Dud spark plug

[Monkeythree]

Just fixed a bit of an odd fault on my S2. I got it out of hibernation a couple of weeks ago and it wasn’t running brilliantly. I thought a quick blast might clear it but made it worse and it settled down to running on 3 cylinders. I quickly figured out it was no. 1 but my inductive timing light was telling me I had a spark and I jury rigged the injector to confirm it was firing. Did a compression test just in case something major had exploded. It hadn’t, it was all fine. Turns out it was one of my fancy pantsy Denso Iridium spark plugs that had decided it didn’t want to be a spark plug any more and had chosen a new life as a pineapple. So after less than 500 miles it’s gone in the bin along with it’s 3 brothers and I’ve ordered some Bosch ones.

 

[Cater_Racer]

Wize choice

 

[Mike_Pollock]

Just be glad it didn't fall apart, known 2 of them to......

 

[Monkeythree]

Just be glad it didn't fall apart, known 2 of them to......

The Denso ones specifically?

 

[MJL944]

I had Denso Iridium spark plugs fitted in my S2 back in March 2013 - they're still there, only 7,500 miles later, but working fine (new Beru leads, dissy cap and rotor arm were also fitted soon after).

However, just today I asked my excellent local garage if they could fit top quality plugs on my (wonderful) daily 2007 petrol Fiesta as part of a quick service - iridium plugs were mentioned but we agreed that was a bit excessive. On picking the car up the mechanic told me he'd fitted top notch Bosch plugs and then told me, "we don't fit Denso Iridium plugs anymore as we've had more than a couple fail and each time it's been the ceramic coating that has cracked, so we're staying clear. It's Bosch plugs wherever possible for us now".

This issue has been discussed on a few occasions on Porsche boards in the past few years - the general consensus seems to be that someone is counterfeiting Denso plugs and they've got into the general supply system in the UK - probably through cheap online sellers.

As I said though, I've had no problem with mine, so they get a thumbs up from me, but I'll probably choose another iridium brand next time!

 

[PSH]

I fitted Iridium plugs early on in their existence, I can't remember the make though, since Denso invented them it could well have been that brand, I just can't swear to it. Anyway, number 2 plug failed, a lump of ceramic broke away resulting in damage to head, piston and number 2 bore. This was the morning of a dyno day at silverstone, started car to go and got the tap,tap sound just like you get from stuck lifters. This cleared within a few minutes and I thought nothing more about it, car ran fine although had a slight hesitation under full load. On the dyno the same hesitation was still there and thus the operator only did the one power run. If only I'd known that this was purely down to a failed plug I'd have replaced it. Car still produced the 368bhp as it had some months before when set up by Wayne. It took a while before I found the broken plug, other than the hesitation under full load (I rarely use WOT) the car ran fine. It was much, much later when stripping the engine down that we discovered the damage and also that the air filter insert had disappeared into the engine too. All sorted now, oh and I'm still on Iridium plugs but I only use NGK brand now..

Cheers

Pete

 

[blade7]

It's not just Denso plugs that are fakes, I only buy plugs from the bigger suppliers that state they are official dealers of the genuine parts.

 

[vitesse]

I've always used Bosch Supafour plugs in the 924S's since I initially found I could use them in a Rover Vitesse Turbo Sport even though not listed for the model & previously in both Honda V6 Vitesses.

They last over 25k miles & come out when changed looking almost like new

 

[blade7]

I cross referenced the part number and found much cheaper plugs for the turbo listed for a VW.

 

[zcacogp]

Turns out it was one of my fancy pantsy Denso Iridium spark plugs that had decided it didn’t want to be a spark plug any more and had chosen a new life as a pineapple.

Well that's nice. It was warm and sunny over the weekend and if I'm sitting in the warm sunshine having had a decent meal and have to choose between a pineapple and a spark plug then I tend to choose the pineapple. It makes a nice refreshing dessert and is particularly good lightly flambéed with rum and sprinkled with some freshly shaved coconut. Add some brown sugar if the pineapple isn't that ripe (which is a detail I don't think you added Tom.) I'm sure you will all agree that a spark plug just doesn't quite cut it in those circumstances.


Oli.

 

[scam75]

Yes spark plugs are murky water these days. Echo what Blade says about being very careful where you purchase them from. I've only ever used Bosch or NGK on my turbo and both have been excellent. In fact CP4L doing the Bosch ones just now for £1.92 each delivered (less any of the frequent discount codes, I used MAY12 which brought unit cost down to £1.69!). Seems a no brainer so have ordered some. My current NGK's have lived about 20k miles and still seem fine but must be nearing time for a swap over.

Stuart

 

[Monkeythree]

Yeah I got Bosch WR56 from CP4L for less than 2 quid each. Being part of ECP I assume they only buy from OEM suppliers. Fitted them yesterday and the car is running like a dream. Not only fixed the misfire but running better overall. Pretty convinced that the Denso ones I had were cheap chinese copies.

 

[Robin]

I have had an intermittent misfire on my 356C ever since I renewed the Bosch spark plugs, distributer cap and leads set. It seemed to clear and run normally for a while and then the misfire returned. I have removed the new plugs and put the old Bosch WR6BC plugs, which had only done 2000 miles, back in and now the engine runs well with no trace of misfire. I am suspicious of the new plugs which have "Russia" stamped on the side of the plug base.
I have always used Bosch plugs but am a bit wary and may look elsewhere for the next change.

 

[scam75]

My old and new Bosch plugs have RUSSIA stamped on them. Not had any problems.

Stuart

 

[zcacogp]

Yeah I got Bosch WR56 from CP4L for less than 2 quid each. Being part of ECP I assume they only buy from OEM suppliers. Fitted them yesterday and the car is running like a dream. Not only fixed the misfire but running better overall. Pretty convinced that the pineapples I had were cheap chinese copies.

Edited that for you Tom.

Out of curiosity, where you did you buy them from? I'd guess that it was somewhere smaller as I doubt that the bigger chains buy anywhere other than the manufacturer or one of their tier-one distributors.


Oli.

 

[Sy924]

Famous last words... but never had any problems with NGKs...