Simply Serviced: BMW 135i N54 Spark Plugs

"Jake Stumph Racing" (jakestumphracing)
12/31/2015 at 10:15 • Filed to: jakestumphracing, BMW, simply serviced

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Simply serviced is a series of mini-stories involving basic maintenance and upgrades. I am a weekend warrior, with no formal education on automobiles, who will try anything once (or twice). If I can do this stuff, so can you.

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In !!!error: Indecipherable SUB-paragraph formatting!!! the feedback was largely positive, and people wanted to see other routine maintenance items covered. With 5 years and 40,000 hard miles worth of service, most of which running substantially more power than stock, it was likely time to change the spark plugs on the BMW.

I first need to touch on something that pervades that turbo BMW community. Some people (read: vendors who sell parts) recommend changing plugs every 20k on tuned N5x motors. That is nonsense, OE plugs should be good for an easy 50,000 miles, even when the car is driven incredibly hard.

Like many other things regarding this car, this is another area where there is no sticker shock associated with BMW ownership. Plugs and coils are priced like they would be for any other car. I picked up 6 OE Bosch-BMW spark plugs from Amazon for $60 shipped.

Time to hit the garage, and get to it.

I run without the factory cowling, so that makes this a much more palatable service. The factory cowl covers the rear portion of the engine bay, obscuring the last two cylinders. If your car is all original, pop out the 10mm socket and screwdrivers and get to removing that.

15 minutes later, and you’re here. Welcome back!

Alright, at this point, we’re go need the following tools:

- E14 socket to remove the strut tower bars.

- 6mm hex for the engine cover.

- 3/8” ratchet and about 6-12” worth of extension.

- BMW N5x spark plug tool. Unfortunately unlike your typical Jap car, modern BMW’s do require this proprietary socket to grab the plugs. Fortunately, you can buy one new for ~$15, or in my case, be given one for free from someone who sold their car and no longer needed it.

That’s about it, so let’s get started.

Use your E14 (E-torx/reverse torx) bit and remove the strut tower bar from the passenger side tower, like so:

It impedes access to #5 and #6, so once this bolt is undone, it can be slid around and positioned out of the way.

From here, remove the plastic engine cover via the (4) 6mm hex bolts:

With the cover off, here is where we stand:

You can see why the strut tower bar needs to be swung out the way.

Moden BMW are coil on plug, so the coil packs need to be removed. Instead of using a bolt or fastener like most other cars, the coil wiring harnesses secure the coil down via plastic clips. This is a pretty ingenious packaging solution, if not a bit brittle/delicate. Check it out:

Open the clip up and disconnect the harness. From here, grab the “handle” and pull up to remove the ignition coil. Remember, this is thin plastic, don’t be a brute, it does not take much force to un-clip it, much like it does not take much force to break the clip. You’ve been warned. If this is your first time changing the plugs, or removing the coils, they might be a bit “stiff” and a bit tougher to remove. The coil is insulated with a rubber protector, so the rubber creates some stiction against the metal wall of the spark plug hole.

Coil #1 out:

With the coil out, we now have access to the plug:

Here is the spark plug tool that I used, it is the common Burger Tuning (BMS) unit, with about 12” worth of extension.

Hopefully you can figure out what to do from here: lefty-loosey and here we go.

Comparing the old and new. A bit sooty, which is not particularly surprising due to the tune, and occasional use of E85. Otherwise, the plug looks totally fine for 40,000 miles of faithful service.

I also took this time to quickly service the aftermarket oil catch can (OCC). There tends to be a bit of automotive ADD in the garage, so it made sense to hit this while I was thinking about it.

This is about 6 months and a half dozen track days worth of accumulation. It totaled about an ounce of oil blow-by. Glad to see my PCV system still looks healthy.

Back to the action, pop the clip (say that three times fast in front of your mother, if you dare), pull the coil and extract the plug. Things changed with cylinder two, and not for the better.

Oh here we go. The coil and plug were drenched. #3, #4 and #6 were all varying degrees of the same.

Crap. Looks like the valve cover or the gasket gave out and was soaking the tops of the cylinders with oil.

Not so simply serviced. The valve cover gasket is a bit tedious, but definitely doable. Before I began to order parts, I also thought “Hmm...when does the CPO warranty end on this car?” I knew we were right around the end of the warranty for the car, lo and behold, a month of warranty left. CPO deductible is $50 and they handle it. The price of parts, assuming it was just the valve cover gasket (and miscellaneous other one time use gaskets) would cost that much, no brainer.

I called the local modded car friendly dealership and they were able to get me in next day. I swap the old plugs back into the car, shelved the new plugs and reassembled everything in about 20 minutes.

Free loaner, and one day later, fixed. The service adviser confirmed that the valve cover gasket let go, they also took care of some other preventative stuff while everything was disassembled, thanks!

Maybe this wasn’t the best way to persuade folks that these cars are easy to work on. That said, it was my first time doing plugs on this car and all of this happened within the span of an hour. At least those plugs are still on the shelf for future use. So, next time on Simply Serviced , I may actually consider servicing something. Maybe.

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Jake Stumph is a weekend warrior autocrosser and track day bro. He spends his free time wearing his racing helmet and making vroom vroom noises. If you find his antics amusing or beneficial, then you can !!!error: Indecipherable SUB-paragraph formatting!!! , where he posts track-side updates and anecdotes.

Party-vi > Jake Stumph Racing 12/31/2015 at 10:15

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I did this to my E46 a couple days after I bought it, and used the wrong spark plugs. Days later at the shop (water pump/trans flush) they told me there was a misfire due to the wrong plugs being used. I felt like a fool.

Future next gen S2000 owner > Jake Stumph Racing 12/31/2015 at 10:15

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Something to add. Always check the gap. Make sure your spark plugs are gapped correctly, especially pre-gapped ones. Never trust a pre-gap plug. Sure they will probably work well enough but a couple bucks for the gapping tool and a couple minutes, it is time well spent.

Jake Stumph Racing > Future next gen S2000 owner 12/31/2015 at 10:15

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I was going to make a side note about that, but check out the plugs. OE N5x BMW plugs have three prongs and thus, gap doesnt need to be adjusted. :)

Burn-Spaz1966-Burn > Jake Stumph Racing 12/31/2015 at 10:15

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Flip Flops. Drop something on your feet and/ or unprotected legs.

Jake Stumph Racing > Burn-Spaz1966-Burn 12/31/2015 at 10:15

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If it works for this guy...

His Stigness > Jake Stumph Racing 12/31/2015 at 10:15

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Why the hell would you run without the factory cowling? That makes zero sense. Unless the idea of debris falling into the blower motor and hvac ducting sounds like a good idea. And having your ECU more exposed I guess go ahead.

Jake Stumph Racing > His Stigness 12/31/2015 at 10:15

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-15#, and more engine noise, that’s why. I have aftermarket filters covering the HVAC openings. DME box is still sealed in a plastic enclosure. Also, the cowling hinders access to things that I like to play with frequently, so keeping it off is convenient. Finally, I live in SoCal, this car hasn’t seen much in the way of rain, or weather.

Try actually interpreting all of the information in front of you before hopping on your high horse.

Thanks for playing. :)

His Stigness > Jake Stumph Racing 12/31/2015 at 10:15

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Don’t know what the hell “-15#” means, but to each his own.

Sure you’ve got easy quick access to the brake reservoir, but for me I wouldn’t want to give up the benefits of factory cabin air filters, and that plastic cover covering the DME doesn’t do shit, I know from personal experience rebuilding them. Having the cowl cover there does a good job of routing any water away from it, even in southern California. Just because it doesn’t rain often here you still have to worry about water from car washes, and rodents and shit if you ever park outside.

But you get back to your little maintenance jobs.

n54user > His Stigness 12/31/2015 at 10:15

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He meant it’s a 15-pound weight savings removed. Those aftermarket filters from BMS are plenty good, and the plastic ECU cover on the E8x/E9x seals out the elements completely. I’ve run without the cowl for years and have been through heavy storms and car washes, as well as dense dust winds without any issue at all.