Seasons Greetings to one and all

A couple of weeks ago, towards the end of a 50 mile run, whilst accelerating very hard in 3rd (at approx 4,000 rpm) the engine stuttered slightly (not what you'd call a full on missfire), I instantly lifted off and changed into 4th and it didn't do it again.

Then yesterday, when just as I was nearing home (again after a 50 + mile run), the same thing happened again except this time when I changed up into fourth it carried on stuttering when I reopened the throttle, but stopped as I backed off and cruised the last mile to home.

Today I've gone out to see if I can see what's wrong and it's now stuttering all the while (in any gear) when the engine is under any load and the engine check light has come on............

The car starts and ticks over fine, hot or cold. However the stuttering starts as soon as you increase the throttle as if it's suffering from a weak spark or fuel starvation (currently 10 galls of Vpower in the tank). Fuel consumption has been rock steady and there has been no noticeable drop in performance, similarly there have been no nasty noises or emissions.

Anyone any ideas where to start looking????

Car details:
02my WRX
Green Cotton Filter
Samco Induction Hoses
Decat Up-pipe
Sports Cat Down pipe
Decat centre
WR Sport rear box
Walbro fuel pump
ECUTEK remap
all fitted 10,000 miles ago (no problems until now)

 

could it be the plugs? ignition coil packs (if yours has them) or maybe just over boosting?

 

Dito same here. Now my check light is on will look at that tomorrow. Funny feeling its over boosting.

 

Thanks for the ideas so far, sorry to hear you've got a similar problem AntiLagger.

I don't think mine's down to over boosting because it does it from tickover as soon as you put the engine under any sort of load.

 

get mine from 3200 and up

 

easy way to find out if its your plugs

unplug 1 lead at a time ie unplug no 1 then turn on engine if shutters durrasticly not that plug so put it back then try 2,3 then 4 untill not much difference in shuttering = damaged plug
then check in the dark the leads, switch ignition on with all leads in then look for sparks which indicate a broken lead,
im guessing its a plug or lead