Tappet and spark plug analysis

coullstar · 23 Oct 2017

So had my car a few weeks now and done around 800miles or so.

I changed oil from what I believe was 0w-40 to Miller NT 10w-50.

The car has a noisey tappet when cold (lasts about 30sec) which the oil change has helped very slightly.

The car has used no oil and no coolant has changed in the time Ive had it. All oil pressures are spot on and car pulls fine other than a random misfire on cyl 4 which I cleared once and its never pulled up again.

On the way home on Friday after giving it some stick the car started juddering as if misfiring then cut out so I checked all oil/coolant etc and started it up again. Still lumpy and knocking slightly however it cleared up and I got it the 2min home. Went out later and checked for codes - nothing.
Car started fine and tool it for a run and nothing was amiss.

Pulled the plugs this weekend on bank 2 with the results below. No.5 did seem very slightly different but a gentle wipe and its exactly the same as the others.

Anyway would a sticky tappet cause the very slight difference to the plugs? From what I can see its all running fine, I do plan on getting the tappet looked at but I suppose Im just a little paranoid about this so can anyone see anything amiss?

Photos were taken immediately pulling the plugs and they are about 10k miles old inc coilpacks etc. No.4 & No.6 plugs were identical in colour if that's not apparent in the photos.

Sundayjumper · 23 Oct 2017

coullstar said:
...about 10k miles old inc coilpacks etc.

I was thinking "coilpack" all the way through until I got to the end ! The lumpiness & knocking sounded exactly like mine behaved when one of the packs gave up.

Maybe swap the coilpacks around and see if the symptoms follow, or of they stay in #5 ?

wasz · 23 Oct 2017

Coil pack is the first suspicion. I've had dodgy ones, and dodgy spark plugs even on other cars/

Marky911 · 23 Oct 2017

Number 5 sooted up so I'd definitely be looking at coilpack or plug even though they aren't that old mileage wise.

Did you put the coilpacks back in same cylinders? I'd have tried number 5 one on 4 or 6 and see if they then develop the problem.

Good luck.

Edit - I should have fully read Sunday jumpers reply. But yep that's the easiest and cheapest way of experimenting.

X51 996 · 23 Oct 2017

Might be stating the obvious but although the coil packs have only been on for 10k miles it's entirely possible one is faulty. They seem quite fragile on these - I guess exposed to a fair bit of heat (exhaust etc) and moisture. I think they've changed the design too over the years? Because they used to crack the casing if overtightened too.

Good suggestions though of swapping the coil pack around though. To be fair they're quite cheap to replace so if in doubt..?

coullstar · 23 Oct 2017

Thats my next plan of attack. Im going to run it for a little bit then check again and swap over the coilpacks.

I was more wondering if anyone had a sticking tappet that had similar plug colouring. It was sootier than the other two.

Clutch needs changed soon as well as it started slipping after repeated hard use. *****.

cheshire911 · 23 Oct 2017

Change of oil (and filter?) is good. I'd suggest change all plugs and coil packs - 10k miles over what period and in what condition? The coil packs get hot, water splashes on them. The plastic cools when switched off, then heats up. Repeated cycles results in cracks.Hence the suggestion to change all plugs and coil packs.

deMort · 23 Oct 2017

I agree that no . 5 seems to be over fueling .. but we are talking a small amount here .. i could also say that no. 4 looks to be on the lean side .

Its difficult to come to a conclusion from the pictures and a perfect engine can have slight differences in plug colours .

What i would say is how many people have had a single misfire that caused the car to cut out ? several yes but 1 .. hmm .. so thats a little strange .

CPS will cause that but its more of a regular fault and not a one off , CPS faults are normally heat related .

Tappet noise .. if we take it to extremes then the valve isnt opening far enough but the car would alter the fueling to compensate so i cant see that causeing a problem , reality and its a slight gap and wouldnt cause a problem.

Atm this is a one off so its a case of seeing if it gets worse .

No fault codes .. not even for a misfire means the car has not seen enough misfires to trigger a fault .. and it dont take many before it will .

For now and if there is a fault then i would slightly lean towards CPS or fuel pressure but there is no real fault to find atm if it now runs ok .

JS1500 · 23 Oct 2017

Graeme, coincidentally mine has just started doing something very similar. Hesitancy / misfire below 2k revs. mine hasn't cut out though. I suspected a coilpack...hoping that rather than MAF or something more sinister.

coullstar · 23 Oct 2017

Thanks, yeah I'm using it again this week to check so should get another couple of hundred miles done.

It's runs perfectly fine other than that one thing on Friday so not overly worried. Just wanted to check.

deMort · 23 Oct 2017

JS1500 said:
Graeme, coincidentally mine has just started doing something very similar. Hesitancy / misfire below 2k revs. mine hasn't cut out though. I suspected a coilpack...hoping that rather than MAF or something more sinister.

If you can read out the faults then it will say a single cyl misfire for a coil etc .

Single coil will often misfire when its wet or damp only .. or when washed

If its below 3k rpm and you have vario cam plus ( x2 solinoids ) then it can be the high lift tappet solinoid .

You will have a single bank of misfires recorded if its that .

JS1500 · 24 Oct 2017

Demort said:
JS1500 said:

Graeme, coincidentally mine has just started doing something very similar. Hesitancy / misfire below 2k revs. mine hasn't cut out though. I suspected a coilpack...hoping that rather than MAF or something more sinister.

Click to expand...

If you can read out the faults then it will say a single cyl misfire for a coil etc .

Single coil will often misfire when its wet or damp only .. or when washed

If its below 3k rpm and you have vario cam plus ( x2 solinoids ) then it can be the high lift tappet solinoid .

You will have a single bank of misfires recorded if its that .

Thanks for that. Haven't read the codes yet but will do...

Tappet and spark plug analysis

coullstar

Singapore

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coullstar

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