Do coils same time as plugs?

[jkoral]

70k on my '09 135i. No tune except for PPK v2. Was already way overdue for plugs and was planning on it next service visit.

Just started getting CEL/misfire in cylinder 6 every single time I go WOT (merging on highway, etc). Always in cylinder 6. Stopping and restarting fixes, and a couple times when I had to travel a few miles in stop and go traffic before getting off highway it's corrected itself (light goes off, misfire stops).

I was already doing plugs and I'm not doing the work myself -- should I also replace coils at the same time? Although I could DIY, I don't have the time or inclination, there are other ways I prefer to spend my free time.

Well respected indy quoted $230 plugs, $500 plugs+coils (labor + genuine bmw parts).

I know plugs+coils fix most misfire issues, worth it to just do plugs and see, or do both at the same time?

I'm also overdue for carbon cleaning, but that will have to wait.

[lowbudgethero]

Your mechanic should be able to diagnose if the coils are the cause, I wouldn't replace it unless it's the actual cause of the problem. Some people had to replace them very early, but none of the people I know personally had to replace them before 100K miles so I don't think it's that common.

230 for plugs is a lot considering it's only about 1/2-1 hour of labor for the average joe (not sure what they actually bill for), plugs are generally 80-100 bucks for OEM BMW

[PA135i]

Correct. no need to replace coils UNLESS there is one failing. And if that's the case replace only the defective coil. My mechanic told me you are not gaining anything by replacing all the coils because even a new one can fail in a year... or it can last 10 years.

[Dackelone]

You might just want to switch that #6 coil with another one and see if that code moves over to that "other" cylinder.

Is this your first plug change? The plugs should be changed every 45K miles. Really every 25 to 30K if your tuned.

I would have at least one new coil on hand... because they do break when trying to remove them. Maybe ask your mechanic how much ONE coil costs thru him... then balance that with what a set of coils costs. ?

Also make sure to use BMW dealer bought plugs(they say "BMW-Bosch" on them). The aftermarket Bosch plugs can cause misfires on the 135i. There is also a different plug for N54 vs N55... so be careful there when ordering.

Btw... I think your indi is ripping you off... they should only be charging you one to one and half hours(@labor rate) to change the plugs/coils. There is no "extra" work in replacing the coil packs - as they have to come out to change your plugs.

Also... the plastic valve cover has been known to crack. You might have your shop take a close look at yours.

135i Spark Plug replacement DIY...
http://www.1addicts.com/forums/showthread.php?t=602804

Dack

[Patriot_Pat]

I had a coil fail at 60k yesterday, not very fun.

Keep in mind all coils are subject to the same stresses, if you only change one you're gambling Delphi has somewhat poor quality control.

[6MT_Addict]

Originally Posted by lowbudgethero

Your mechanic should be able to diagnose if the coils are the cause, I wouldn't replace it unless it's the actual cause of the problem. Some people had to replace them very early, but none of the people I know personally had to replace them before 100K miles so I don't think it's that common.

230 for plugs is a lot considering it's only about 1/2-1 hour of labor for the average joe (not sure what they actually bill for), plugs are generally 80-100 bucks for OEM BMW

+1

Coils have to be pulled anyway to do plugs, so it's really no additional labour. Same procedure when re-using the old ones with the exception of new coils being removed from the packaging. Regardless, determine the cause prior to just throwing money at it

[thewubwub]

I would do the same if both haven't been changed in a while... I did for peace of mind and its really quite simple to do it yourself!

[jkoral]

Just to follow up, I ended up doing the coils and plugs. On the positive side it cured the misfire (which had been getting progressively worse and didn't even require WOT to trigger).

On the downside, I really should have done this myself (I've done plugs on other BMWs) -- 2.5 hours labor and full MSRP for parts is costly.

Worst of all my oil pan is leaking and that is definitely beyond my DIY skills (10 hours labor quoted). The comes 6K after the previous leak which was due to oil filter housing gasket and oil cooler gasket.

[bazil769]

cheapest best coils anyone and a link if possible?

[Dackelone]

Originally Posted by jkoral

Just to follow up, I ended up doing the coils and plugs. On the positive side it cured the misfire (which had been getting progressively worse and didn't even require WOT to trigger).

On the downside, I really should have done this myself (I've done plugs on other BMWs) -- 2.5 hours labor and full MSRP for parts is costly.

Worst of all my oil pan is leaking and that is definitely beyond my DIY skills (10 hours labor quoted). The comes 6K after the previous leak which was due to oil filter housing gasket and oil cooler gasket.

I think I would find a new mechanic! 2.5 hours to replace spark plugs and coils is kind of too much. Same thing with the oil pan gasket leak. I mean how much more would a dealer charge you? It can't be a 10 hour job.

Have you tried just checking the oil pan bolts for tightness ? I would also use some brake clean or simple-green and wash away the old oil. Then recheck for oil leaks. Maybe it was residue from one of your old oil leak. ?

Dack