[suspenceful]

Before I start heavily modifying my BMW 335i, I'm focusing on maintenance. This week I changed the spark plugs and ignition coils and wanted to shed some light on the process. I filmed an in-depth video and wrote a guide to help others properly replace, gap and install their new plugs & coils.

As you begin to modify or maintain your BMW 135i, 335i or 535i, you must address the ignition system. Spark plugs and ignition coils are the achilles heel of the N54. These two parts are common sources of misfires if not taken care of. Not only is it important to replace them with upgraded pieces, but it’s crucial to install the spark plugs with the correct gap.

Ultimate N54 Spark Plug Guide: https://bmw335i.com/2019/05/22/bmw-n...ent-gap-guide/

I even used my Dragy to get some real-life performance results before and after swapping the plugs & coils!



I guarantee if you watch the video or read my complete blog post, you'll learn something that you didn't know before. I'm a fellow enthusiast, so please let me know what you think

[N54Society]

Nice post. Looks like you shaved some time off of the same run. Thanks for sharing.

[Fuel-It!]

Nice guide!

[type-dRew]

The gains are likely even higher, because that 1-2 shift on the 'after' run was HORRENDOUS compared to the pre plug swap run.

Great write up and video, sub'd on youtube now.

[type-dRew]

Also, those gap tools have existed for quite some time. BMS is just selling them with their name on it, not an original product.

I use the torque solutions unit;

https://www.maperformance.com/produc...iABEgIpvPD_BwE

[TheMidnightNarwhal]

"Not only is it important to replace them with upgraded pieces, but it’s crucial to install the spark plugs with the correct gap."

I am FBO and can run Stage2+ E30 with factory Bosch plugs and coils no issues

Am I going to start getting misfires prematurely as they age?

[type-dRew]

Originally Posted by TheMidnightNarwhal

"Not only is it important to replace them with upgraded pieces, but it’s crucial to install the spark plugs with the correct gap."

I am FBO and can run Stage2+ E30 with factory Bosch plugs and coils no issues

Am I going to start getting misfires prematurely as they age?

You're quoting someones opinion.

You are fine with stock plugs. <-also someones opinion

[nissubaru]

Never seen that tool before but for $28? I'll just do it the old way

[suspenceful]

Thanks for the comments and feedback so far!

Originally Posted by type-dRew

The gains are likely even higher, because that 1-2 shift on the 'after' run was HORRENDOUS compared to the pre plug swap run.

Great write up and video, sub'd on youtube now.

Good observation - that's true! I definitely hate the stock auto trans in this, can't wait to see how much an XHP tune helps.

PS: Thanks for subscribing on YouTube!

Originally Posted by type-dRew

Also, those gap tools have existed for quite some time. BMS is just selling them with their name on it, not an original product.

I use the torque solutions unit;

https://www.maperformance.com/produc...iABEgIpvPD_BwE

While the design is similiar, I've heard the Torque Solution one is made of soft aluminum and the screw head that adjusts the electrode is flat in comparison to the cone shaped one on the BMS unit. The Torque Solution one apparently bent the electrode sideways for a member on a N5X Facebook group.

Originally Posted by TheMidnightNarwhal

"Not only is it important to replace them with upgraded pieces, but it’s crucial to install the spark plugs with the correct gap."

I am FBO and can run Stage2+ E30 with factory Bosch plugs and coils no issues

Am I going to start getting misfires prematurely as they age?

If you're not getting any misfires now, chances are that you're okay. If you continued modding and targeted ~20psi with E60, you would really want to monitor the gap with some colder plugs. But if it ain't broken, don't fix it.

[2007BMW335i]

I had the Autolite APP 5682's , about a year old. I took 2 data logs in the morning with the old plugs and 2 in the evening with the new plugs. (NGK 91784 aka LKAR8BHX) The orange and green lines are the new plugs and the blue and red lines are Autolite Double platinums. I didn't accelerate from the same rpm each time so below 4500 rpm you cannot really compare but once the boost stabilized you can see the new plugs made a huge difference. It was 3° cooler but I used SAE correction for temperature.

It was not missing or having timing corrections on the old plugs.

New Plugs: https://datazap.me/u/scottxp800/log...7-8-9-10-11-21

Approximate gap 0.021" not dragging on a 0.020" feeler gauge and a 0.022" would not fit.

This is a custom (Wedge/Ken) E50 tune 22-23 psi stock turbos. FBO except for outlets, no cats. I need to set my shift points up to see where the HP drops off and reset them to what these plugs are doing for HP and TQ at higher rpm's.

On another site (n54tech) someone said people had problems with GT-R plugs,I'm wondering what kind of problems people were having with GT-R plugs. Other than maybe fouling early due to heat range I can't imagine why there would be an issue.

Not sure anyone has tried this particular plug.(that I have seen)

PSPE® (projected square platinum electrode) provides the best ignitability and service life for high-heat engines. This NGK-patented design is recommended for turbo and supercharged engines.

https://ngksparkplugs.com/en/product...um-spark-plugs

OP should try these plugs or someone else to see if they get similar gains.

[bimmerzeit]

Here is my version (in 4K) come on Jake no more 1080p uploads! ;-p

Also, FWIW the BMW workshop manual specifies to use a flexible joint with the spark plug socket. Thought it was worth mentioning.