Especially if you live or the car has lived any considerable time in rust belt areas. Worth it for other areas too, of course. __________________ 2008 328i Coupe 2018 BMW K1600GTL Plus some GM products...
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01-12-2025, 05:12 PM	#3
lordnikon Captain 842 Rep 870 Posts Drives: Break My Wallet Join Date: Feb 2023 Location: 416 iTrader: (0) Garage List 2011 BMW 328i xDrive [0.00]	The one in the engine bay is the interference suppression band. The one underneath the chassis is the ground strap. I believe it has a much thicker gauge wire.
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01-17-2025, 09:35 AM	#6
e90yyc Art Collector 2875 Rep 3,774 Posts Drives: 2007 328xi (GM-delete 6MT) Join Date: Feb 2018 Location: Canada iTrader: (0)	Stay strapped 🔫 __________________ When I'm dead, just throw me in the trash.
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01-17-2025, 11:31 PM	#7
Bims328i DIYer 576 Rep 561 Posts Drives: 2008 328i E90 SULEV Join Date: Jul 2020 Location: United States iTrader: (0)	Now hit em' with the silicone spray every chance you get. Will add a layer of protection against corrosion.
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03-19-2026, 11:23 AM	#13
Evil///M Professional Hitman 203 Rep 1,012 Posts Drives: Built 335is \| Ranger Tremor Join Date: Feb 2011 Location: 602 iTrader: (13) Garage List 2011 335is [9.17] 2021 Ford Ranger Tr ... [10.00] 2014 Audi R8 v10+ [10.00] 2019 BMW M2 Competi ... [9.75]	This. Been hunting down strange electrical ghosts for weeks now...I just ordered the upgraded Arc Terminal insulated one last week. __________________ Last edited by Evil///M; 03-19-2026 at 11:24 AM..
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