Misfire and low battery bank 5, 7, and 8

So I changed my plugs and coils over 2 weeks ago. Tested the car everything ran great, no codes, no missfires, car felt strong. Took several trips in it and no issues.

Yesterday driving home from the office (which is only 2 miles away) I felt some shuddering, as I pulled into the garage the car lit up like a Christmas tree, check engine EML, etc. I also got a battery discharge warning.

I pulled the codes and had a misfire on 5,7,8. So now I am thinking did I not push the coils down enough, torque the plugs enough etc or is it because my battery was low.

When the car sits for a while I usually put it on a charger, which I did not have this car on because I usually drive it more in the summer, but the last few weeks I barely drove it due to travel and driving my E30.

Couple that with the fact that I am still on the original battery so we are hitting 10 years (I was going to replace but it kept working well).

So I am wondering am I getting the misfires due to the battery or do I need to go back in pull the covers off and check the coils and plugs.

I threw the car on the charger last night, when I get home today I will clear the codes, fire it up and see how she does, but was curious if the battery could cause all this, I know how sensitive the electronics on these cars are.

Alternator should charge the battery so that should not be an issue. You want to trickle charge it as it seems that your trips are fairly short and that is not enough time to charge the battery.

For plugs, I am going to assume you used the correct plugs?

Which coils did you put in? If it is any coil other than OEM, that is your issue. There are currently no 2nd hand Coils that work in this car. Period.

Ervin87 wrote

Alternator should charge the battery so that should not be an issue. You want to trickle charge it as it seems that your trips are fairly short and that is not enough time to charge the battery.

For plugs, I am going to assume you used the correct plugs?

Which coils did you put in? If it is any coil other than OEM, that is your issue. There are currently no 2nd hand Coils that work in this car. Period.

I hadn't driven the car for over 2 weeks, and the drive of 2 miles to the office would not be enough for the alternator to charge up the battery much.

Both the coils and plugs are OEM NKG with the BMW stamp.

When I changed them the car ran fine for several trips before this issue.

I had a similar issue last week. The car gave a low battery indication and the check engine light. Codes erased three times always hinting at different coils, first time 1and 4, second, 5,7,8 and third just the 8th.

The car would also go into limp mode, could not go over 3500 rpm.

Changed battery but also filled the tank with gas and added a bottle of the attached, a fuel line cleaner.

The car has been running fine since, have done 250 miles.

gnx wrote

I had a similar issue last week. The car gave a low battery indication and the check engine light. Codes erased three times always hinting to different coils, first time 1and 4, second, 5,7,8 and third just the 8th.

The car would also go into limp mode, could not go over 3500 rpm.

Changed battery but also filled the tank with gas and added a bottle of the attached, a fuel line cleaner.

The car has been running fine since, have done 250 miles.

Thanks, its sitting on the charger, which is now green, I didnt have time to drive it yesterday to see if it resolved the issue. I am going in for service on Monday to do coolant, brake, diff, and trans flush I will probably have them put in a new battery as well.

Staszek wrote

I hadn't driven the car for over 2 weeks, and the drive of 2 miles to the office would not be enough for the alternator to charge up the battery much.

Both the coils and plugs are OEM NKG with the BMW stamp.

When I changed them the car ran fine for several trips before this issue.

its been reported that some of the NGK ignition coils have gone thru a different supplier / some have ben reported to be fake.

typically the ones produced for NGK by Eldor were the good ones.

For reference

Problems With NGK 48729 Coils From Rock Auto

spammysammich wrote

For reference

Problems With NGK 48729 Coils From Rock Auto

Thanks, I bought these right before the national backorder. Mine are all stamped with the BMW logo on the top, but I do still have my originals, so if I still get the misfires I may throw them in to see.

Staszek wrote

Thanks, I bought these right before the national backorder. Mine are all stamped with the BMW logo on the top, but I do still have my originals, so if I still get the misfires I may throw them in to see.

Where did you buy them from? Easiest way to tell if it is the coils is to swap them out with a cylinder that isn’t misfiring and see if there is a change.

The only way to avoid a coil misfire is to buy OEM from BMW directly or vendors like FCP Euro who sell genuine parts.

FCP

Staszek wrote

FCP

Crazy. Well even new parts can fail. Swap them from one cylinder to another and check. Good luck.

Wanted to update this thread. I let the car sit for two days on the charger. Finally drove it today, when I first started it it was a little rough and the battery discharge light came on. Then all of the sudden it went out and the car smoothed.

I cleared the codes and went for a 15 min drive. Back roads then a stint on the highway at high speeds. Car ran fine no hicups felt really strong.

Got back to the house and read the codes again and nothing popped.

I think my battery is EOL, so I will replace it this weekend. I parked the car and threw it on the charger so I can get it in for my service appt on Monday for the other maintenance items I have to get done.

One more update, after my drive the other day I left the car on the charger. Had a chance to drive it a lot today, several trips, stop-start and highway runs. Car ran great not one light or hesitation in the engine.

Just a weird coincidence that the battery discharged a few days after I changed the plugs and coils.

New battery tomorrow and will continue to monitor it. I still have the old coils that only have 37k on them so worse thing I could just swap them back.

As an aside note I looked at all the boxes they were genuine and marked from Italy, not China.