Thread: Spark plug Q
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      06-13-2020, 07:36 PM   #35
thejeremyman9's Avatar

Drives: 2015 BMW 335i
Join Date: May 2019
Location: Cali

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Finally Installed New Plugs

Alright folks, I just finished doing the plugs on my car. Overall not a bad procedure. I probably took twice as long because I was documenting everything and going super methodically.

First, the tools above worked great. The only thing I would add is a wire gapping tool, which is what you are supposed to use on these type of plugs rather than a fueler gauge (although that can work as well, mine wasnít the right size(s)). This is what I got:
See this post for more details on tools, plugs, etc.

The Bosch plugs I got were 0.030 out of the box, not 0.032. I was totally fine with this, since I wanted to err on the side of a slightly smaller gap since I am FBO + MHD E20 2+. If they were 0.032 I probably would not have tried to close the gap though, you really want to run them as is as long as they are within range and consistent.

The plugs I pulled out had 45k miles, were never changed, and about 5k of those miles were tuned. They didnít look bad, but did clearly show some wear on the tip as it was visibly smaller than the new ones. The gaps were 0.033 to 0.035.

The other thing I would note is that some were very hard to break loose, to the point where I was getting worried. I assume this is just because they were the original ones. Also, the threads were pretty rusty, even though my car is a CA car, has never seen snow, and is overall extremely clean. Because of the rust, the plugs were hard to spin out by hand, and the threads were squeaking as I was spinning them. Also, if you scroll through the picture below, you will see that they left quite a bit of debris down in the plug hole after pulling them out (I cleaned with compress air etc before pulling them, so this was from pulling the plugs out). I used a vacuum with a stray and it worked very well to vacuum that debris out before putting the new plugs in. I also ran the new plugs up and down through the threads a few times to clean the threads since the definitely had some buildup on them (I was actually worried it might mess with torque spec, so I went closer to 20 ft lbs).

Also, you definitely need a locking extension or need to tape your extension to your ujoint and socket if you get the one with the rubber insert, it grips the plugs extremely tight. Overall a good thing but it will get stuck on the plug if you donít secure it to the extension. The Ujoint worked fine, but I would probably just go for the swivel socket from ECS if you havenít ordered the socket yet.

Here are the logs taken 2 days ago, same tank of gas, etc:




You can see that timing isnít too bad, but its pretty inconsistent and in most logs I get a few degrees pulled randomly from different cylinders. Was the same when I was on stage 1 and on stage 2+ 91 octane maps.

Now, here are the new logs taken today, again same tank of gas etc. No changes except the plugs. Bosch plugs from FCP euro at 0.030. I only drove about 5 miles before logging; not sure if there is any adaptation period, but ill log again in the near future and check.

Two 1-4 (both at the link, use the change log dropdown):

Three 4 (again use the dropdown to change):

In the 4th gear logs, Timing still isnít perfect, which is a little disappointing. Its similar behavior as with the old plugs, with 1-2 random cylinders getting timing pulled. Maybe a slight improvement, hard to say. The timing does feed back in, so its possible there is just a misfire early on as it generally seems to pull timing on one cylinder right when peak boost hits. I put the 2 before and the 3 after logs in VD and they are basically the same, although one of the new ones (orange line) does show the smoothest curve.

My 1-4 logs actually look worse, which is confusing and annoying. Thereís a ton of timing being pulled and Iím not sure why. At this point I am just hoping that I need to put some miles on them. I might also reset adaptations and just drive like 50 miles and log again to see what happensÖ. Wont happen today though. The weather was warmer but IATs were not considerably higher so I am not sure I would attribute it to that. These 1-4 logs were the last ones I did, after doing probably 6 pulls and driving aggressively in a 5-10 minute window. Could be a factor. I did overboost a bit in the first 1-4 log and I can see MHD start to close the throttle so maybe the timing was a result of that as well.

I would note all of this is imperceptible in the car; the car pulls strong and runs fine. No codes or anything. Hard not to be a little disappointed with the logs, but Iíll give it a little time and maybe another tank of gas and log again. Just strange because ozymandias435 installed the exact same plugs and had perfect timing, although he was running 93 tune (and BM3), not an ethanol map with crappy CA 91 octane gas.

Hereís the album. Photos got a little out of order for some reason, but all the plugs and coils, etc, are shown in here. Also found a bunch of leaves in the passenger side area and tried to get those out, and pulled my filter to take a look.

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