Spark Plug Miles

[ebincia]

Hello all,

A question for those of you that run the OEM spark plugs. How many miles are you running on these spark plugs? I have 18K and they look OK, but I wonder if I'm pushing the limits.

[riceburner]

Last time I spoke to a BMW tech service guy he said they'd upped the replacement intervals to something like 24,000 miles on the plugs. (ie - every other major service interval).

I think mine were in for something like that, possibly more before I changed them recently - they were fine.

[macx]

I bought my 04 in 08 with 25k miles.

In less than 2 or 3k miles, it started to vibrate worse over a
wider rpm range and within a short time started cutting out
under hard acceleration.

I had looked at the plugs when I got the bike and they looked
fine, don't know how many miles they had on them. Wouldn't
be surprised if they were the originals.

After doing all the other service and maintenance things,
all to no avail, I broke down and changed plugs. Never ran so good.

We'll see how long these last before they start the same thing.

[Xdot]

My new-to-me '02 (21K miles, single spark motor) is a little hard starting when hot. Like if you stop to put in gas. When you go to start it, it is a little hard starting. I'm pretty sure the original plugs are still in there and in my experience with EFI cars, plugs are the first place to start. I've got a set on order and will let you know if it makes a difference.

[boxermania]

With the advent of EFI and electronic ignition the plug life has improved tremendously, even when the gap is increased beyond the service limits. A few events will diminish the plug life and they are:

1) Poor oil control
2) Extremely rich A/F mixtures and
3) Reduced or intermittent coil fire

None of the above has been much of a problem on the single plug engines; on the other hand, the stick plugs on the 4 plug engines have been rearing their ugly head of late. Stick plugs are affected by long term exposure to heat, more so on air cooled engines and begin deteriorating until they stop firing altogether, and symptoms are rough idling, hard to start and skipping during brisk acceleration.

In answer to the question, 24K to 30K miles on today's plugs with a proper running engine and electrical system is not out of the norm.

[riceburner]

Stick plugs are affected by long term exposure to heat, more so on air cooled engines and begin deteriorating until they stop firing altogether, and symptoms are rough idling, hard to start and skipping during brisk acceleration.

mainly because they're car technology that's been designed for use under a bonnet - away from huge temperature variations (air cooling as opposed to water cooling) and moisture (from the exposed positioning on the cylinder head).

[macx]

My thoughts always seem to be invaded by "what if" - usually in unexplored territory.

Having said that, if these stick coils really are that delicate and undependable (my 04
with a fresh tune and plugs has recently started to exhibit some of those symptoms
like an uneven idle, a little stumbling during hard acceleration, those typical things)
would there be any detriment to trying an external coil setup similar to that which
fires the bottom plugs?

That would get the coils away from the heat, etc etc. I haven't seen any posts
talking about the external coil for the bottom plugs failing, or for the single spark
bikes, so they must be more dependable.

I'm sure I could find a place close to the existing external coil to mount it just to
try it out. And some straight heavy silicone boots on the plug wires could probly
be coaxed onto the plugs with the help of my long needle nose and some anti sieze.
just to try it.

Only thing - ea stick coil has it's own "trigger" lead - where the external coil only
uses one. Any ideas anyone? I looked at a wiring diagram a few months ago when
I thought of this, but don't remember if there's one lead for the stick coils out of the
control and then splits - if that's the case, that would make it relatively simple.

If there's 2 separate stick coil trigger leads coming out of the control, then what?

Whaddya think? Worth a shot "just for s's & giggles"?

[BigCat]

But you have to see this in relation to cost/effort. What are we talking here, $10-$20 and 15 minutes work?
I changed mine at 9K and (think) i noticed slightly improved running (probably down to the gaps).
Would you ride another 14K to save $10?

[riceburner]

But you have to see this in relation to cost/effort. What are we talking here, $10-$20 and 15 minutes work?
I changed mine at 9K and (think) i noticed slightly improved running (probably down to the gaps).
Would you ride another 14K to save $10?

plugs aren't much - but the stick coils are something like £60 each - NOT from BMW (motorworks price last time I checked). BMW prices are a lot more!


MacX - if you do try it - let me know because I want to do it too - fed up with the poo stick coils!!

[macx]

Didn't want to openly admit it, but I've bought a used coil & wires for that reason.

Now that I know that at least somebody won't laugh me off the forum, I might do
just that - just to try it.

I just hate to throw significant money at a technical problem that can maybe be
solved for considerably less $ and, at the same time, provide a long term solution
rather than spending that $ over and over, or even to have the potential of that
happening. I'm just stubborn I guess. Plus getting laid off, so no new stick coils
in my immediate future - altho awhile ago I did score one of the new style - that
reportedly don't have at least as high a rate of failure - on ebay for about 1/2 cost
of new, supposedly low miles. Just hit the search at the right time, didn't see
many available or at reasonable cost.

Getting laid off in maybe 2 to 4 weeks, will have time to tinker, then. Going to
recheck all the tuneup items first to rule out as many other potential causes as
I can.

I even found there are long rigid "tubes" available separately for plug wires that go
down into a cavity in the head or valve cover like that - sort of like the old hemi's.
So if it works and I decide to make it permanent, I'll get those.

I do have a couple other priorities that have to come first (my 4wd trans input
seal and a couple other "minor" mechanical issues on my car plus some things on
the house - I do nearly all my own mech work, incl rebuilding auto trans & engines,
and built 99% of my house myself) so might not be until later July or even into August.

If I do it, I'll post about it, probly even a write-up with links.

[riceburner]

Didn't want to openly admit it, but I've bought a used coil & wires for that reason.

Now that I know that at least somebody won't laugh me off the forum, I might do
just that - just to try it.

I just hate to throw significant money at a technical problem that can maybe be
solved for considerably less $ and, at the same time, provide a long term solution
rather than spending that $ over and over, or even to have the potential of that
happening. I'm just stubborn I guess. Plus getting laid off, so no new stick coils
in my immediate future - altho awhile ago I did score one of the new style - that
reportedly don't have at least as high a rate of failure - on ebay for about 1/2 cost
of new, supposedly low miles. Just hit the search at the right time, didn't see
many available or at reasonable cost.

Getting laid off in maybe 2 to 4 weeks, will have time to tinker, then. Going to
recheck all the tuneup items first to rule out as many other potential causes as
I can.

I even found there are long rigid "tubes" available separately for plug wires that go
down into a cavity in the head or valve cover like that - sort of like the old hemi's.
So if it works and I decide to make it permanent, I'll get those.

I do have a couple other priorities that have to come first (my 4wd trans input
seal and a couple other "minor" mechanical issues on my car plus some things on
the house - I do nearly all my own mech work, incl rebuilding auto trans & engines,
and built 99% of my house myself) so might not be until later July or even into August.

If I do it, I'll post about it, probly even a write-up with links.

A detailed write up would be very useful!! Good luck! Sorry to hear about the redundancy though.