imprezabob

Hi, i have a 96 wrx sti which i have recently had chipped with an ESL chip and mapped at Zen Performance, unfortunately, despite a month before having changed the plugs (ngk iridiums) and a few days before replacing a couple of cracked coil packs for some decent looking used ones the car was misfiring a bit, obviously when they turned the boost up it made the misfiring worse and had to hold back a little with the boost increase. Over the next few days the problem got a bit worse so i replaced all 4 coil packs with new subaru ones and changed the plugs again making sure the spacings were all at 0.63mm - the old plugs were funked. For a day this seemed to have done the trick with there being no problems, for the last few days after driving for a bit the car it starts to misfire or judder in the lower rev range upto about 3k when the turbo kicks in it stops, it is also wavering a little while idleing, after a while it stops and is fine again..

I am thinking either the mapping is to rich in the lower rev range causing it to foul the plugs at low speed or possibly the boost related piping may been leaking, but this has been checked recently... the MAF sensor has been replaced since i have owned the car when this went the car displayed different symptoms.. any ideas?

6420Russell

hi im currently experiencing the same problem on my w reg turbo 2000 classic. but mine is every so often and not all the time like urs. i have a single coil pack and leads. is urs the same ? sounds like u have idividual coil packs, hope u get it sorted, if u find out wat it is let me know, im replacing parts one at a time starting with leads, done plugs about 1 month ago too, cheers Russell

STiFreak

iTrader: (4)

Pull the plugs and check if they are fouled again. If so, give them a clean with some brake cleaner and a old tooth brush. Make sure to note what the plugs look like when you remove them from each cylinder as this may give you some clue as to where the problem is.
Other possibilities are:
Earthing points are poor.
Damage to ignition wiring
Cam or crank position sensor dirty of faulty.
Injectors faulty or dirty.
... the list goes on.
Misfires seem to be one of the hardest problems to diagnose because there are so many possibilities. Best of luck.

Some useful information on this site:
http://www.aa1car.com/library/misfire.htm

imprezabob

thanks mate.. i think i'll take it to Zen again and see what they say

dj219957

has the fuel pump ever been replaced?

imprezabob

hi mate.. yeah i have a walboro pump on there which i got new recently. It definately wasnt a fake. the remapping also required 440cc injectors which i got second hand off a guy from Zen performance. Also had to fit a later MAP sensor.