Hi guys, I have been experiencing hesitation from cold, only for a few min's until warm then all is fine. I want to replace the plugs, I currently have 6's fitted, I had a remap in Feb and I'm now running 281bhp. The question is do I fit another set of 6's or 7's?

Could the fact that the MOT station left my motor running for 45 min's on tick over have damaged the electrodes as it only started the day after!

Thanks to those of you who responded to my previous thread, just want to get the right ones.

Martin.

 

as it has been modded i would go for the 7's

 

Definetly 7's,and its advised to set the gaps at 0.6

 

My car is on 6's and im running 444/442 @1.3bar , had my car on 7's and it had a misfire when cold changed back to 6's and it was cured. Richard Bulmer who originally mapped it told me his spec c runs on 6's and its pushing 500bhp.


Cheers Dougie

 

i put 7's in mine last weekend and it STARTED hesitating when cold! But there again my coilpacks are knackered now so that might have something to do with it! :doh:

 

i had a misfire when being mapped on 6's, mapper said go for a colder plug like a 7, problem sorted when he tweaked it

 

OK, thanks for your advice guys. I think I will give the 7's a try and see how things go. I guess its time to lose some skin off my knuckles again at the weekend

 

6 do the job for what you need if you are goin 350+ then you need to touch the 7's

jim

 

probably the maf playin up if its only happning when cold. is it not settlining well when on idle

jim

 

i have got new NGK Iridium BKR7EIX are these any good for my vers 4 red top sti ? cheers

 

i've been using these for a few thousand miles now with no issues, i found i got loads more misfires with the PFR7B's. Maybe just me tho

 

Try using the PFR7G

It's interesting that lots of people on here, over time, have had issues when converting to the 7B and have then gone back to the 6B.

We were advised by Prodrive back in the mid ninetys to use the 7G (gapped between 0.6 & 0.7) for all modded uk road cars & all jdm cars (modded or not) & have never had a problem with them.

Phil

 

Interesting point. My 93 wrx import had PFR6G's in it before i changed to
PFR7B's. I never knew there were PFR7G's, although i haven't had any probs with the 7B's, however i am running a reduced gap, i think it was 0.6

 

Hmmm, the plot thickens then. I am sure the MAF is fine it was only fitted in Feb by Bob Rawle before my re map and the idle is a steady 800rpm. This morning the hesitation had almost gone, maybe the warmer weather is making the cold start less demanding on the plugs. The 6's have only been in there a year and like I said it only started after being on idle for ages at the MOT. Getting confused now!

 

If your having problems with hesitation when cold, then it my be worth considering the coolant temp sensor.

It is not uncommon to have problems with this sensor & it can cause the problems that you describe when it starts to fail.

Phil

 

Mine runs on Racing 8's - hesitates a little when cold but they arent cold for long. Pick the right grade for your purpose. I'd say 6's will be fine for your purpose.