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Fuel Mileage, Spark Plugs

3K views 19 replies 12 participants last post by  fonque 
#1 ·
so i went from a consistant 36 mpg to 29 mpg with no changes in driving style. i later found out that the gas station i was using switched (ALL) grades of fuel to the ethanol blend. i was using the 89 octane to get the real gas. 2 months of 29mpg and i went into the Shell station and asked them if they quit having "real" gas. Yes she replied about 2 months ago: Problem Solved. so i searched around and found other places to fuel up and it stayed 29mpg. i was puzzled and quite disappointed. Love the car, but at 29 mpg i was not happy (there is no reason this vehicle should not get an easy 35-40 with somewhat easy driving style.

So i get out the manual after an oil change and notice *change spark plugs at 15K. i thought this was a misprint at first (all the cars i've had in the past who knows how long have been 60K-100K plug changes) i was at 19,xxx miles, and it started getting the 29mpg right about the 15K mark. so i changed the plugs (about $12 for autolite platinum) and what do you know i got 35 mpg the first time out. Problem Solved, i hope. (now the only places i can find the real gas are to much of an inconvienence, so i get the 87 oct ethanol blend)

next up, air filter change :)
 
#3 ·
60-100k MILE plug changes? Man, what cars were YOU driving? I've always ever seen 15-20k KILOMETER plug changes and 12k KILOMETER air filter changes on every car I've ever driven. I'm honestly surprised here, heh.
 
#4 ·
Ford and GM boost the 100.000 mile tune up. (On certain vehicles) Which I think involves changing the spark plugs pcv and a few other items they charge big bucks for. I noticed too (in the owner’s manual) the 30.000 and 60.000 mile service involves changing the spark plugs. As well as the timing belt. I think with a good quality spark plug, the 30 thousand miles change is over kill. A belt should last at least 90 thousand,,,yes? I guess to say with in the warranty requirements we must do these things.

But I’m no auto mechanic or automotive engineer.
 
#5 ·
I've only owned small import (two Mazdas and a Hyundai) cars so maybe it's a small car thing. 30/60k miles is like 60/120k km though, and that seems like an insanely high number to go up to before changing the plugs. Ah well, different cars, different engines. Whatever keeps them going I guess.
 
#7 ·
#8 ·
its based on the plug type copper plugs are 15 - 30K and platinum plugs are 60K - 100K. It all depends on driving style and engine condition.
Any engine troubles that cause changes in your air/fuel ratio will foul them out faster, i.e. air leaks, leaky injectors, leaky piston seals, leaky valves, etc. I would hope that no one on this board is running into any of these problems yet.
 
#9 ·
QUOTE (fonque @ May 24 2009, 04:11 PM) index.php?act=findpost&pid=238018
its based on the plug type copper plugs are 15 - 30K and platinum plugs are 60K - 100K. It all depends on driving style and engine condition.
Any engine troubles that cause changes in your air/fuel ratio will foul them out faster, i.e. air leaks, leaky injectors, leaky piston seals, leaky valves, etc. I would hope that no one on this board is running into any of these problems yet.

our oem plugs...im assuming they're copper plugs??
 
#12 ·
interesting.

i'm at 45,000kms.

i need to do an oil change soon - but i get that done at a shop to avoid the mess. (w/ amsoil i order online via komptek.)

maybe i should replace my spark plugs?

i've only ever replaced plugs on a 1985 vw golf. is it just as easy to access the plugs, remove and replace them, on my accent? any special tools required?
 
#13 ·
there's something covering 2 of the plugs. takes a small socket (can't remember size) to remove 3 bolts and then take out plugs. need sparkplug socket, extension, ratchet. i put on some (name escapes me, but it's for the threads so they don't freeze on, and some dylectic grease (electrical) (also don't know how to spell it, auto shop will tell ya what you need) only problem i had was dropping a socket behind the engine (i'm husky so squeezing the hand and arm was nearly impossible, lots of cursing, but i finally got it) 10 minute job, took nearly an hour.

read the manual for my 07 ford EDGE today, and plugs get changed at 90,000 miles. :)
 
#14 ·
so i just checked my manual and it says to change the spark plugs at 48k kms, so i'm not overdue yet.

but what IS going to be an expensive pain in the **** is the timing belt... has to be done at 60k kms, so in a few months or so. that's going to suck the big one.
 
#16 ·
QUOTE (ewing @ May 26 2009, 04:56 AM) index.php?act=findpost&pid=238260
interesting.

i'm at 45,000kms.

i need to do an oil change soon - but i get that done at a shop to avoid the mess. (w/ amsoil i order online via komptek.)

maybe i should replace my spark plugs?

i've only ever replaced plugs on a 1985 vw golf. is it just as easy to access the plugs, remove and replace them, on my accent? any special tools required?
Not hard at all I just hit 40,000 so I changed the Champions out for NGK's and switched to 0-20 Amsoil from Komptek.Plugs took about 20 minutes,no problems removing the boots at all.You will need metric sockets for the retaining bolts though.I think they were 7mm.
 
#17 ·
QUOTE (Tango2Go @ May 27 2009, 11:37 PM) index.php?act=findpost&pid=238816
Not hard at all I just hit 40,000 so I changed the Champions out for NGK's and switched to 0-20 Amsoil from Komptek.Plugs took about 20 minutes,no problems removing the boots at all.You will need metric sockets for the retaining bolts though.I think they were 7mm.
let us know if your fuel improves with the new (better) plugs...
 
#19 ·
QUOTE (bloodninja @ May 24 2009, 10:34 AM) index.php?act=findpost&pid=237969
?

I've never seen a gas station that doesn't use up to 10% ethanol blend here. I just thought it was required to help with emissions or something.
(Long time listerner, first time caller)

It depends on the state's laws. I can only speak for my region, but I know Missouri has a law that all gas must have at least 10% ethanol; whereas Arkansas does not require any ethanol, but does require that any pumps that have ethanol must be clearly marked so the consumer will know what they are buying.

For the record (and this is just my opinion from what I have read) I would recommend putting as little ethanol in your vehicle as possible. You will get less mpg and it will erode your plastic/rubber parts (fuel intake/fuel pump, etc) quicker unless you have a car made to use ethanol, which Hyundai doesn't make to my knowledge.
 
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