[tcphoto]

I only replace parts that need replacing, I had one coil go bad shortly after buying my car only replaced one. Why replace what is good?

[crashoverride]

Originally Posted by Taylored

Any recommendation on a brand for the coils? I ordered NGK plugs.

Not sure what engine month or year you have. As that can make a huge difference. But overall I don't think there is much of a difference between the brands for the coils

[crashoverride]

Originally Posted by tcphoto

I only replace parts that need replacing, I had one coil go bad shortly after buying my car only replaced one. Why replace what is good?

Waiting till failure doesn't mean they are still good. Just means they haven't failed

Coils and spark plugs have about the same lifespan. When someone says they are replacing spark plugs it's best to replace the coils as well.

The coils wear out and get weaker causing performance and other issues. If one has failed then the rest are not far behind. Having one strong amongst many weak can make managing the engine a challenge. Common best practice as stated by BMW and the parts manufacturers says it's not good to mix and match new and used.

[StradaRedlands]

I replace all the coils at the same time... they're the same age, so while one may be an outlier, the rest probably aren't too far behind. I have to do it now, just waiting to get the motivation to pull the cowl. I have new plugs as well, as they have 75k on them. Coils are at 125k, so have served well.

FWIW, I've always used Delphi coils and never a problem.

[Mike K]

Originally Posted by Taylored

Any recommendation on a brand for the coils? I ordered NGK plugs.

I went with the Bosch coils from FCP for best reliability.

[lordnikon]

Delphi is the updated coils for E90. If I would need to replace them again I'll go for Eldor

[StradaRedlands]

Also Dinan is an option... almost able to qualify for a badge!

[Suvorovo]

Originally Posted by Mike K

I went with the Bosch coils from FCP for best reliability.

Don't get bosch man. I bought a set of 6 since I didn't have the time to replace the connectors on my pre 4/06 car. One was broken right out of the box.

[Efthreeoh]

Originally Posted by StradaRedlands

I replace all the coils at the same time... they're the same age, so while one may be an outlier, the rest probably aren't too far behind. I have to do it now, just waiting to get the motivation to pull the cowl. I have new plugs as well, as they have 75k on them. Coils are at 125k, so have served well.

FWIW, I've always used Delphi coils and never a problem.

I'm at 136,500 miles on a set of Delphi coils that I replaced at 287,500 (the orginial factory coils). IIRC I bought them from BMW of Sterling.

[Efthreeoh]

Originally Posted by crashoverride

Waiting till failure doesn't mean they are still good. Just means they haven't failed

Coils and spark plugs have about the same lifespan. When someone says they are replacing spark plugs it's best to replace the coils as well.

The coils wear out and get weaker causing performance and other issues. If one has failed then the rest are not far behind. Having one strong amongst many weak can make managing the engine a challenge. Common best practice as stated by BMW and the parts manufacturers says it's not good to mix and match new and used.

I have to disagree with coils and plugs have the same life span.

Having two N52's, one in my E90 '06 325i and one in my Z4 '08 3.0si Coupe my experience has not been plugs and coils have the same mean time between failures. On average, the E90 ran for 7 years at 35,000 miles annually until 2015 when I acquired the Z4 the E90 dropped to 22,000 annually and the Z4 17,300 annually. In late 2019 I picked up a '05 E46 that went into the daily mix and the E90 dropped to 14,700 annually and the Z4 6,800 annually (with the E46 at 14,800 annually for just two years). So, the two N52's saw similar use cases, but with the E90 271,000 miles when the Z4 went into the mix starting at 23,000 miles on the clock. Both engines require plug changes at 100,000-mile intervals. The E90 lost a coil on cylinder No. 5 in August 2015 at 287,500 miles. Because the E90 was nearing 100,000 miles on its 2nd set of plugs, I replaced the brace of coils and plugs (early by 13,000 miles) at 287,500 miles.

As of March 2024, the E90 got new plugs 96,000 miles later at 383,400 miles, the engine picked up a low RPM-high load misfire. The E90 now at 424,000 miles is on its replacement (Delphi) coils from the replacement event at 287,500 miles. The Z4 got its first set of replacement plugs at 100,356 miles and now at 120,000 miles is still on its factory coils. Since 2022, my commute to my office is now just 27 miles round trip and the E90 now sees just 4,000 miles a year and the Z4 2,000 miles per year. I have three other cars that I daily in addition to the E90 and Z4, which explains the lower annual miles on each car. It will be interesting if the short trips have any effect on coil life. I will, of course, keep track of it.

MY 2010 N52's changed plug types and dropped to 60,000-mile plug replacement. Following your suggestion, owners would be replacing coils on 2010 thru 2013 model year N52's at 60,000-mile intervals, which IMO based on my experience, is unnecessary and a serious waste of money considering the price of N52 coils.

Just my 2-cents. Not flaming.

[gbalthrop]

Originally Posted by Efthreeoh

... The E90 lost a coil on cylinder No. 5 in August 2015 at 287,500 miles... The E90 now at 424,000 miles is on its replacement (Delphi) coils from the replacement event at 287,500 miles. The Z4 got its first set of replacement plugs at 100,356 miles and now at 120,000 miles is still on its factory coils...
MY 2010 N52's changed plug types and dropped to 60,000-mile plug replacement. Following your suggestion, owners would be replacing coils on 2010 thru 2013 model year N52's at 60,000-mile intervals, which IMO based on my experience, is unnecessary and a serious waste of money considering the price of N52 coils. Just my 2-cents.

ANYONE have RELIABLE FACTS related to CHANGE of Mfr of coils/ plugs by BMW at factory during N52/E9x Model Run? Forum posts have stated that at SOME point, BMW changed recommendation of Plugs from Bosch to NGK, and coils from Bosch to Delphi. Inquiring minds want to know WHY (as to EACH such change)?
1) Quality/ price of components as supplied to FACTORY change?
2) Other financial benefit to BMW to "change"? Other "supply issues"?
3) Quality/Price of replacement parts supplied to dealers change?

Anecdotal: My Experience:
My SINGLE N52/E90 Experience is similar to that of "F30" (although I drive a LOT less miles ;-). When I got my 328xi in 2017, it had 130,000 miles on it. In first two weeks after purchase, it TWICE had "Misfire" at ~ 6K RPM, WOT acceleration in 1st/2nd, with Injector Shutdown on that cylinder. Rough running occurred for ~ 1 minute driving "Sanely", until Injector function was restored by DME, at which time "all was well", & LOUD Pedal function was normal.

Ordered New Bosch Platinum plugs ($50) and ONE Bosch coil, just in case. Upon removing coils & plugs, plug gap was 0.055" to 0.060" on the plugs that appeared to be FACTORY. Probably could have "Re-Gapped" original plugs. I'm CHEAP, but for $50? Anyone remember the days: Leaded gas & before Electronic Ignition, when gas stations had plug-cleaning machines (sand-blast)?

ONE of the coils (NOT on the cylinder that had misfired) had a cut in the plug boot, so I replaced that coil with NEW Bosch, which had SAME part# as original 6. I retained the coil I replaced (see below ;-)

No DME fault codes or issues for 5 years. I then got intermittent Low RPM "Misfire" on cylinder #4, where NEW coil was installed. Swapped #4 & #1 coils & Misfire followed coil. Replaced 2017 Bosch Coil with 2007 FACTORY Bosch Coil (after wrapping plug boot w/electrical tape. NO issues/faults since. 2017 Bosch Coil: "Made in Slovenia". Original/Factory Coils still going strong at 141,000+ Miles & 17 years. I'm retired & don't put many miles on car, but do WOT acceleration in 1st/2nd at least ONCE every time out (Systems-Check & De-Carbonization ;-)

I'm NOT an automotive engineer, & have never "Dissected" a coil. My understanding: it is basically a "Transformer" with Primary & Secondary "Windings"/ NO Moving Parts (other than the connector clamp ;-). I am NOT aware of any "Test Method" for a COP coil, but can't see how it can "get weak with age". I have "done that" (currently Rotator Cuff issues), but NOT my Factory Coils.

So for anyone STILL reading:
My experience/ Anecdotal Evidence suggests: OLD Parts are still GOOD Parts (until they FAIL); I am NOT aware of any reliable method of predicting Coil failure; Parts made BEFORE the "Great Recession" MAY be better than those made SINCE; Bosch coils made in Slovenia (at least the ONE I bought ;-) MAY be inferior to Bosch coil of SAME BMW part# made in Deutschland; Replacing ONE coil with SAME Brand/ Part# as other 5 does NOT adversely affect performance; Bean-counters MAY currently control BMW, rather than Engineers.

Your (conspiracy) theories MAY DIFFER.
George

[StradaRedlands]

I 100% agree that the coils don't need to be replaced with spark plugs, or even when one of them goes bad. That said, I go ahead and change all coils out when the first one goes. I assume the others are of the same vintage/mileage and are bound to go sooner rather than later. But I guess I kind of wait till that tell-tale before doing them.

FWIW I do plugs @ 100k intervals (NGK Iridium). It happens to coincidentally be right now @ 125k and I'm doing both on the 328i as the car is new to me and I don't have a solid maintenance history (hand-written note says both were done in 2017, but???). My 330i needed a single coil @ 215k and I went ahead and replaced all of the original ones at that time (plugs were done @ 100k & 200k). The 528i is still on all original coils at 130k, with new plugs @ 110k.

[krhodes1]

Originally Posted by tcphoto

I only replace parts that need replacing, I had one coil go bad shortly after buying my car only replaced one. Why replace what is good?

Because when they get old enough to fail, when one fails, the rest are likely to be close behind. I am not into playing whack-a-mole.

If one fails obviously prematurely, then slightly different story. Could be a one off, but also could be a bad batch. For something as relatively cheap as coils, I would still probably replace them all and not worry about it for a long time.

[krhodes1]

To add a datapoint FWIW - my N52 '11 328! is on it's original coils and plugs at 54K. My '11 128i had recently had the coils and plugs replaced when I bought it at 46K four years ago.

The 328! also has ALL it's original trifecta of gaskets in place, while the 128i has had all three replaced - valve cover and oil pan before I bought it, OFHG when I did a big service after buying it - it was JUST starting to leak.

The big difference between the cars? The 328! has lived it's whole life in cold Maine and has no idea what stop-and-go traffic is. The 128i spent it's whole life prior to my purchase in hot as the surface of the sun and traffic infested Austin, TX. Heat is very much the enemy of both coils and gaskets in these cars.

[gbalthrop]

Originally Posted by krhodes1

... The big difference between the cars? The 328! has lived it's whole life in cold Maine and has no idea what stop-and-go traffic is. The 128i spent it's whole life prior to my purchase in hot as the surface of the sun and traffic infested Austin, TX. Heat is very much the enemy of both coils and gaskets in these cars.

You SURE it's NOT the "factory upside-down "i" option" on the 328i? "Everybody's saying".
George

[Efthreeoh]

Originally Posted by gbalthrop

ANYONE have RELIABLE FACTS related to CHANGE of Mfr of coils/ plugs by BMW at factory during N52/E9x Model Run? Forum posts have stated that at SOME point, BMW changed recommendation of Plugs from Bosch to NGK, and coils from Bosch to Delphi. Inquiring minds want to know WHY (as to EACH such change)?
1) Quality/ price of components as supplied to FACTORY change?
2) Other financial benefit to BMW to "change"? Other "supply issues"?
3) Quality/Price of replacement parts supplied to dealers change?

Anecdotal: My Experience:
My SINGLE N52/E90 Experience is similar to that of "F30" (although I drive a LOT less miles ;-). When I got my 328xi in 2017, it had 130,000 miles on it. In first two weeks after purchase, it TWICE had "Misfire" at ~ 6K RPM, WOT acceleration in 1st/2nd, with Injector Shutdown on that cylinder. Rough running occurred for ~ 1 minute driving "Sanely", until Injector function was restored by DME, at which time "all was well", & LOUD Pedal function was normal.

Ordered New Bosch Platinum plugs ($50) and ONE Bosch coil, just in case. Upon removing coils & plugs, plug gap was 0.055" to 0.060" on the plugs that appeared to be FACTORY. Probably could have "Re-Gapped" original plugs. I'm CHEAP, but for $50? Anyone remember the days: Leaded gas & before Electronic Ignition, when gas stations had plug-cleaning machines (sand-blast)?

ONE of the coils (NOT on the cylinder that had misfired) had a cut in the plug boot, so I replaced that coil with NEW Bosch, which had SAME part# as original 6. I retained the coil I replaced (see below ;-)

No DME fault codes or issues for 5 years. I then got intermittent Low RPM "Misfire" on cylinder #4, where NEW coil was installed. Swapped #4 & #1 coils & Misfire followed coil. Replaced 2017 Bosch Coil with 2007 FACTORY Bosch Coil (after wrapping plug boot w/electrical tape. NO issues/faults since. 2017 Bosch Coil: "Made in Slovenia". Original/Factory Coils still going strong at 141,000+ Miles & 17 years. I'm retired & don't put many miles on car, but do WOT acceleration in 1st/2nd at least ONCE every time out (Systems-Check & De-Carbonization ;-)

I'm NOT an automotive engineer, & have never "Dissected" a coil. My understanding: it is basically a "Transformer" with Primary & Secondary "Windings"/ NO Moving Parts (other than the connector clamp ;-). I am NOT aware of any "Test Method" for a COP coil, but can't see how it can "get weak with age". I have "done that" (currently Rotator Cuff issues), but NOT my Factory Coils.

So for anyone STILL reading:
My experience/ Anecdotal Evidence suggests: OLD Parts are still GOOD Parts (until they FAIL); I am NOT aware of any reliable method of predicting Coil failure; Parts made BEFORE the "Great Recession" MAY be better than those made SINCE; Bosch coils made in Slovenia (at least the ONE I bought ;-) MAY be inferior to Bosch coil of SAME BMW part# made in Deutschland; Replacing ONE coil with SAME Brand/ Part# as other 5 does NOT adversely affect performance; Bean-counters MAY currently control BMW, rather than Engineers.

Your (conspiracy) theories MAY DIFFER.
George

Yes, coils are just small electrical transformers. They can wear out because they constantly energize and de-energize based on RMP, which causes heat and micro-expansion/contraction of the wires. They wear out when the windings lose the protective insulating covering on the individual wires and then the wire coil (winding) shorts and does not pass electrical current. Once the current no longer flows it can't induce voltage in the secondary winding.

[gbalthrop]

Originally Posted by Efthreeoh

Yes, coils are just small electrical transformers. They can wear out because they constantly energize and de-energize based on RMP, [?] which causes heat and micro-expansion/contraction of the wires. They wear out when the windings lose the protective insulating covering on the individual wires and then the wire coil (winding) shorts and does not pass electrical current. Once the current no longer flows it can't induce voltage in the secondary winding.

So if YOUR E90 coils have averaged > 200,000 miles, my Factory Bosch Coils are still going strong at > 140,000 miles, and a "made in Slovenia" Bosch coil of same part#, bought in 2017 failed in 5,000 miles, that seems to suggest failure (at least in my case) is due to some issue in manufacturing or quality control, and NOT design.

As you suggest, Heat in the coil windings (or perhaps heat cycles), will eventually cause failure of the windings. At 3,000 RPM each coil is firing 25 times per second, or > 1200 times per mile. So your E90 coils have fired > 240,000,000 times (in 200,000 miles) without regard to Idling or "Non-cruising" use. BTW, What Brand were your original/ Factory E90 Coils, replaced in 2015? What about Z4 Factory Coils?

With the BILLIONS of COP (Coil On Plug) coils that have been produced world-wide in last 30 years, SOMEONE must have done some testing/ research on failure modes, causes, and/or cycles to failure. Is concern for corporate "Security" or "Proprietary Information" so great that we can't get information from 20 years ago when these cars were designed? NObody Cares?
One more "Win" for the "Bean-Counters".
Next Up, in this Thread titled "N52 Serpentine Belt": Aluminum Bolts.
George

[Efthreeoh]

Originally Posted by gbalthrop

So if YOUR E90 coils have averaged > 200,000 miles, my Factory Bosch Coils are still going strong at > 140,000 miles, and a "made in Slovenia" Bosch coil of same part#, bought in 2017 failed in 5,000 miles, that seems to suggest failure (at least in my case) is due to some issue in manufacturing or quality control, and NOT design.

As you suggest, Heat in the coil windings (or perhaps heat cycles), will eventually cause failure of the windings. At 3,000 RPM each coil is firing 25 times per second, or > 1200 times per mile. So your E90 coils have fired > 240,000,000 times (in 200,000 miles) without regard to Idling or "Non-cruising" use. BTW, What Brand were your original/ Factory E90 Coils, replaced in 2015? What about Z4 Factory Coils?

With the BILLIONS of COP (Coil On Plug) coils that have been produced world-wide in last 30 years, SOMEONE must have done some testing/ research on failure modes, causes, and/or cycles to failure. Is concern for corporate "Security" or "Proprietary Information" so great that we can't get information from 20 years ago when these cars were designed? NObody Cares?
One more "Win" for the "Bean-Counters".
Next Up, in this Thread titled "N52 Serpentine Belt": Aluminum Bolts.
George

Well, I've actually spent time looking for a titanium bolt to replace the aluminum tensioner bolt. Not sure why that would not be a reasonable solution.

[Taylored]

Small update for the ones that are interested. Coolant leak was the mickey mouse flange thing. OFHG replaced as well now. Also did an oil change while I was at it.

Currently waiting for new laptop so i can get inpa/ista working. And check for the hidden codes on the waterpump.

Spark Plugs and valve cover gasket are first on the list now. After that rear schocks and then front. When thats done some new rims.