acr2001

My 05 only has 27k on it, but the manual says to change the plugs after 5 years regardless. Should I bother? Can anyone explain the thinking behind that?

My car does sometimes start up bad but I'm not sure if it's plug related. It doesn't take any longer than usual to start, but every so often when started it's a little shaky for the first 1-2 seconds like one of the cylinders is taking a moment to fire. After that there's a clicking noise for about 4 seconds that fades away. Happens on both hot and cold starts, but only about 25% of the time. No check engine light.

LILBENZ230

I thought originally that we had the same start issue, only my car did it on cold starts only. But mine has pretty much resolved itself with no action on my part and it never did it on hot starts anyway.

I would change them per the recommendation. 27,000 miles is low for a car that's been on the road for 5 years. Sometimes cars that are driven the least have the dirtiest engine components.

aac85

my 05 only reached 18,000 KM just today.

LILBENZ230

Highway miles are better than city miles, thus a car with less miles doesn't mean it is in better shape. I drive my cars into the ground. I'm at 60k on my 05 and it had just 25k when I bought it last July.

acr2001

Originally (I thought) my problem was only on cold starts, but the engine proved me wrong.

I just pulled a plug and to my untrained eye it looked pretty good. The insulator was still pretty white and I could still see the platinum on the ground electrode. Really not sure if I should replace them for over $100 in parts.

Glyn M Ruck

Changed my plugs at 45,000Km - 4 years. Made a big difference to stable idle & slightly spluttery cold starts. It all depends how long they run per trip in the self cleaning range. If you do a lot of short trips then change them. They can't be cleaned other than a 1000Km drive once fouled.

Jack_2001C240

I changed the spark plugs on my 2001 C240 in 2007. Only about 25,000 miles at the time, but the plugs were 6 years old . The car sometimes idled roughly, and most of my driving at the time was the hard New York city stop and go type. The new sparck plugs and fuel filter solved the rough idle problem.

I had the exact same symtoms on a 1981 Buick Regal, 1990 Honda Civic, and 1990 Toyota Celica with rough idle and hesitation during acceleration. Each time the problem was solved by installing new spark plugs, wires, distributor cap and rotor.

acr2001

Ok fine you guys convinced me. I'll let you know if I notice a difference. The idle is definitely rougher than it was when I bought it, but you can still barely feel that the engines running!

skittles

i changed my plugs at 75,+++ miles. responds better but drinks gas more. lol. i switched from the OEM bosch to NGK iridium. from 32mpg to 24mpg(freeway). pretty big diffrence i know. i might switch back soon.. gas is going back up. lol.

LILBENZ230

It sounds like you could have a problem that is more serious than spark plugs.

slammer111

Spark plugs generally seem to last forever? Haven't changed mine in 6 years and car runs fine.

Utahkompressor

I just changed my plugs a few week ago with 54k on odo....it made a huge difference!
Engine runs smoother, more power and more MPG.
Still use the OEM Bosch.....only 5 bucks a piece and lucky for me M271 only takes 4.

BF_JC230

How hard was it to change them on the m271? I will be at the Dealer in a few days...maybe I should pick them up for our 2005...it has 44,000 miles and still gets a constant 29 mpg to the tank...

Thanks,
Jake

glocati

Lucky Dog...12 plugs for the V6 peeps. That's 3 changes for you M271-ers.

mtnman82

Jake, it's literally a 30 min. job on the m271. Only thing that could go wrong is cross-threading the plugs - just be careful (I turn the extension by hand until they're most of the way in). I think you also need a star socket to take the coil packs off, but that's it.

acr2001

From what I gathered its sooo easy on the M271. But I don't think the M112 is as too bad after i removed a plug today. Other than being 4x the price It cost me $125 for 12 NGK double platinum plugs (same ones my car came from the factory with). I really hope I'm not wasting my time changing the plugs at 27k. Book says to do it and I do drive VERY hard and very short trips, so Glyn convinced me to change em.

LILBENZ230

Very short trips are very hard on the engine.

Utahkompressor

It's very easy!
-pop the engine cover off
-unscrew the coil packs
-unscrew the sparkplugs
-put new one on
-DONE!!!

A 12-point socket worked just fine for unscrewing the coilpacks.....I know it's not the right way, but it worked

Glyn M Ruck

You have a problem - Are you sure the NGKs are correct heat range & reach?

splinter

Swapped mine at ~50,000 - about five years after its build date.
Squeaked something fierce upon removal.

Suspect the time interval recommendation is to minimize effects of the galvanic reaction between the steel plug and the aluminum head, and the very real likelihood of thread damage were the task to be delayed longer than half a decade.

The business end of its OE iridium plugs were actually in fine condition. The placebo effect of improved performance helped the attendant bloody knuckles heal a little more quickly.

BF_JC230

Was there any never-seize on the threads of the plugs? I will install a small amount on the upper threads when I re-install...I will do all of this work when I install the OEM block heater and pull out the threaded soft plug...

Thanks all!
Jake

wvadam

I was able to take the coil packs off using an 8 or 10 mm standard socket. they arent in that tight so you dont necessarily need the star torx socket.

Glyn M Ruck

As usual - you make an excellent point - my car had no perception of improved performance per se - but had been missing slightly on one cylinder at startup - you could feel the pulse at the tailpipe. This would clear if you revved the engine or warmed slightly. Dealer service computer (not STAR) threw up plug change required under the service plan so we did it & I kept the plugs that came out. They displayed some fouling - not bad. Start up splutter gone but no change in performance or fuel consumption. My daily to & from office cycle in traffic definitely had the plugs operating out of the self cleaning range too often. My car has Bosch OE plugs