Spark plugs - what a pain!

mbzclk

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Hi all,

Happy New Year firstly.

Right, I have a W208 230K (Engine is the M111.982)

Spark Plugs last changed 07/2008 - Mileage at 72,000

This car uses Iridium plugs as standard...

Mercedes EPC: A003 159 97 03 (NGK - IFR 6D10)

NGK Partfinder for Cars & Light Commercial Vehicles

-

I was going to replace these today car now at 92,000 miles but I am told these are long life plugs and do not need to be replaced for quite a long time. (until I get to at least 110K) - I guess thats a good thing as the plugs are approx £10 each

What do you guys think? I got one plug out but I have no idea...

Click Photo to enlarge


Click Photo to enlarge

The economy is poor (I think) so was going to replace the plugs

Sorry the pics are of poor quality but did not have my digital camera to hand only my BlackBerry.

Thanks all.
 
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grober

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My guess----- the plugs are OK unless you are experiencing a misfire. Poor economy more likely to be a problem with your MAF , Lambda sensor, engine temperature sensor or even a heavy right foot. Remember short journey+ cold weather is going to drastically lower your MPG figures without anything wrong.
 
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mbzclk

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It could be nothing....

Full tank gets me 300miles and the trip computer shows 24mpg (approx)

when I start up in the morning it gives the mpg figure at 9/10 then slowly rises up (15-17) if on A roads 40-50 plus then it will reach 21/22...

When on the motorway it will go to 26-27 and on a long run can get 33mpg...

Just seems that most of the time I get the figure in the low 20's

Is this right / normal?

Should the figure be so low when you first start the engine up?
 

flango

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Same engine as mine and similar mileage. Long life plugs are a joke, performance deteriorates rapidly after about 12k miles (sooner if car is driven hard). If it were me I would be changing them I do mine very year along with other long life items that are not really long life.

Changing them on that engine is a relatively straight forward job unless someone has over tightened them in the first place.

What mpg are you getting in the bad weather mine had dropped to about 23 mpg on local runs and 28mpg on motorway runs where it normally does 34 mpg

If you think there is a problem I would get it on Star and have a look at the normal culprits MAF, Lambda etc.
 
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mbzclk

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thanks ***, yep I have heard this before about the CLK 230K being around the low 20's and most people going for the 320, however whats done is done and I have to live with the 4 pot! think I will get a V6 or V8 next

flanaia1, thanks for your reply, do you use these same NGK iridium plugs? If I was to change the plugs do you think this would improve the economy - performance seems fine..?

The plugs will be from Euro Car Parts but it will be the NGK Plugs as stated from the Mercedes EPC so I assume its the EXACT same part minus the merc logo...!

Do you think it should be changed every 10,000 miles in that case?

I usually get most / all items done every 10K simply as it does not cost too much.... also running on Mobil 1 0w40
 
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flango

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yep I have heard this before about the CLK 230K being around the low 20's and most people going for the 320, however whats done is done and I have to live with the 4 pot!

flanaia1, thanks for your reply, do you use these same NGK iridium plugs? If I was to change the plugs do you think this would improve the economy - performance seems fine..?

The plugs will be from Euro Car Parts but it will be the NGK Plugs as stated from the Mercedes EPC so I assume its the EXACT same part minus the merc logo...!

Do you think it should be changed every 10,000 miles in that case?

I usually get most / all items done every 10K simply as it does not cost too much.... also running on Mobil 1 0w40
Yes NGK Iridium from Euro, thin I would get it hooked up to a Star first to have a look see whats going on and check there is no underlying problems.

I know I'll get flamed for this but it's my and our customers who know what they are talking about experience that Mobil 1 is not a good oil for this engine for some reason it does not run well on fully synthetic oil. I run mine on 10 -40w semi synthetic and it is smooth as silk, it's also a damn site cheaper which means you can change it more frequent.
 
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mbzclk

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What oil would you recommend? Castrol? Mobil 10w40?

I was under the impression Mercedes state the oil must be fully synthetic and 0w40.

Does anyone else have any thoughts RE the oil...?

Regarding STAR, the car has had a basic check and NO faults have been found, maybe this needs to be looked into more indepth (live data etc)

Also at the MOT it was fine with emissions....

It did have a bad manifold blow which has now been fully welded and a new exhaust manifold gasket fitted too, (was also a slight blow on a pipe in the centre that has also been welded) however I find the economy is still low compared to others (flanaia1)

Would a bottle of Forte Gas Treatment help?
 
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mbzclk

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also flanaia1 - first thing in the morning on the turn of the key, what do you get for your MPG figure when it fires up.

Mine is usually 9-11 and then it rises after a short time driving... Is this the same or indication of an underlying fault?
 

flango

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also flanaia1 - first thing in the morning on the turn of the key, what do you get for your MPG figure when it fires up.

Mine is usually 9-11 and then it rises after a short time driving... Is this the same or indication of an underlying fault?
Not sure as mine is a pre facelift model and does not have the fuel computer so all my mpg figures are calculated on full tanks brim to brim.

What you are seeing mirrors exactly what I see in our Audi which would make sense as the mixture would be rich to compensate for the cold temperatures ( just like pulling the choke out in the old days) then it returns to sensible figures

As for oil mines running on Quantum 10 -40w semi synthetic
 

Adam230K

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I had the C230k and I was getting between 290-350 (even got over 400 once!), I live in london so my average speed on any given journey is probably 20mph.
 
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mbzclk

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Never had 400 Miles, the best I have had is 350 miles on V Power with a mix or motorway and town, so maybe on full motorway I can get 400ish...

I asked a mate to start up his Mercedes from cold today and his Trip Computer displayed 22MPG from the turn of the key, it fell to about 16MPG in a few mins...

Mine on the other hand, turn of the key, starts up about 11-13MPG sometimes as low as even 9 in the recent cold spell and gradually works it way up to around 18-20MPG...

Im thinking it's now time to hook it upto STAR and see whats going on here...
 

markjay

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Just to say... that I bought MB-branded NGK Iridium spark plugs from BRABUSK8 and they were cheaper than NGK-branded anywhere else on the Internet...

Thanks Acid.
 
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mbzclk

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Hmm! I will have to speak to him in that case...

Thank you.
 

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