K series EU3 spark plugs

[StevehS3]

From the factory my engine (standard 1600K 120hp) was fitted with NLP100290 plugs. I have done one plug change a few years ago and fitted the same. I altered the gap to 0.9mm and they have been fine.

This time I fitted NGK BCP7ES from a reputable supplier. I didn't like the feel of how they tightened down and I noticed the plug cap was a bit more proud than before. The gap was between 0.8 and 0.9mm so I didn't touch it.  A test drive revealed the car hesitated on acceleration. I swapped back to the originals and all good. I thought these were the recommended plugs? I will get another set of the original type but any thoughts (out of interest).

[Jonathan Kay]

Private Message sent,

[SM25T]

Shouldn't there be an R in the part number ?

[Adam Godfrey]

As SM25T said, I fitted BCPR7ES to my 1.6k series and it is running fine.

[revilla]

Yes the wasted spark needs the resistive plugs e.g. BCPR7ES. That's what I was running my VVC on. However, after the head work I did to improve flow, I started getting a misfire when the engine was only partially warmed up or after a long coast down. There was a place on the way to work that was a long downhill slip road off a dual carriageway to a roundabout and it often dropped a cylinder while waiting at the roundabout. After trying lots of things, including new coil packs and new plugs of the same kind, I suspected the plugs were just running too cool and fouling, so I tried BCPR6ES instead just to get them hotter. Not had a single incidence of the problem in the several years since (it was happening once every two or three drives).

[StevehS3]

I thought I read that the R was purely related to interference suppression but obviously not as my car won't run properly with them. I will order some more NLP100290 as supplied with the engine from new. Many thanks for the replies. 
Steve

[revilla]

By the way, yes I have noticed the same as you mentioned about the plug caps sitting higher with the NGK plugs. I'm not sure if they are slightly longer in the body than the NLP100290s but the caps on the two cylinders that don't have to coil packs on top of them do seem to sit proud of the cam cover and don't look as though they would seal to keep water out in the way they appear to be designed to do.

 

[StevehS3]

Yes that did look rather strange. They don't completely seal with my originals but the NGKs looked about 5mm high on the plugs without coil packs. This did make me wonder if the coil pack ones were pushing too hard on plugs when fully screwed down. Separately, the centre electrode is a completely different shape - more like a pin shape on my originals. 

[revilla]

The different electrode shape is because the NGK plugs have copper electrodes whereas the NLP100290s are double platinum (they have a platinum pin for the centre electrode and a small platinum pad bonded to the earth electrode. The NLP100290s are more resistant to spark erosion and should be good for 90K miles or so, where the NGK plugs will need replacing more frequently and the plug gaps will tend to increase over time. A couple of people told me that a K Series seemed to run more sweetly on the NGK plugs than on the original platinum plugs. I have to say I could see no reason why this should be the case but I thought I'd give them a try and they did seem to run very nicely - although it could well be that I was just seeing what I wanted to see and imagining the improvement!

[StevehS3]

Well if they last that long they are nowhere near ready for changing! I am certainly very happy with them. Thank you for all the info.