Re: What constitutes 'severe duty' to a spark plug - re 98 Ford ClubWagon 5.4L
Severe service for a spark plug could be lots of high load
operation (hauling heavy loads, towing, etc.), or lots of
short trip driving that includes a lot of idling. The
mileage guideline are based on an assumed number of engine
hours per mile. Anything that requires more engine hours per
mile driven impacts this.
If you have a stalling problem, I'd suspect the IAC (Idle
Air Control). Depositions can build up on these and affect
there ability to stabilize the idle. They are easily removed
and replaced. Cleaning may be effective (or may not). A new
one is less than $100 at the dealer.
> The service guide for my '98 Ford Club Wagon says that my spark plugs should
> be replaced at 100,000 miles.
> With 75,000 miles on the van now, I've got mysterious stalling problems when
> approaching an intersection; i.e, when decelererating.
> I strongly suspect the engine is running lean. The leanness is not
> overwhelming, however. There is some pinging, while on the freeway,
> especially during the warmer times of the day, that was never evident
> before. The timing is OK, according to the OBDII break out.
> Nevertheless, it would probably be a good idea to change the spark plugs.
> After all, a few misfires, especially as low idle, might cause an engine to
> stall. So I looked at my service guide, and sure enough, it says I'm early
> if I only have 75K miles. But wait, there is a "severe duty schedule" that
> says the plugs should be changed at 60,000 miles.
> This van gets a great deal of work on short-haul trips. I have heard that
> this is hard on the engine lubricant. Would it wear spark plugs
> prematurely? Why? Because they're "cold" much of the time? Does "cold
> combustion" age spark plugs at an accelerated rate?
> I would especially appreciate any shared experiences on this matter.