N52 spark plug and coil change how to

[groovy_hippy]

Hi folks, there's probably a load of articles on how to do this, but though I'd share my experiences...

I have a 2007 N52 2.5i Z4 - it was having a few hiccups on acceleration at sub 2k revs. The job came in under £150.

1) Replaced all 6x coils with Bosch 0-221-504-470 - these are the revised version of what was in the car before (Bosch 0-221-504-467) according to Bosch's website. At the time of writing these are only about £17 each on Amazon - grab a bargain folks!
2) Replaced all 6x spark plugs with NGK iridium ILZFR6D11 - from CarParts4Less with one of their discounts, came in at just over £9 each.


Tools you'll need:
6mm hex head for removing the plastic engine cover (might be 4 or 8, but if you've got a set you'll be fine)
M10 spark plug socket and ratchet
Torque wrench
A tea towel/rag, and some olive oil or such (I'll come to that bit
Something to gap the plugs with (pliers and hammer) and a feeler gauge. Google how to do this, and if you wreck your plugs don't blame me ;-)

1) Whip off the plastic engine cover. You don't need to remove the cross brace
2) Unclip each plug that goes into each coil. Pull the plug out of the coil and get it clear of the coil.

3) Now for the tea towel or rag - hook it through the plastic clip and pull. Give the coil a roundabout wiggle if you fancy. They're quite hard to pull out but will come eventually with a champagne cork like pop. Repeat for all coils.


4) Check there's no rubbish lying around in the bottom of the holes and undo the spark plugs, one at a time. Mine were quite tough but nothing too bad. Install each new plug after whipping out the old one, finger tight at this stage. You don't want to leave holes open into the cylinders for longer than you have to.

5) Once all the new plugs are in, torque them up to 23 Nm +/- 3 Nm (in the BMW service manual).
6) Push the new coils into place - I started at cylinder 6 (near the bulkhead). They'll push into place with a small 'bump'. I found cylinder 4 to be the most tricky - it's next to the motor that looks after the variable valve timing (I think). Put a smidge of olive oil on the side of the motor to help the rubber coil slide past it if you're having trouble ;-)

Put the plugs back in - push them as far as they'll go and then put the clip down (watch your fingers, they can bite!). Repeat for all coils. Get the plugs all the way in or you'll get a misfire (I did, ha!). Don't leave any 'gap' at the 'top'/towards passenger side, of the 'oval shape' hole in the top of the clip.

7) Clear your tools up and fire it up - should be running happily! If you have an OBDII reader or Carly, perform a reset so the computer can re-learn the new coils and spark plugs.
8 ) Put the plastic engine cover back on and have a cuppa before taking it out for a spin!

 

[Ducklakeview]

Nice write up Jess, has it cured your problems?

Mike

 

[groovy_hippy]

Seems to have done Mike - certainly a bit snappier on acceleration now! I'll give it a few more trips before I'll know for sure. But, judging by the amount of cr@p on the electrodes on the spark plugs, and the corrosion on the coils it can't have made it any worse ha!!

 

[Buckz]

Nice write up Jess, has it cured your problems?

Mike

would like to know too As I sometimes experience a bit of weirdness low rpm..

 

[groovy_hippy]

I should also add that I gapped the plugs to 1.1mm as it says on the NGK website. I found a post on a US forum that said the imperial equivalent too, so that was good enough for me!

 

[Steve84N]

It's the valvetronic motor that controls valve lift not timing. Basically it acts instead of a butterfly throttle body.

 

[Ducklakeview]

It's the valvetronic motor that controls valve lift not timing. Basically it acts instead of a butterfly throttle body.

Erm, no it doesn't..

Mike

 

[GuidoK]

Do you have pictures of what your sparkplugs look like (soot or coffee brown etc)

It's the valvetronic motor that controls valve lift not timing. Basically it acts instead of a butterfly throttle body.

I think so too.

 

[Steve84N]

It's the valvetronic motor that controls valve lift not timing. Basically it acts instead of a butterfly throttle body.

Erm, no it doesn't..

Mike

Care to elaborate as erm, yes it does...

The VANOS does the timing and the valvetronic motor mentioned in the guide controls lift through the use of an extra eccentric cam as explained here: http://www.bmwblog.com/2016/07/25/valvetronic-bmws-innovative-throttle-system/

 

[groovy_hippy]

Well, whatever that motor has to do with valves, we're talking spark plugs and coils folks ;-) ....and here's the pictures of what I removed yesterday...

Mucky spark plug next to new one...


Old coil - the new ones were bright silver inside but I didn't get a picture.....

 

[RyanB88]

Nice write up, thanks!

 

[Ducklakeview]

It's the valvetronic motor that controls valve lift not timing. Basically it acts instead of a butterfly throttle body.

Erm, no it doesn't..

Mike

Care to elaborate as erm, yes it does...

The VANOS does the timing and the valvetronic motor mentioned in the guide controls lift through the use of an extra eccentric cam as explained here: http://www.bmwblog.com/2016/07/25/valvetronic-bmws-innovative-throttle-system/

Yes, the valvetronic controls the lift of the inlet valves, but it doesn't act like or simulate a butterfly throttle valve.

In other words, in normal driving, the “gas pedal” controls the Valvetronic hardware rather than the throttle plate.

Mike

 

[Ducklakeview]

Erm, no it doesn't..

Mike

Care to elaborate as erm, yes it does...

The VANOS does the timing and the valvetronic motor mentioned in the guide controls lift through the use of an extra eccentric cam as explained here: http://www.bmwblog.com/2016/07/25/valvetronic-bmws-innovative-throttle-system/

Yes, the valvetronic controls the lift of the inlet valves, but it doesn't act like or simulate a butterfly throttle valve, the engine still has a butterfly throttle plate.

In other words, in normal driving, the “gas pedal” controls the Valvetronic hardware rather than the throttle plate.

Mike

 

[Steve84N]

You misunderstood me, whilst it doesn't actuate a butterfly valve it does the same job as one in that it regulates air intake.

The butterfly throttle plate is purely there as a back up but unless something goes wrong the valve is always wide open. In other words it's not regulating air intake, the valvetronic motor is.

The downside of a throttle valve is high pumping losses at small openings. By having atmospheric pressure right up to the inlet valves this problem is removed. Then when you want a small amount of power valvetronic opens the valves with just a small amount of lift letting only a small amount of air in. The upside is it's not sucking through a straw so to speak. The efficiency benefits of valvetronic diminish with larger throttle applications and actually it becomes less efficient at very high revs due to the stiffer valve springs required.

Given that the valvetronic motor acts on the eccentric cam that adjusts valve lift that controls air intake the motor is acting instead of a butterfly valve and performing the same role.

 

[jack07]

Good 'how to ' Groovy.I would mention a good precautionary dab of anti seize compound on the new plug threads to help with future removal and avoid pulling thread material from the cylinder head at next change.

 

[maxman]

Very good write up.

 

[groovy_hippy]

Good 'how to ' Groovy.I would mention a good precautionary dab of anti seize compound on the new plug threads to help with future removal and avoid pulling thread material from the cylinder head at next change.

The use of anti-seize compound seems to be up for debate - the BMW workshop manuals don't say use it, but then other places do say use it...I didn't (neither my or my other half have even used it on our cars), but I'm not going to criticise someone who does use it. It's a bit like buttering your toast if you're having jam on it if you ask me ;-)

 

[MACK]

You misunderstood me, whilst it doesn't actuate a butterfly valve it does the same job as one in that it regulates air intake.

The butterfly throttle plate is purely there as a back up but unless something goes wrong the valve is always wide open. In other words it's not regulating air intake, the valvetronic motor is.

The downside of a throttle valve is high pumping losses at small openings. By having atmospheric pressure right up to the inlet valves this problem is removed. Then when you want a small amount of power valvetronic opens the valves with just a small amount of lift letting only a small amount of air in. The upside is it's not sucking through a straw so to speak. The efficiency benefits of valvetronic diminish with larger throttle applications and actually it becomes less efficient at very high revs due to the stiffer valve springs required.

Given that the valvetronic motor acts on the eccentric cam that adjusts valve lift that controls air intake the motor is acting instead of a butterfly valve and performing the same role.

+1 great explanation above. The fact it has a back up butterfly valve seems to often cause confusion/ catch people out.

 

[GuidoK]

You misunderstood me, whilst it doesn't actuate a butterfly valve it does the same job as one in that it regulates air intake.

Exactly, both the butterfly valve (throttle body) on a normal car and the valvetronic system on this engine serve that same purpose.
It is the essence of valvetronic.

The n52 has an extra butterfly valve afaik to regulate the esp system (just as for instance some m52 engines have dual throttle bodies, one cable operated for throttle, one electronic for esp/act) and I'm not sure but I think its a mandatory european safety construction in that its automatically shut when the system loses power (at least thats what I got at some point for explaining why all electronic throttle bodies are spring loaded). If the valvetronic motor would loose power, I think it would stay in its position it was last in and not automatically close the valves.

Mucky spark plug next to new one...
IMG_8431.JPG

I know they're different type/brand sparkplugs, but does it seem that from the old one the tip has melted away a bit? (have you measured the gap to see if its different?)
Or maybe the new one just has a longer point on the tip.

 

[Steve84N]

I thought it was normal to see the tip wear down slightly and that's one of the reasons why they need replacing?