# E46 Spark Plug DIY



## FalconGuy (Sep 27, 2002)

Key thing is what is making the misfire? Plugs are rarely the cause. I would guess a coil for the cost and ease of swapping the coil to another cylinder and seeing if the fault follows the coil, why not give that a try first?


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## Dave 330i (Jan 4, 2002)

FalconGuy said:


> Key thing is what is making the misfire? Plugs are rarely the cause. I would guess a coil for the cost and ease of swapping the coil to another cylinder and seeing if the fault follows the coil, why not give that a try first?


Yep, I questioned the SA, and he said it was the plug. Of course he will run a test afterward replacing 6 plugs and then tell me it's the #2 coil, and charges me another $200? :yikes: I don't want to use my time to do diagnostics. Remember, it's hot here in Houston. And, I sweat like a hog. Anyway, the car runs fine now.


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## Dave 330i (Jan 4, 2002)

WAM said:


> Step 3
> Remove the 2 10mm nuts at the top left and bottom right of the coil. Plugs 1 & 6 have earthing straps.
> 
> Pull up the silver clip at the bottom of the coil with your fingers and gently ease out the connector. Now the coil can be lifted out.


yes, these were the pictures I was missing. Thanks. :thumbup:
You have to remove the plastic housing that goes over the oil filler to get to the coils?


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## Willby75 (Oct 9, 2007)

Great DYI thread and a real money saver. Just did my wife's 325xi which took about an hour and saved me 400 bucks. One thing I'd like to add is be very careful when removing the coil/boot from the plug. It's tempting to pull on the coil itself but DONT. Use constant, firm pressure and gingerly twist the boot while pulling. Also, when reinstalling it may be a bit disconcerting that you dont hear a "click" or "snap" when you put the boot back on but there's no need to worry......clean the micro-filter while your in there!


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## nabhan007 (Jul 22, 2007)

Just wanted to say thanks for the write-up!! Replaced the plugs in my '99 323i today, took about an hour, even for someone who has never replaced an engine part before (sad, I know). Dealer wanted CDN $150 just for the plugs! If I might add, the 100k rating on the OEM plugs seems very reasonable- I've got 144,000 km on the car (90,000 miles) and I've just started to have the occasional misfire/sputter while idling, but the car still runs fine most of the time. I'm sure I could have pushed an extra 5-10k out of them, but with a lot of traveling to do this winter, why risk being stranded in the middle of nowhere? Now I'll never have to worry about the plugs again for a very, very long time!


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## eengelbrecht (May 28, 2008)

:thumbup:


WAM said:


> Step 4
> Now using your spark plug socket with at least a 6" extension bar, you can remove the plugs and replace the new ones.
> 
> I used a high temp spark plug lubricant/ anti-seize compund so I tightened the plugs until just firmly tight. The spark plug torque is 30Nm otherwise.
> ...


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## CrazyNY (Feb 21, 2009)

I found this link on replacement coils with a pretty strong claim of improved performance (quoted below). Any input???

http://www.bavauto.com/shop.asp

"The core windings inside these coils have been modified to increase firepower and promote a faster, more efficient burn. This gives your BMW increased torque in the lower range of RPM and more horsepower in the upper range. Exact improvements depend on the current condition of your BMW's engine, but you'll definitely feel the difference. They'll also improve your fuel economy. Plus they come with new spark plug boots, making them an even better value. Installation is a simple, do-it-yourself procedure that takes about 30 minutes. Instructions included."


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## icmybmw007 (Jun 30, 2009)

*Need Help on my spark plugs*

I own a 2001 bmw 325i about two weeks ago i changed the spark plugs and boots on my bmw, however two week before that my car was running fine a little slow but fine untill i changed the spark plugs. So my question is do i have to calibrate the plugs? and if so, what tool do i need to get? I dont want to pay anybody.


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## Tyler5921 (Nov 8, 2007)

*I just did this...*

SO GREAT! I just did this. Took me about 1 hour 20 minutes. Thanks for the detailed instructions. The visuals made it so easy.

NOTE: it was difficult getting the coil out. but with pulling it came out. ALSO I don't think the spark plugs have EVER been changed. So initial loosening was difficult as well. the rest of it was EASY!

NOTE: when removing the plastic housing covers where the bolts are to remove the cover, be careful on the sloped cover when popping off the bolt covers. I dropped mine down the engine to the bottom. I was able to retrieve it. But be careful, maybe use two hands, one to hold the screwdriver, and one hand on the bolt cover to control it from popping off.

NOTE: I would also suggest starting with the furthest away from the front of the car. They are more difficult to get to, the easiest being the first three. Get the difficult ones out of the way first, then the rest are super easy.

NOTE: ALSO So as not to confuse which coil went in what hole, I did one complete change, then moved on to the next. So only one coil was out at a time. It broke up the monotony that way too.

Posting a pic of the SP that came out of the car. 2001 330 Cic with 39K miles. Bought 2 years ago at 11k miles. Don't think the SPs were ever changed, but you can let me know... I'll probably change them more often now that I know how to do it.

Thanks again for the great informative post. IF YOU HAVEN'T DONE IT, it is SO EASY to do... Just follow this post and you'll be fine.

Tyler


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## cardinal5 (Dec 8, 2009)

*How to tell which cylinder?*

Thanks to everyone who has posted to this thread. I'm going to attempt a coil swap tomorrow and feel reasonably secure I can handle it based on all the excellent information found here. My SES code indicated a mis-fire on cylinder # 1. I don't have a service manual and am not sure if # 1 is to the front or rear. Any information would be appreciated.

Cardinal5


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## bdonkersgoed (Jul 13, 2007)

cardinal5 said:


> I don't have a service manual and am not sure if # 1 is to the front or rear. Any information would be appreciated.


I would like to know this as well . . . does anyone know?

Thanks!


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## compusatman (Apr 14, 2010)

Thanks for the write up OP. And FalconGuy I am with you 100%. The only reason to pull the plugs early would be to apply some anti-seize on the threads. 100,000 miles are a long way to wait to find a seized plug. Even though it would be along shot. I have never had good fortune with Bosch plugs. NGK's on the other hand rock.


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## Fun MiLes (Jun 8, 2011)

I just swapped all my spark plugs. This post was helpful but a few things were not clear, in particular on the "pull up the silver clip" part. I ended up watching a youtube video and it all worked out!
Before the spark plug change, my car was running rough at idle (very rough on the last two days) and my service light had been on. As soon as I had put the last plug in, tied down everything, I tested it and it was running smoothly!
After 15 miles of driving and a few starts and stops, the service light is now off!
Very happy with this DIY job!

PS: I won't ever have to do this job on my 335d


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## bluebee (Mar 2, 2008)

Fun MiLes said:


> This post was helpful but a few things were not clear, in particular on the "pull up the silver clip" part. I ended up watching a youtube video and it all worked out!


I also tried to describe it and snap a picture of every step over here ...

- One user's pictorial DIY for replacing the BMW M54 engine spark plugs (1)


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## New61n (Nov 9, 2011)

Quick question. Recently had my 325CI major serviced (75,000KM) at a mechanic that service mainly BMW and Mercs. Part of that was changing the spark plugs, would that make the car be not as responsive when accelerating if you don't use the right spark plugs? I think it would, what are your thoughts?

Cheers.


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## Pursang (May 25, 2009)

alpinewhite325i said:


> Just used this DIY...excellent job.
> 
> Let me just add that after 53,xxx miles, my plugs had virtually no wear. I still replaced them with the OEM NGK's, however now I know I won't ever need to replace them again.
> 
> I believe they are truly 100,000 mile plugs.


The condition/performance of a sparkplug has somewhat to do with "wear".....but not JUST to do with "wear". AGE is another factor.....and you can't see age on a plug, except for maybe some discoloration on the outside and on the threads that hold it into the cylinder head.

Plugs DO wear out......in invisible ways......on the INSIDE where you can't see.

Toss them after two years, whether they "look" worn or not. They ARE! What's 30 or 40 bucks? You want performance, right? I knew you'd say YUP!


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## Pursang (May 25, 2009)

*!*



compusatman said:


> Thanks for the write up OP. And FalconGuy I am with you 100%. The only reason to pull the plugs early would be to apply some anti-seize on the threads. 100,000 miles are a long way to wait to find a seized plug. Even though it would be along shot. I have never had good fortune with Bosch plugs. NGK's on the other hand rock.


Oh, come on! NGK vs Bosch is like Mac vs Windows. That's so last Tuesday.

Move on.........and just change your plugs........to ANYTHING NEW!


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## Pursang (May 25, 2009)

New61n said:


> Quick question. Recently had my 325CI major serviced (75,000KM) at a mechanic that service mainly BMW and Mercs. Part of that was changing the spark plugs, would that make the car be not as responsive when accelerating if you don't use the right spark plugs? I think it would, what are your thoughts?
> 
> Cheers.


It COULD make a difference.......but not as much as probably your imagination! (kidding...but, sort of not). I personally always get a strange feeling that my car's performance/output has changed every time either I or anybody else does any work on it. Just drive it for a week and try not to think about it.

The type of gas you put in it will have a much greater affect on performance; load her up with a tank of high-test (Sunoco 260 if you have it) and watch/feel her go!


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## tm3kb (Jul 30, 2012)

*misinformation*

Not trying to be prick, but you mentioned something about the spreading of misinformation so I thought it would be appropriate to mention that the area has no relevance to breaking force. More area does not mean more friction. Friction only depends on normal force and friction coefficient, regardless of the area.



FalconGuy said:


> There is no bigger/better spark or more complete combustion, if there was the MFG would be all over it since more complete combustion would gain lower emissions, more HP and huge tax advantages for pennies per car, it either sparks or it doesn't, no science or data at all to support that 4 prongs are better than 1,2, or 3.
> 
> Not to thread crap but its just bad info that gets past around a lot. Kind of like vented/slotted rotors ( with less braking area thus less friction material and correspondingly less braking efficiency) will somehow give better performance. They dont, never have, never will. Its a simple equation, how much surface area do the pads have to contact, take any away and the performance goes down.
> 
> ...


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## Micster (Mar 8, 2010)

Stopped by today to find out which tools to loan my bro-in-law for tune-up of an '01 325i. Practically everything answered thanks to WAM's instructions. Thank you and well done! Technical writing isn't easy but you made it seem so. I guess it's a bad time to tell bro-in-law: NO TOOLS LOANED. (kidding sort of)


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