Was having a go at trying to change the Spark Plugs today but can't for the life of me figure out how to undo the clip that attaches the airbox to the hose - looks like you need some kind of special tool to get it on and off.

http://imgur.com/a/w2Mck

flat screw driver in and pry it apart

you need new clip afterwards

this is how we do it

Cheers, that worked perfectly

Although was still a struggle to get the box off, but got there eventually.

Took a while to also get the plugs off as the leads were so short and so tightly clipped into their separators, I don't have a blower but used a Dyson to vacuum around the engine and in the 4 bays.

I noticed when looking down the bays with a torch that the 1st spark plug, on the left appeared to be a tiny bit rusty at the very bottom, the other three looked fine, so I sprayed a little PlusGas into each bay and thought I'd wait an hour before turning the spark plugs.

I've read that it's a good idea to turn the plugs 1/8th tighter first to crack any corrosion that might be in the threads and then 1/4 turn looser and then allow the PlusGas to work it's way through the threads overnight if possible?

I'm in no hurry, I'd rather take things slow and steady.

I wait an hour after spraying the PlusGas and then decided to give the plugs a little turn, first tighter and then looser.

Interestingly I tried to tighten all the spark plugs a tiny bit without using much force before loosening them a quarter turn and the only plug that tighten easily was the first plug which I said appeared either brown or a little rusty at the bottom.
Anyways I've loosened all the plugs a little now and put in a tiny bit more PlusGas and going to leave that to soak overnight.

flisko said:

deeinlondon said:

Thread, length, diameter, gaping, etc all identical only - only difference is how quickly hot / cold the plug is.

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dunno about hot cold stuff, never bothered with that, someone else might explain what that does to car

Click to expand...

The spark plug has an "operating temperature".
This "operating temperature" depend on the way the plug transfers its heat to the cylinder head and has two goals :
* cleaning the plug ;
* avoid auto ignition.

If you change this "operating temperature", you will run into troubles :
* should you lower this temperature then the plug will not get well cleaned by the heat and you will have to change the plugs very often ;
* should you increase this temperature then the plug will generate auto ignition and knocking. The punto has an anti-knocking detector so you will not destroy the engine but it won't run as well as it should.

HTH

Did you buy the "correct" plugs, or are you trying the free "wrong ones" that someone was sending you?

bluejohn125 said:

Did you buy the "correct" plugs, or are you trying the free "wrong ones" that someone was sending you?

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I bought totally new spark plugs. Same ones recommended in the owners manual NGK DCPR8E-N

I was reading up on the issue of using Anticease paste, just about all Spark plug Manufacturers say they coat their plugs with an antiseize coating and it shouldn't be used on brand new plugs going in for the very first time -

most say the coating is designed to breakaway the first time you unscrew the plug, so it allows the plug to not stick to the engine

they only say to use paste if you're reinstalling the same plug as that coating would have come off then

http://ngkntk.co.uk/wp-content/uploads/2011/04/5884-Spark-Plug-Pocket-Guide-.pdf

" NGK does not recommend the application of lubricant to spark
plug threads as the resultant reduction of frictional forces at the
thread faces will render the torque charts inaccurate and over
tightening could occur"

So how do they look?

Plugs in order they were removed, first plug I think was much looser in the chamber then the other 3 and the only one with a corona mark.



http://www.ngkntk.co.uk/index.php/technical-centre/spark-plugs/corono-stain/

these were original spark plugs?

flisko said:

these were original spark plugs?

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Yes original - from the factory - 16 years old, 27,000 miles on the clock

So today I drove the car for the first time since changing the spark Plugs.

Went on a 7 mile drive in town to a near by lake - so stop and start traffic and maximum of 40 MPH.

On the journey to the lake the engine felt a little smoother in acceleration

But on the way back I stalled it at the traffic lights which is unusual and it wouldn't start first attempt. It did the 2nd.

There after I turned off the City mode which normally gives me much faster acceleration (a feature that is on the sporting models) but it didn't seem to accelerate as quickly as I was expecting. Felt like the computer fighting my input and was slowing me down.

One thing I noticed was my MPG figure on the trip computer - on the outward journey it started at 20 MPG but quickly got to 35 MPG which is normally about what I get around town (33 MPG to 35 MPG) but soon after that it went as high at 47 MPG. That is something I don't normally get unless I'm on the Motorway stuck in a 50 MPH zone.

I don't ever remember the car giving that high a reading in town in the 16 years I've had it since new.

Had half a tank of Shell Fuel in the car (regular unleaded)

I have recently changed the oil to fully synthetic and a new oil filter a few weeks ago but that only saw the car touch about 38 MPG at most in town, so now sure how changing the Spark Plugs has gone as high as 47 MPG.

Any thoughts?

Also I've heard that there's a way to reset the ECU to relearn it's mappings after a major component change like spark plugs?

city mode is for your steering wheel to become easier to turn, and there is no need for ecu relearn after spark plugs change

flisko you spoil sport,just when I was gonna have some fun!

deeinlondon, nice new oil of the correct grade is always a good thing but I think that the plug that is burnt & was not tight had been leaking compression gases for sometime which has now been cured helping improvements in your MPG.

I drove my car on the Motorway yesterday for the first time since changing the plugs - wasn't getting anything special on the way up the motorway but on the way back the Trip Computer went up to 58MPG - that is the highest it's ever read, ever.

I'd say previous record was 50 MPG driving at 50 MPH - this was 58MPG doing 70 MPH, don't know how correct this figure is.

Only other change was switching to Fully Synthetic Shell Oil few weeks prior to Change of Spark Plugs.

The averaging may take a few miles to adjust... but you'll have more experience with that. I'm not sure what you mean about the engine performance.. if all you've done is an oil and plug change then nothing should have changed significantly. Unless it was running badly before then an ECU relearn shouldn't be needed, but in any case I think you just disconnect the battery for half an hour - have a little search around.

There's always the possibility that if your plug leads are old and flaky they may have been OK before your work, and your jiggling has found a weakness. If something seems odd then you will have somehow changed or disturbed something.

Sounds like a success overall...

bluejohn125 said:

The averaging may take a few miles to adjust... but you'll have more experience with that. I'm not sure what you mean about the engine performance.. if all you've done is an oil and plug change then nothing should have changed significantly.....

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The ECU seems to have gone back to pretty much normal now, when I first changed the plugs I was getting super high MPG figures in town driving but the acceleration wasn't very good .. kind of like the car was running super lean.

Now the acceleration is there but with more normal kind of MPG figures in town, on my last trip, having said that there was 3 passengers in the car when I'm normally on my own, so may need to double check that.

Motorway trips are rare for me but I've got one coming up next Saturday so will check again the kind of mileage figures I get. But if something as simple as changing Spark Plugs can lead to such a huge improvement in MPG figures then might have to look into it for the two other cars in the house but they are 18+ year old Ford Fiestas and no trip computer to give any indication of mileage. And their drivers don't drive many miles either so not keeping much of an eye on the mileage figures.

2 extra people in a light car like the Punto will make a big difference as a percentage of weight, and around town slowing down and speeding up etc this will have a noticeable effect on MPG.

Just be aware that modern plug leads are often forgotten for years so need at least to be considered, I ignored mine for too long until I disturbed them and got problems.

What problems did you have?