I got a TJ 3.5L auto. What are the consequences if I delay the spark plugs replacement from scheduled 100,000km until 120,000km to save some money? Car is at 99,000km at the moment.

Fuel consumption will get worse..:)

in another thread you were saying that my leads and spark plugs needs changing, as a result of random loses of power.

Can someone explain to me how spark plug plays a part in fuel economy? Aren't they only used for starting the cars? I am not very tech minded with cars.

Can someone explain to me how spark plug plays a part in fuel economy? Aren't they only used for starting the cars? I am not very tech minded with cars.

Spark plugs ignite the air/fuel mix in the combustion chamber to push the piston down to turn the cranksharft to propell the gearbox which turns the wheels. Only Diesels dont use spark in the 4 or 2 stroke process, they use intense compression and heat to achieve combustion.

Can someone explain to me how spark plug plays a part in fuel economy? Aren't they only used for starting the cars? I am not very tech minded with cars.

http://auto.howstuffworks.com/engine1.htm

spark plugs operate 1 out of every 4 revolution (in a 4 stroke engine).

you shouldn't have too many problems extending spark plug replacement out by 20k km.

like Ego said, you might use a little more fuel as you don't get complete combustion due to the slow deterioration of the spark plugs. it's not like at 100,001 km they'll stop working.

cheers,
.wook

id just do it, my plugs are expensive in the cressida because they are irridium ones, but IIRC magna ones are half cheapies and half irridium. Most itd cost you is $100 in parts... if your that tight up for cash id be worried

Can someone explain to me how spark plug plays a part in fuel economy? Aren't they only used for starting the cars? I am not very tech minded with cars.
That would be the starter motor you're thinking of... Spark plugs ignite the fuel/air mixture in each cylinder.

get all 6 replaced with iridium plugs at once, that way you dont have to think about changing the front (easy to get to) ones inbetween the magor service points.

i have all six iridium in mine - think it only cost me about 12bucks each, but i got a REALLY good price on my 100k km service costings.... (even though the car was at 80k km i got the magor one done for peace of mind)

you have to take the manifold off i do belive to be able to change the rear plugs - so its not just the cost of the plugs too, its a few gaskets too. and then time factor as well.

Please tell me Mitsubishi didn't make the rear spark plugs physically different and that the front/rear are the same, just that the reason for the different codes is platinum vs iridium :)

That would be the starter motor you're thinking of... Spark plugs ignite the fuel/air mixture in each cylinder.

He could have confused them with glow plugs.

glow plugs are used for combusting the fuel just the same as spark plugs do, its just heat instead of spark.

glow plugs are used for combusting the fuel just the same as spark plugs do, its just heat instead of spark.

No they Pre Heat the fuel before it goes into the chamber and the cylinder head. helps them to warm up and fire quicker.

http://auto.howstuffworks.com/engine1.htm

spark plugs operate 1 out of every 4 revolution (in a 4 stroke engine).


.wook

1 every 2 revs wook.

glow plugs are only used for starting a diesel. They help ignite the fuel/air mix in the start up process. After a diesel is started, it uses compression to create heat and then the air/fuel mix ignites by way of self combustion.

glow plugs are used for combusting the fuel just the same as spark plugs do, its just heat instead of spark.
No...

No they Pre Heat the fuel before it goes into the chamber and the cylinder head. helps them to warm up and fire quicker.
No...

A glow plug is used to pre heat the combustion chamber... Not the fuel.

http://en.wikipedia.org/wiki/Glow_plug#Method_of_operation

3rd paragraph down.

As above a glow plug will heat up the chamber to assist in cold starting. Some newer diesel engines do not use glow plugs, they run even higher compression. I can remember one of our old concrete pumps had stuffed glow plugs, the boss was too tight to get them changed so on a cold morning it was half a can of aerostart to get the old girl to fire lol

No, plugs in a magna fire once every 2 crankshaft revolutions or once every 4 cycles A cycle is a piston going either up or down from top to bottom or bottom to top.

You have 4 cycles
Intake
Compression (plug fires just before the piston reaches top dead centre)
Combistion
Exhaust

I had a Verada brought to me once with 170k on the clock, never had had timing belt, plugs or fuel filter replaced in its life. Still ran, was a pig to drive

Did the main service, the owner was of course surprised at the improvement

No worries about 120k's will really depend on when the last time your front plugs were done to be honest.

I have never really understood the policy of only doing front plugs, the manifold is not that hard to get off, personally I use platinum and change them every 50k or so. Over kill i know hut hey, sho cares

1 every 2 revs wook.

d'oh! yeah, once every four strokes, not revs.

FN BANG!!!!!!! ...... Quote: Chopper Read ..... Jk :D

It's tempting to cruise down to Melbourne while I'm off uni so you have give my car a thorough once over MadMagna lol If I did you would have looked after both the Mitsus I've owned lol

Consequence for delaying spark plugs replacement?


Just do them man, its not worth the risk...
Snapping a Johnson-rod just ain't worth the cost of plugs...

Just put some Bosch Platinum Plus in mine today and aside from what a pain in the freakin **** it is the keep the manifold out of the way and get the old plugs out, I noticed how much smoother and quiet she is at idle now. But maybe that was the oil and filter change I also did today. Anyway, this was the first spark plug change my Magna has had as far as I know and the old plugs had practically no build up or corrison whatsoever. The front and rear bank had the same Champion plugs so I guess they were all platinums. So yeah an extra 20,000 kays should be ok.

Please tell me Mitsubishi didn't make the rear spark plugs physically different and that the front/rear are the same, just that the reason for the different codes is platinum vs iridium :)

They are all the same.

The four stroke engine was first demonstrated by Nikolaus Otto in 18761, hence it is also known as the Otto cycle. The technically correct term is actually four stroke cycle. The four stroke engine is probably the most common engine type nowadays. It powers almost all cars and trucks.

So per cylinder you get 1 spark every 4 strokes and 2 rotations of the crankshaft

suck, push, bang, blow.

that is the easy way to remember the four stroke cycle....lol

The four stroke engine was first demonstrated by Nikolaus Otto in 18761Holy crap the CIA does have time travel. Bastards!!

The four stroke engine was first demonstrated by Nikolaus Otto in 18761,

so... looks like we'll have a while till we see this technology then huh?:bowrofl:

HAHAHAHA Just go and buy standard one $15 bucks for a set of 6......... YEAHYEAH Bag me out but i still save money and they are just as good. You pay out around 120 + dollars and Me over 3 years 15+15+15 = 45 Bucks :D And performance differance or Fuel consumption NILlol ... All I do is replace them every 30000 kays Big deal im still saving money and to be honest these normal plugs are just a little bit better as the tips dont burn out or clog up as much as the irdium

They are all the same.

Hope you are having a lend here.....

The rears are platinum plugs, mits specified that they get changed every 100k's The fronts are standard plugs and get changed at 40k's from memory.

Sadly Mits went through a phase of using Champion plugs for a while, I have no idea what came over them during this time.

Personally the only plug I will ever use in any car is an NGK, even my mower and brush cutter all have NGK plugs lol

Yes, you can use either term, cycle or stroke.

You can buy a set of six platinum Delco plugs to suit these engines off Ebay for $60 and change.
Screw in and forget for 100k kms.
Why the **** would you frig around with the rear plugs every 20k kms if you didn't have to? Madness.....

Regards, Andrew.

its like changing your oil with semi synth every 5000 k's

because its better than leaving it longer haha!

Hope you are having a lend here.....

The rears are platinum plugs, mits specified that they get changed every 100k's The fronts are standard plugs and get changed at 40k's from memory.You didn't read what I said. I said physically different, other than the different code and fact that rears are platinum/fronts copper - so I could just go and buy a set of 6 "rear" platinums.

You didn't read what I said. I said physically different, other than the different code and fact that rears are platinum/fronts copper - so I could just go and buy a set of 6 "rear" platinums.
They are physically the same. I run 6 rears in mine.

As Billy said. Cheers.

Holy crap the CIA does have time travel. Bastards!!

Ha HA HA - apparently the 1 is a notation

Sorry, I just calls 'em as I see 'em - I'm not paid to edit