when im on full boost(1.1bar) & full throttle i seem to be misfireing this is the only time it will misfire,as its fine on light throttle & cruising. Plugs are fine & gapped @ .65 & also the coil packs are in decent condition. i have installed a polar performance chip & was wondering if this was caused by over fuelling?

 

Hmmm. Obviously the PP chip is at 1.1bar (16psi) with a fuel cut at 1.2bar (18psi) Plugs are perfectly gapped, so I'd think it was your coilpack/s. Thing is they may look okay, but it only takes a tiny almost imperceptible fracture to arc the spark away from the tip.

How old are your plugs and coilpacks? When were they last replaced, etc.?...

 

had same problem and it was my plugs. when did you last check the gap?

 

ok,it was a coil pack causing the misfire even tho id checked & found 1 with a slight fracture i taped it up but this didnt work so i replaced the damaged coil & the car runs like a dream. I can remember the last time it felt as crisp & sounded as nice.
Also it made 272bhp on the rollers with boost wound down to 1.05bar to avoid the misfire this is when i found the result of the coil pack so after replacing that item the boost was wound up and ran beautifully. Thanks scott.t for your help through e-mail as well. Im more than happy with the result.

 

Can coil packs cause a misfire on light throttle as well?

How much would it cost to replace it?

 

im not sure,i suppose it depends on how damaged they are, theres some on e-bay £195 for 4

 

Not sure how bad they are, i need to check em but the misfire has always been there tried a number of things to sort it but now it's effecting the boost

 

tempramental things mate, how strange is this....my old ecu chip ran fine,no misfires or anything. then i fitted this polar performance chip and it started misfiring. It was the coil pack yet it had been broken all along strange how it would run one ecu fine but the new ecu seemed to find all the defects in my ignition. good tho cos nows its fixed and running crisper than ever...i love it.

 

im also going through the same problem as rob73 misfire at high boost, im running the polar perfomance ecu aswell,tried new spark plugs gapped to 0.65 & cleaned out & checked all boost hoses without success time to start changing coil packs

 

thats it matey,tbh i was surprised by this outcome at what a devastating effect on performance a tiny little crack in the coil can do. Ive learnt something its been a good day!

 

Coil packs can do any number of things depending on age/strength/damage :
From a realy bad misfire at idle through to misfire when cold, misfire at light throttle and misfire on-boost.
Raising the boost highlights the problem as the extra air/boost blows the spark out due to it being a weak spark.

I've got quite a number of emails over the last 6 years relating to misfire/coilpack issues......it's the bain of my life and becoming more so as the cars get older.

They don't always have cracks either, although cracking is a good sign their fit for the bin.

When people finally put hand in pocket and get coil packs the response is always as Rob decribes above i.e car has never run so smooth.

Not all cars have this problem, the majority work fine...just some need a little more attention when pushing the performance on from the stock levels.

I'm just glad you got the result you wanted Rob, 289BHP is not bad for a WRX Auto eh !!!

 

Mate, what you've said there about the misfire on all 3 things (boost, light throttle & when cold) im experiencing that now is it a good sign i need to dip into my pocket for new coil packs?

 

Yep, when you pull them out they will probably look like this :

 

OI Scott...have you been in my garage? that loos just like my old one! Thanks again for the help fella,im more than happy! it feels like a new car