Peugeot THP - The importance of a proper spark plug gap.

Ever since my Peugeot 308 THP150 ECU upgrade (great settings from etuners btw!) there has been a continous string of misfiring (or 'sputtering'). And let's just say that its been REALLY annoying!

For a long time I didn't know what the hell to to do. Online I was sort of let into believing that it might have been a boost control valve issue. So up until a couple of days ago I was close to throw in the towel and call the mechanic to fix it. [This was initally because of a lack of boost under certain circumstances]

Then I accidentally stomped across an article at etuners talking about spark plugs. And as I went through the text I slowly realized that that's exactly what I expirienced; serious misfiring due to increased spark gap.

Link: http://etuners.gr/en/index.php?s=12&t=11

Using a "search blade" (I don't know the English word for it) I found that the gap was around 0.9-1.0 mm. which is waaay too far apart! Etuners recommended 0.65-0.7 mm. for ECU remapped engines. So I carefully tapped the spark plugs and guess what! It worked!! Now I have a smooth continous acceleration without annoying misfire...

Remove coil pack 

(image: http://behcw.blogspot.dk/2010/11/changing-spark-plug-on-peugeot-308.html)

- Gently twist from side to side while pulling.

- Use 14 mm. bi-hex to remove the plug. Remember to use an extender! The spark plug is deeply ressesed in the engine block! 

Decrease gap to 0.65-0.7 mm.

(image: http://etuners.gr/en/index.php?s=12&t=11)

- I used a torque wrench rated at a constant 23 nm.

You can find a great explenation at NGK's website:
http://www.ngk.de/en/technology-in-detail/spark-plugs/installation-tips/torques/

I wish Stellios had told me to check those plugs...! :-)