paul thornton

I recently replaced the denso pk20pr-p11 spark plugs in my 4 wheel drive cossie with the recomended o71s(car is stage 1 with a t34) only because the densos had been in for about 2 years; the car then became very lumpy off boost but felt very stong on boost. ive ordered some new densos today but i have been advised that if the car runs like this off boost it means its running lean but other people have just put it down to the 071s being a crap plug anyone any ideas?

mechanic28

iTrader: (5)

would say 071 being crap!!it would have to have to be mega lean to run bad on idle

tabetha

The mixture cannot alter because of the plug unless the plug is misfiring, if so it will do this more under load/boost than anywhere else.
The advantage of the denso plugs is the lower firing curent needed and the better spark.
071's are not crap but not the best, I would put denso's back in, I run IK31 on my stage 1 2wd, with no problems.
tabetha