hi all!!!!!! im new here but not to turbo cars but this has got me stumped i have a missfire under hard load more when on full boost in 3rd 4th 5th but once over 4000rpm its gos away and drives fine i have had new maf sensor knock sensor oxygen sensor all new boost hoses with 1.2mm bit in the boost line ecu reads no fault code the car is a my99 uk model with wrx05 intercooler hks dump valve powerflow from cat back .... any help please would make me a happy man again

 

Lots of new bits but no mention of a rather obvious thing to check - the plugs and coil pack?
JohnD

 

I got a very similiar fault with mine mate although mine doesnt clear unless i back off.Just changed the leads thinking that would solve the problem,but no such luck.
Hope you get it sorted mate before it costs you anymore.

 

im going to get at the plugs weekend. my99 so only one coil pack but had that checked. i think it could be plugs but before i got the car it had a full service with plugs less than 8000 mile ago cheers for your help i will post back and let you know how i got on. if it ever stops raining !!!!!!!!

 

Check the plug gaps. Should be 0.7mm.

 

hi mate.....
check the plug-leads are firmly pushed on the spark-plugs..
under heavy accelleration on my old my99 I popped off one of the leads.
might be worth checking...
Peppe..........

 

i had a very similar problem with mine but mines an earlier model. I relpaced the coil packs and it was fine again. Might be worth checking

 

i have the same problem was really bad but changed plugs and now it is very slight when it does miss. i have changed leads as well, my car is also a my 99

 

after looking at my boost i think it may be over boosting does any one know what the fuel cut is on a my99 it hits 16psi then drops to 14 psi is this right

 

Sounds a bit high. Standard boost on a UK 99my should be around 0.8 bar (12psi)
JohnD

 

mine boosts to 16 psi as well but mine is a rb5 wr sport (ppp)