I need help. I did a complete spark plug and coil swap on my 2016 m235. Sitting at about 103k miles. This was done in prevent and the car ran perfect prior.
Now, I am having a misfire on cylinder 2 and the idle is atrocious. I have swapped coils, the misfire doesn’t follow. I swapped the new plugs back to old, same cyl 2 code and the idle is even worse.
I truly have no clue what to do at this point and don’t really understand how the car is now running like a bag of shit after it being perfect this morning.
Edit:: I’m now getting multiple misfire codes after putting all old coils and plugs back in. I’m at a total loss.
Please help me figure this out.
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Did it happen immediately following the initial plug and coil swap, like, right from the first start post-swap, or did it run fine for a bit (even minutes) and then it started?
Not immediately after the swap, but minutes after it was first started. Initial start and idle was fine… went for a cruise down the road and maybe a 1/4 mile in it threw the drive train malfunction and flashing CEL and was misfiring pretty bad. Code never left cyl 2
When I had a similar set of symptoms (just happened randomly at idle, but nothing touched mechnically beforehand), it was a broken valve spring. $$$ fix (but I think they charged me for taking off the head but they didn’t do that or shouldn’t have needed to).
When one cylinder is lost, it can cause timing issues in other cylinders, so not surprising to see multiple cylinder misfire codes when it’s only one bad cylinder.
But could still be an injector or frayed wire.
Like another said, a compression test will tell you a lot at this point.
How much are we talking? Did you figure that out yourself or a shop? If yourself, what did you do?
I appreciate your insight.
if that is your problem. Cost me CAD$2300 from the Indy shop that did the repair (which I didn’t have any previous relationship with).
Probably more now. That was early in the pandemic when most people stopped driving.
Other costs were bmw dealership’s misdiagnosis and wrong part replacement recommendations (don’t go to a dealership, they’ll tell you to replace spark plugs and coils because they’re idiots following their flowchart).
I figured the next proper step was a compression test, which the Indy did but the dealership did not. I did the same as you: swap coils and plugs around and if the problem stays in the same place, the coils and plugs are fine.
Thanks for your input, really appreciate it
You’re not running a tune, right? Which codes are you getting exactly?
As much as I hate to even spit these words, I bought it tuned and am unable to gain control of the license or even confirm what tune it’s on.
My plan was to buy an MHD or bm3 license but haven’t gotten around to it. I’m getting p0302 which is just reading cylinder 2. P0300 has popped up too(multiple cylinder misfires)
I want to lead towards a faulty injector at this point, but I really don’t know. Here’s the biggest kicker - I’m 500 miles from my house, at my parents.
No offense but it sounds like you’re a little out of your depth with this. Especially when it was running fine and you were that far from home.
Might want to find a local Indy shop and see how soon they could take a look at it.
None taken - you would be correct at this point I’m in way over my head. My dad has been assisting the entire time and he is extremely mechanically inclined, also at a loss. I figured I’d do the sparks and coils here that way if something did go wrong I’d have someone much better suited to help. Never in a million years did I think a simple plug and coil job would turn into this.
I feel that we’ve done everything to potentially diagnose the issue aside from physically testing the cylinder 2 injector. From what I’ve read though, n55 injectors theoretically last 200k miles. I just find it extremely bizarre to all of a sudden shit out as a do the plugs, if an injector is the culprit.
That’s where we’re at with it. Going to likely load it on a trailer and take it to a shop for them to deal with it and hopefully not break my bank.
Thanks for taking the time to reply.
The injector could have been on its last leg. When was the last time coils and plugs were done? Assuming the injectors are original.
Without having access to the tune info, it becomes a lot less simple. Have you had a shop take a look at the DME? (Maybe during the PPE?)
Based on service history, plugs at 70k (just prior to me purchasing)
I don’t see coils anywhere so I guess there’s chance they were original, which is partly why I wanted to go ahead and do them with the plugs.
Bingo on the tune. I’m punching myself in the face rn over not buying my own tune the day I bought it. Boy what I would do for the info bm3 provides.
I have not had a shop look at the DME. Suppose I should ask them to do that when I drop it off, yeah?
Yeah I would definitely let them know the deal, as much as you know. Did you just not have a PPE done before you bought it?
Will do. Independent, no. (I know, my situation keeps looking worse).
The dealer I bought it from (non bmw) had it serviced and prepped for sale at a neighboring bmw dealership AND did their own inspection prior to sale, so I didn’t feel the need. Lesson learned on that accord. Not worth the risk of future uncertainty.
Check compression.
This.
Will make sure the shop it’s at does that. Thanks for your input.
I had a similar issue on my 2016 328i out of nowhere, just multiple misfires out of nowhere…got new spark plugs+coil packs…it ended up being my injectors had them replaced and coded…then I also replaced the purge canister valve but idk If that affected it… also I got new spark plugs after
I’m hoping it’s something relatively simple such as the injector. Hopefully can post an update today as it’s at a shop. Did you replace all or just one? What did that run you if you don’t mind sharing?
Well, it depends on the part cost check [FCP Euro], but I paid $150 to replace the injectors+coding, I believe I paid more for the parts than the labor… also I had put new spark plugs b4 replacing injectors they were fouled do to the faulty injectors.
So if it happens to be the injectors and you still get some misfires after replacing them, you might want to get new spark plugs.