Lots of recommendations to replace the coils when doing spark plug change on aging BMWs and other cars. I've never replaced coils unless they failed except to upgrade, but I decided to this time. Several things to verify to order the correct coils and I'm confident I got the correct ones. First start with new plugs and coils and it sounded like it was running on 4 of 6 cylinders, but maybe it was only misfiring on 1. I quickly installed the old coils and it runs perfect.

I compared the new coils with an ohmmeter and none stand out as blatantly bad. I bought the replacements from RockAuto, so returning them would be a pain, plus probably costly with restock fee and shipping. I doubt I had a bad connection to any of the coils because of the way the wires plug into the coils seems quite sure. I suppose I will reinstall the new coil set and see how it runs.

Any ideas on how to proceed? Thanks

I think the spark plugs are to be changed at 100K miles, I did them at 75K and several showed some evidence of electrode wear, one in particular. The ones that I replaced were NGK double platinum and I'd say they probably should have been replaced at about 60K. It is running better and starting better with the NGK Ruthenium plugs I installed.

Anything show up from your OBDII tool?

I replaced on my 04 and my 05 Nissan once I started having codes thrown.

Since you have verified the coils as good, it almost sounds like you may have had something as simple as a connection issue on the initial installation of the new parts.

quote:

Originally posted by smschulz:
Anything show up from your OBDII tool?

I replaced on my 04 and my 05 Nissan once I started having codes thrown.

I didn't let it run poorly long enough to trip a code. I shut it off and installed old coils.

Are they Bosch?

Get Bosch

quote:

Originally posted by 83v45magna:
Are they Bosch?

Yes, as are the originals that lasted 140K and 19 years.

Maybe one at a time?

One thing is certain, the ones you got are shite. I'm wondering about chinese knock offs.

I would at least contact Rock Auto with the facts you list above. See what they offer (if anything). If they tell you to pound sand, then they fooled you, once.

I wouldn't let it happen again.

quote:

I compared the new coils with an ohmmeter and none stand out as blatantly bad.

That only tells you their internal resistance, not that they actually work. This is like manually cycling rounds through your gun & magazine - it tells you little or nothing; only actually shooting the gun does. Remember that an ignition coil steps 12 volts up to 30-50,000, hundreds of times a minute, without even a means to shed heat. N-E-W doesn't always spell G-O-O-D. Sometimes it stands for Never Ever Worked.

This message has been edited. Last edited by: egregore, May 08, 2025 11:35 AM

FCP euro for bmw parts.
I wouldn't buy plugs or coils from rockauto.

https://www.fcpeuro.com/

.

quote:

Originally posted by Greymann:
FCP euro for bmw parts.
I wouldn't buy plugs or coils from rockauto.

https://www.fcpeuro.com/

.

Why?

quote:

Originally posted by Georgeair:
Maybe one at a time?

Good idea

Why I won't buy from rockauto is because of counterfeit parts from China.

5-series have a straight-six engine with coils right on top, correct? (This is their best engine, BTW.) Swap one old for new coil at a time in the most accessible cylinder. The one that misses is the bad one. For further verification, lay the coil on top of the engine, wire connected, run the engine and use a grounding probe (alligator clip lead fastened to an insulated-handle screwdriver or long pick) to check your spark. A good coil will easily make a spark half an inch or more past its end. If you see a little puny one or nothing at all, there you go.

quote:

5-series have a straight-six engine with coils right on top, correct?

Those were awesome.
The car in my avatar has an engine install similar to a size 12 in a size 7 shoe. Getting to the rear two is a specific combo of extensions, prayer and cussing.

Recently had plugs replaced while shop was replacing rod bearings (a needed maintenance item from new due to design flaw). I deferred just replacing all coil packs due to cost.

I’ll probably come to regret this….

I raced an earlier BMW (e36), and our family has owned a number of them over the years that I've maintained. Dead new coils are common, and it's best to buy from reputable vendors to avoid the chinesium.

Bimmerworld and FCP Euro are good vendors, and will stand behind their products. Both supported my (and other) racing class. Bimmerworld has staff you can actually call and discuss your problem with before they will suggest a solution.

https://www.bimmerworld.com/En...ackage-M54-Late.html

BUT - if the original coils are still working, run them until they fail? We kept the original coils in the race car past 200k miles.

You should replace the coils one at a time, see if/when the problem returns, it could be one bad coil, or, one that wasn't correctly installed.

Doing it this way you have only one item at a time to detect the issue.

It's possible one is bad, but likely it's a connector, check each one inside to be sure it's clean and ready to go.

BTW as far as counterfeit and RA, they don't buy wholesale and inventory, warehouse and ship.

RA does aggregate or create a digital marketplace with an easy to find parts search system. The orders are sent to over 100 independent warehouses in the USA, that stock parts, including OEM parts in some cases.

Many parts made today are from China for both aftermarket and OEM, so the assertion that RA is selling counterfeit parts isn't correct, you're more likely to get a counterfeit on Amazon, where they police nothing, and allow anyone to market parts, sell their inventory and close shop.

Now could a part get into the supply chain being sold to a warehouse, sure, but that could happen on Amazon or a local auto parts store.

^^ Just another reason to buy from FCP Euro!

In the process of replacing one at a time and starting it, first two went perfect. Found the problem on the third. The coil didn't stay in spark plug well, it kept moving out. I took a spark plug and plugged into one of the old coils and one of the new ones and the original clipped onto the spark plug terminal with a snap or click, the new ones don't. The new coils rely on the rubber rings that ride on the top of the plug well to keep the coils in the head, an unsure system that doesn't work on my car. Now to see how merciful RA is about it.

The replacement Bosch coils are made in Slovenia.