[Smooth_Operator]

I changed my spark plugs over the weekend and now my car is misfiring. There was no misfire before the change. I changed the plugs because the interval is 60k miles and I was at 64k miles, and I assume that the plugs that were in there were original to the car.

I bought Bosch ZR5TPP33 (which supersede the recommended-yet-discontinued ZR5TPP33S) plugs from FCP Euro and followed the Bentley service manual exactly. When I was done I buttoned everything up, including the four disposable stretch fasteners for the strut bars. I'm using Bimmerlink during test drives and it confirms misfiring on all 6 cylinders, though cylinder 1 was by far and away the worst. Usually cylinders would misfire once, maybe twice at a time, whereas cylinder 1 would log 15-25 within a few seconds.

When trying to troubleshoot, I focused on cylinder 1 (closest to front of car), since it was the worst, and accessible without burning through more stretch fasteners. The manual does not provide a gap spec for the plugs. Bosch says .8mm, on the box. I probably should have measured the gaps on the new plugs before putting them in the car. Nevertheless, when I took cylinder 1's new plug out and measured it, it was .63mm. All the old plugs were between .7 and .775mm, after presumably growing for some time. Maybe I'm not looking hard enough, but try as I might I cannot find the proper gap spec for this engine. The service manual doesn't list it, and whenever I search I see results for people that have tuned their engines. I'm running a car that is bone stock, save for the air intake. I gapped the new plug up to around .775mm, no improvement. I put the old plug back in cylinder 1, still misfiring, still the worst. I switch the coils between cylinders 1 and 2, assuming that all coils are bad and that cylinder 1's was the worst. No improvement, and cylinder 1 is still the worst.

It misfires when idle, and when under load. I know that is super broad but it's the best description I can give. Least likely condition to produce misfire is steady driving, around 1500 RPM. Even then it'll still miss. I am unsure how temperature affects it. At first I thought that it was worse before coming up to operating temperature, after a couple more test drives I'm not so sure.

I have disconnected and reconnected the coils many times, and pushed down on them as far as I think they can go.

I don't think I cross threaded any plugs, as I started each one by hand before finishing off with a wrench.

Throughout all of this, the car has not thrown a check engine light.

What am I missing here? Should I try with a different torque wrench? I have new coils and stretch fasteners coming tomorrow, but after swapping the coils between cylinders 1 and 2 I'm not sure the coils are the problem here.

[thejeremyman9]

Did the misfire actually produce a code or you just look at misfire counts? Does it actually affect the driveability?

You tried all the obvious stuff really. If you put the old plug back in that should confirm not plug. Swapping coils should confirm not coil. Did you use a swivel socket? A very common issue is cracking the plugs on install, which is not visible, and will cause those symptoms. Maybe you cracked the new plug then cracked the older plug reinstalling.

[Smooth_Operator]

Originally Posted by thejeremyman9

Did the misfire actually produce a code or you just look at misfire counts? Does it actually affect the driveability?

You tried all the obvious stuff really. If you put the old plug back in that should confirm not plug. Swapping coils should confirm not coil. Did you use a swivel socket? A very common issue is cracking the plugs on install, which is not visible, and will cause those symptoms. Maybe you cracked the new plug then cracked the older plug reinstalling.

The misfire did produce a few codes after my first test drive. Then I cleared the codes, and they didn't come back when I drove it again. Cylinder 1's misfire does affect drivability whenever it does 15-25 at a time, which happens seemingly at random. The car is still 100% drivable, but it's super annoying to have that big hesitation without warning.

I did not use a swivel socket, at this point thinking I might have cracked the plugs. I'm going to try cleaning out the connecters for the coils and if that doesn't work I'll buy new plugs and a swivel socket and go from there.

[Smooth_Operator]

Bought a new set of spark plugs, used a swivel socket, and experimented on cylinder 1. Cleaned out the wire connecting to the coil with compressed air. Still misfiring. I don't think it's as bad as before but it's still there. I was extra careful with the torque spec. I don't know what the problem is at this point.

[fe7565]

(Never mind, just noticed you got the spark plugs from FCP Euro, so they should be genuine. Disregard => There are reports of fake NGK spark plugs on Amazon and Ebay, etc. They look almost identical to the real ones, but have vastly varying differences in resistance.)


Still, worth a check regardless: Check the resistance range of all the spark plugs. Old ones and new ones. Same with the spark plug wires resistance.

Also, ISTA+ I believe has a spark plug check routine.

[bandook]

Just a question, have you installed spark plugs before or was this your first time? What torque wrench are you using? Click type? I can't imagine how swapping plugs can give you such an issue. I'm thinking either they are night tight enough and allowing blow by, or you didn't connect the coils correctly. I'd also double check anything on the valve cover to see if you have something disconnected. Changing plugs should not give you this issue. Install error is most likely.

[BashShah]

OK, so you installed 2 sets of plugs, but what kind of coils do you have Dephi or Bosch?
GN10571 delphi or what?

Try changing all coils? did you put a bit of silicon grease on the coils?
also, I have a 2012 F30 335i and I did not have to move any bars out of the way. I did it with a swivel and 4 inch and 6 inch extension on my socket?

yes the back 2 are slightly covered but not all the way and you should be able to slide in your extensions without moving any bar.

after how long of a drive does the mis-fires occur?
is the AC running or not?
what is your oil temp when the miss fires occur?

can you post all your codes?

[F32Fleet]

IIRC gap is .32

[weehe126]

Sounds like the coils aren't fully seated or you loosened the electrical connectors for the coils or injectors

[Smooth_Operator]

Thank you all for the replies. I was going out of town, and didn't want to spend another day doing plugs so soon, so I caved and took it to a shop. According to them, I overtorqued the spark plugs (which I was suspicious of before bringing it in, so I told them I might have overtorqued the plugs when I dropped the car off). They said that the coils (Delphi, original to the car as far as I know) were fine. They said that they ran some tests on it and determined that the problem was not electrical. I don't remember the exact wording, but the gist was that they were confident it was not wires or coils.

I pick up the car with new plugs, and it runs smoothly. I drive to AutoZone to return the second set of new plugs (first new set was Bosch ordered from FCP Euro, second was NGK from AutoZone... I only put the NGK plug in cylinder 1, and still saw misfires at idle on cylinder 1 so I put the new Bosch plug back in the car before driving to the shop). I do not notice any issues on the drive over. Out of curiosity, I plug in my scan tool and open up BimmerLink. I look at the sensor values for misfirings, and it says that misfires are still present. I drive directly back to the shop.

The next day, they get back to me and tell me this; "Codes all set at 63,990 miles. Check in mileage was 63,991. When codes are cleared in a BMW, they do not erase from memory, they set as pending or intermittent until the misfire monitor runs successfully then the DME will erase the code memory... We have since road tested 15+ miles with no misfires logged, this included time on [local interstate]. System is clear of all codes (permanent and temporary) at this time."

I need the car today, so I picked it up, expecting it to run smoothly and for misfires to show when I look at the sensor values. Sure enough, that's exactly what happened. The misfiring situation is definitely way better than before... I'm fairly sure it isn't happening on idle, under hard acceleration or at highway speeds. Since picking it up and driving for about an hour, I've only noticed the sensors detect misfires at roughly 1500-2500 RPM, around 20-45 mph. I only see one at a time on any given cylinder, whereas before taking it in I'd see 2-4 on most cylinders, and up to about 25 on cylinder 1 before resetting to 0. Throughout all of this, the air conditioning has been on. I haven't been looking at the raw sensor value for the oil temperature, but the gauge on the dashboard shows within normal expected values.

The shop I took it to said that all cars misfire, even brand new ones. Before all of this, I have peeked at the sensor values for misfires, and never seen any whatsoever. But I also wasn't paying close attention then. I'm having a hard time buying this thing about misfires being normal. At the same time, when I'm not obsessing over sensor values, the car feels like it runs smoothly, without issue. No check engine light, no codes, just sensors periodically saying that they're detecting misfires. Is there something wrong with the car at this point or am I overreacting?

[F32Fleet]

Originally Posted by Smooth_Operator

Thank you all for the replies. I was going out of town, and didn't want to spend another day doing plugs so soon, so I caved and took it to a shop. According to them, I overtorqued the spark plugs (which I was suspicious of before bringing it in, so I told them I might have overtorqued the plugs when I dropped the car off). They said that the coils (Delphi, original to the car as far as I know) were fine. They said that they ran some tests on it and determined that the problem was not electrical. I don't remember the exact wording, but the gist was that they were confident it was not wires or coils.

I pick up the car with new plugs, and it runs smoothly. I drive to AutoZone to return the second set of new plugs (first new set was Bosch ordered from FCP Euro, second was NGK from AutoZone... I only put the NGK plug in cylinder 1, and still saw misfires at idle on cylinder 1 so I put the new Bosch plug back in the car before driving to the shop). I do not notice any issues on the drive over. Out of curiosity, I plug in my scan tool and open up BimmerLink. I look at the sensor values for misfirings, and it says that misfires are still present. I drive directly back to the shop.

The next day, they get back to me and tell me this; "Codes all set at 63,990 miles. Check in mileage was 63,991. When codes are cleared in a BMW, they do not erase from memory, they set as pending or intermittent until the misfire monitor runs successfully then the DME will erase the code memory... We have since road tested 15+ miles with no misfires logged, this included time on [local [...]

Sounds normal. A long as the engine is running fine don't worry about it.

[LexsF30n55]

hi i got the same issues well when i start my car up the rpm goes up to 2k and drops down and the car stalls getting misfire codes as well
101F01 - Air mass system, plausibility: calculated air volumes in air intake system implausible.
108001 - Intake air temperature sensor, electrical: Short circuit to B+.
118002 - Mixture control: Fuel-air mixture too rich.
Knowledg 140002 - Combustion misfires, several cylinders: Damaging exhaust gas after starting up.
140010 - Combustion misfires, several cylinders: detected.
FAQ
140302 - Combustion misfire, cylinder 3: Damaging exhaust gas after starting up.
140310 - Combustion misfire, cylinder 3: detected.
140402 - Combustion misfire, cylinder 4: Damaging exhaust gas after starting up.
Connect G
140410 - Combustion misfire, cylinder 4: detected.