Why you NEED New Plugs & Coils prior to a JB4 Install

If you have been around our site and read a few of our other posts, you know we preach one thing: changing your spark plugs and ignition coils BEFORE you install a JB4. Well I didn’t follow my own rule…

I was sitting at work and got a notification that a new item had been posted for sale on the Facebook marketplace in one of the BMW Parts groups I am in. It was a used N54 JB4 for $320…and it was 10-minutes away from my house. I couldn’t resist the temptation, as I have been itching for more power for the past few months, but had been traveling too much to really work on my car. Needless to say, I went to pick it up right after work.

The JB4 was just too tempting…

My car is an ’08 135i and I just bought it a few months back with only 32.5k miles on it. Being so low mileage, I figured there were probably plenty of parts on the car that had never been changed since leaving the factory. It’s safe to say that my spark plugs and ignition coils had never been changed. I figured this was the case, and it was next on my list of to-do’s for the car. But, after seeing the JB4 right in my area, I couldn’t say no and had to get it.

To get to the point, I ignored everything we preach about here on BMW N54 Tuners, and installed the JB4 without changing my ignition coils or spark plugs. And well, you can probably guess what happened. If you can’t, I suggest you keep reading.

Misfire after Misfire

I started driving down my street towards the entrance ramp to the highway so that I could really test out the JB4. The speed limit in the neighborhood is 30mph, so I couldn’t really get on it, but even at such slow speeds, the power of the JB4 was noticeable. The throttle response was so much quicker and the acceleration off the line was invigorating. My tires are getting towards the end of their life, and even under modest acceleration, the tires wouldn’t hook-up.

I got to the entrance ramp of the highway, and put my foot to the floor. Right at about 4k rpms, before the full fun kicked it, the engine started misfiring like crazy. It felt as if you were in first gear and floored it, took your foot all the way off the gas, then floored it again constantly (obviously without the acceleration part happening). The misfires went on for about 20 seconds, and I cringed the whole time.

The ECU usually takes awhile to adjust to the tune, so I drove around easy for 15 minutes and tried again. Right as I hit 4k, the sputtering started again, nonstop. This time I just put my head down and drove the car back to the garage. I turned off the JB4 and called it a night.

Now I have to play the waiting game…

I was so excited to pack the extra 80hp on the car, and now I am stuck waiting for new ignition coils and spark plugs to arrive in the mail, and then for me to have time to install them. Every time I get in my car, I so badly want to turn the tune on, but I can’t.

There was an SRT-8 right next to me on the highway the other day, and his license plate was “UREADY”, so I knew this guy was into his car and probably up for a challenge. As badly as I wanted to show him and his V8 up, I couldn’t because without the JB4, I didn’t have chance.

Plugs and Coils BEFORE a JB4

I am going to reiterate this again: put new spark plugs and ignition coils on your car before you install a JB4, rather than after. Even one bad plug or coil will set you off misfiring, and you will be stuck playing the waiting game just as I am.

Buy the spark plugs and ignition coils before you buy the JB4, just in case. I recommend installing them prior to the JB4, but you don’t even have to do that. If you are like me, and like to get every last bit of life out of your car parts before replacing them, buy the parts but don’t install them until you start misfiring and realize they need to be changed. If you wait until you experience this problem though, you will be stuck waiting a week or longer for them to arrive in the mail.

We Now Offer Store-wide Free Shipping

As a little plug, we now offer store-wide free shipping on all of our parts, including spark plugs and ignition coils. And we didn’t increase any of our prices for this! We used to charge $9.95 and realized that was just highway robbery. When we buy things online, we hate paying for shipping, and know you do too. Most stores that give you free shipping mark their parts up to compensate for the additional costs…we didn’t do that either. Same prices, just free shipping.

Buy N54 Spark Plugs Here: https://bmwsparkplugs.com/product/bmw-n54-oem-spark-plugs/

Buy N54 Ignition Coils Here: https://bmwsparkplugs.com/product/bmw-n54-ignition-coils/