Better MPG after a B service and spark plug change?

[Silver CL55]

R230 350SL (2005)

Just had a B service at MB Hamilton which included both air and fuel filter change, also changed the spark plugs.

Should I notice much (if any) change in economy?
I'd say it apears a little sharper.

 

[DenniZ]

Oil change too?

Might be slightly better, but too variable to say with concrete evidence but I don't see why it would be any worst for a service.

 

[thecolonel]

most of the time, these items get changed before they become an issue and often changed at age intervals rather than mileage, so even less issue likely.

so in theory old spark plugs are less efficient at producing clean, sharp, sparks (due to element damage, carbonising tips etc) and old filters clogged with debris will allow less air / fuel through. By replacing spark plugs or regapping due to wear (not common anymore) and new filters will improve engine efficiency and hence give you better fuel returns than pre service.

 

[markjay]

Gone are the days when ignition timing, contacts gap, and carburetor needed adjusting...

You would normally feel a difference after service only if any items were overdue.

If replacing oil, filter, plugs etc on time, performance should not deteriorate significantly between servicing.

 

[A1EK]

ERm in a word 'No' my man. changing plugs really only improve the 'smoothness' in my opinion especially between gear changes as well as some plugs lasting longer then other like irridium.
Its always good to change filters as prevenative maintenance along with the oil and if anything you shoud notice a small improvment perhaps but nothing amazing. Its more peace of mind that its been done. You should be changing your oil as often as you can really, I do about 18K a year and change the oil at leat twice as its the life blood of your engine.

The only significant improvment i've seen in mpg is sensors when they start to go bad and changing a faulty thermostat that greatly helped with mpg.

As

 

[ItalianTuneUp]

The only significant improvment i've seen in mpg is sensors when they start to go bad and changing a faulty thermostat that greatly helped with mpg.

Which sensors?

 

[A1EK]

Which sensors?

This depends on what is faulty. If the sensors are okay then theres no need to change. However common sensors that need replacing are the font oxygen sensor in the exhaust that measure the gasses and adjust the fuel mixture I think via the ECU.

Also your MAF is part of the fuel mix too

If your car takes a while to warm up then it will use more fuel to reach the operating temp. The car should reach normal temp after about 10 mins. IF its still cold and theres no hot air through the vents it could mean your thermostat needs replacing

 

[ItalianTuneUp]

Thanks, I'm still at beginner stage and still learning about these cars, so I have no idea which sensors these cars have.

So an oxygen sensor in exhaust measures o2 in exhaust fumes and adjusts air/fuel mixture.

How many other sensors are there? The main ones to know about, at least.

I have real world experience of the thermostat...mine was stuck open and failing to warm the car, windscreen failed to demist & coolant temperature struggled to rise above 50C ish on a run.

And with airmatic there are ride height sensors for the self-levelling iirc.