DIY spark plug change
- Thread starter Pondrew
- Start date
The spark plug life is driven (pun) by various factors…
General rule of thumb for stock cars is around 25k for N54s and 35k for N52s and 40-50k for N20s
Re-mapped cars divide by 2…
Of course since the DMEs try to correct faults dynamically you won’t be aware there’s an issue till they start misfiring…
General rule of thumb for stock cars is around 25k for N54s and 35k for N52s and 40-50k for N20s
Re-mapped cars divide by 2…
Of course since the DMEs try to correct faults dynamically you won’t be aware there’s an issue till they start misfiring…
B21 said:
I thought the N52 were around every 60,000 miles? Although I did mine when I got the car at around half that mileage.
Silverstar said:
Here are some other views..my primary issue or focus was re-mapped ones..
In most modern BMWs, manufactured after 2010 with the N20 or N55 engines, it is required to change spark plugs every 60,000 miles. For BMWs with V8, V10, or N54 or N63 engines, 37000 miles are the threshold before getting new spark plugs. As for BMW models between 1999 to 2009, spark plugs are replaced at 80,000 miles due to their platinum and iridium tipped plugs.
or
BMW with Platinum or Iridium spark plugs
100,000-mile interval
Example N52 motor
BMW with Two Ground Spark Plugs
60,000-mile interval
Example: N36 E37 E85 E46 M3 M Roadster
BMW M Series Spark Plug Interval
35,000-mile interval
E60 M5 E63 E64 M6 E90 E92 M3
BMW with Cooper Spark Plug Change Interval
40,000-mile interval
Example: 135i 335i 335i Engine N54, N63
Frankly I'm not sure what science BMW uses..apart from to avoid at all costs (pun) any serving expenditure in the first three years..
20k miles for a first oil change is criminal from a maintenance perspective, as is filled for life auto gearboxes etc..
What is true is that re-mapped turbos place much greater strain on plugs n coils hence why some serious tuned N54s can't get pas 15k miles without plug/coil failures..
My own 35is was OK till I remapped it then coil no 6 failed as we passed 385 bhp
On my N20 E89 Coil no 4 gave way as we went past 280bhp
20k miles for a first oil change is criminal from a maintenance perspective, as is filled for life auto gearboxes etc..
What is true is that re-mapped turbos place much greater strain on plugs n coils hence why some serious tuned N54s can't get pas 15k miles without plug/coil failures..
My own 35is was OK till I remapped it then coil no 6 failed as we passed 385 bhp
On my N20 E89 Coil no 4 gave way as we went past 280bhp
MikeyH said:
Generally no…broadly there’s a 3:1 through 2:1 range of plugs for coils..it’s an in exact science..again premium coil suppliers products tend to last longer, as do their plugs..
Eldor / NGK / Bosch tier 1 in this domain
Again on highly tuned cars 2:1 is not uncommon ratio for plugs n coils..N54s are known to get through coils in 20k when seriously tuned..
Thank you b21B21 said:MikeyH said:
Generally no…broadly there’s a 3:1 through 2:1 range of plugs for coils..it’s an in exact science..again premium coil suppliers products tend to last longer, as do their plugs..
Eldor / NGK / Bosch tier 1 in this domain
Again on highly tuned cars 2:1 is not uncommon ratio for plugs n coils..N54s are known to get through coils in 20k when seriously tuned..
Coils and plugs are not related, though, surely?B21 said:
The coil provides the electricary to facilitate the spark.
The plug give the medium to produce the spark in the correct place, no?
There is nearly as much debate around how many miles plugs 'should' be changed as there is about which tyres are best TBH.
From circa 2014 onward cars, BMW specify 'every other service' for plugs, irrespective of mileage (so I read somewhere). Absolute bollox IMHO. Plugs don't suffer from 'old age'. If they ain't being used, they ain't wearing out or getting carbon build up (the real problem with spark erosion).
If you're doing 15k miles a year, then every 4 years makes sense, but if you're doing 1.5k a year then it doesn't. Unfortunately for them manufacturers can't put a 'service indicator' on a spark plug, so came up with a generalisation IMHO.
The reason why coil / plug / state of tune are in part to design and combustion pressures..
As you say age in isolation is no predictor of the demise of plugs…duty cycle is..
Turbos have higher internal combustion pressures than NA engines..that’s why they make more power at the same displacement…
The spark has to be strong enough to ignite the mixture
Higher pressures require a stronger spark to ignite / manage the burn
The strain of trying to fire the mixture causes premature wear and stress on all the components
In the case of the N54 the engine tends to run hot and cook the coils
As the tune goes up the coils either have to have more power or the plug gap needs to be narrowed otherwise the pressure in the cylinder will be so high as to stop a spark forming correctly and then you get the misfire..
Many N54 engines have racked up big mileages and or have been tuned ..often to 600/700 BHP levels
It’s accumulated experience that shows the coil / plug / gap relationship and their associated wear / failure rates..
As you say age in isolation is no predictor of the demise of plugs…duty cycle is..
Turbos have higher internal combustion pressures than NA engines..that’s why they make more power at the same displacement…
The spark has to be strong enough to ignite the mixture
Higher pressures require a stronger spark to ignite / manage the burn
The strain of trying to fire the mixture causes premature wear and stress on all the components
In the case of the N54 the engine tends to run hot and cook the coils
As the tune goes up the coils either have to have more power or the plug gap needs to be narrowed otherwise the pressure in the cylinder will be so high as to stop a spark forming correctly and then you get the misfire..
Many N54 engines have racked up big mileages and or have been tuned ..often to 600/700 BHP levels
It’s accumulated experience that shows the coil / plug / gap relationship and their associated wear / failure rates..
B21 said:
Yeah I get that (as it makes logical sense to me). But if you increase the pressure in the combustion chamber by increasing turbo pressure and fuel volume for more power, then part of the that process of a 'remap' will surely be to re-program the electronics to give a 'bigger' spark, no?
Therefore, it makes sense to me to replace the plugs with more durable ones which are able to run hotter for the same period as OEM, whilst providing a bigger or 'fatter' spark.
I know nothing about this stuff, but I like to learn, BTW
The DME unit can’t change the magnitude of the spark…the energy available is fixed by the amount of current the DME MOSFET output stages can deliver..plus the design of the coils..it can change the duration of the spark and it’s timing..within limits
With serious re-maps colder plugs, narrower plug gaps and better quality / different coils all are solutions..
Despite all those changes plugs n coils get eaten at a faster rate..the earlier DME to the one in the Z4 N54 used to regularly fry its output stages if pushed too hard..
With serious re-maps colder plugs, narrower plug gaps and better quality / different coils all are solutions..
Despite all those changes plugs n coils get eaten at a faster rate..the earlier DME to the one in the Z4 N54 used to regularly fry its output stages if pushed too hard..