Mild misfires - Which plugs & coils to use on a tuned car?

[asbrr]

Hi Guys,

Lots of discussion on this, lots of different contexts. I have not been able to find a good consensus on what plugs and coils are recommended for an N52 w/ tune.

Context: I have a 128i w/ BPC Stage 1 tune, car now has 120K kms on it (75K miles). Tune was put in around 4 months ago, car ran great and felt a lot more muscular than before. Started to notice a mild hiccup about 2 months ago, if I apply part throttle below 2krpm in a higher gear. I don't typically lug the engine, but will use the low end torque to accelerate gently even if in a high gear. Car before did not complain about this, but started stuttering a little while ago and it has progressively gotten worse.

My theory is the tune is asking more of the engine, and the original plugs & coils can't supply the requested spark/strength that the tune requires. Likely accelerated the wear and now things are starting to go.

So - my question is what plugs/coils do people have good experiences with? There is a huge price difference between BMW parts and alternatives. This Bosch set at ECS is on sale right now:

https://www.ecstuning.com/b-assemble...2137594937kt2/

I've heard of people liking NGK with Delphi coils....but there are so many part numbers, even between sites, so hard to figure out what is good

Any help appreciated thanks.

[desertman123]

This isn't an N54 so don't worry too much about plugs and coils. Replace with non-BMW to save some cash and you'll be fine.

I put NGKs in my car when I took Boschs out and never have any issues. (As far as I know) stock coils at 107k mi, although not tuned.

While you're at it, just do a whole tuneup. Clean VANOS solenoids and filters, clean MAF, make sure you got clean good quality 91+ octane.

[chris_flies]

Originally Posted by desertman123

This isn't an N54 so don't worry too much about plugs and coils. Replace with non-BMW to save some cash and you'll be fine.

I put NGKs in my car when I took Boschs out and never have any issues. (As far as I know) stock coils at 107k mi, although not tuned.

While you're at it, just do a whole tuneup. Clean VANOS solenoids and filters, clean MAF, make sure you got clean good quality 91+ octane.

Pfft, 91 octane...
87 works just fine! My car does not like 93 Sunoco stuff from the track, it developed a lumpy high idle after start-up, but would settle down.

Since you'll have the engine cover off, you might as well do some of this, though, if you don't have any real problems, it probably isn't worth your while to dig into all of that.

[asbrr]

Ended up going with NGK Iridium plugs, and Delphi coils from RockAuto. Car runs butter smooth again!

[gjm120]

Curious what NGK plug you used? I bought NGK plugs based on the one shown in RealOEM: LZFR6AP11GS NGK stock #95712.

[asbrr]

Originally Posted by gjm120

Curious what NGK plug you used? I bought NGK plugs based on the one shown in RealOEM: LZFR6AP11GS NGK stock #95712.

Yes good point, there are 2 types of plugs from NGK. I went with the 95712 like you did, that's the only ones RockAuto had.

ECS lists 2 types:

Laser Iridium Spark Plugs (ILZFR6D11)
Spark Plug - (LZFR6AP11GS)

NGK's site lists the 95712, so that's what I went with.
https://www.ngk.com/Automotive-NGK-c1411.aspx

[gjm120]

Originally Posted by asbrr

Yes good point, there are 2 types of plugs from NGK. I went with the 95712 like you did, that's the only ones RockAuto had.

ECS lists 2 types:

Laser Iridium Spark Plugs (ILZFR6D11)
Spark Plug - (LZFR6AP11GS)

NGK's site lists the 95712, so that's what I went with.
https://www.ngk.com/Automotive-NGK-c1411.aspx

It seemed the safe bet since it's listed on RealOEM and NGK. I got them at an real bargain from Sixity Auto awhile back. Didn't need them yet so in my inventory.

A thought about your tune and plugs - maybe the tune places more demand on the plugs and they die or foul quicker?

[asbrr]

Originally Posted by gjm120

It seemed the safe bet since it's listed on RealOEM and NGK. I got them at an real bargain from Sixity Auto awhile back. Didn't need them yet so in my inventory.

A thought about your tune and plugs - maybe the tune places more demand on the plugs and they die or foul quicker?

Yes I think that was the case....with the OEM tune I'm pretty certain things would have been fine. If you look at how much extra torque the BPC tune generates over stock in some areas of the RPM curve, I have no doubt it is pushing the envelope as far as timing and spark are concerned....so with the mileage on the plugs along with age, not surprised they started to go.

Based on what I felt and in speaking with my mechanic, it was classic plug failure most likely and not a coil - car would stumble under "heavy load" conditions, but no check engine lights (mechanic confirmed he has seen this often when a plug is about to go, vs a coil going).

Butter smooth and muscular once again...too bad the winter tires are now on