My garage just informed me that my 94 WRX is misfiring when cold and that it will eventually need a new coil pack.

It doesn't do it when its warm / hot - (thank god )

But I've got a Power Test on Saturday at Surrey RR, and If my car decides to start misfiring when hot aswell, how if at all, will this effect my results?

 

power would be down etc..

you need to replace all four coils at once on that year btw..

Simon

 

If its misfiring when cold, how long is it likely to be till it starts doing it all the time?

Why does all 4 need changing at once - your the expert!

 

Only 1 of my coilpacks was shot when I checked them all, the others were perfect so I doubt you need to change all 4!

 

From experiance they expire due to heat cycle damage all at the same or similar time.. sometimes the tips go brittle and snap off and they break down inside and still look perfect.
At low standard boost levels it is less noticable and usually shows up on cold running as you mention. I would change as soon as possible as it is mostlikely missing or causing a weak spark most of the time you just don't notice the slight reduction in power.

If you replace one you will probably solve the cold misfire.. but if none of the tips are damaged it is a trail and error thing changing it around to find the culprit.. you will find that you fit it to a cylinder that is not causing the misfire when cold and straight away it runs much better.. but you still have the misfire.

Diddys maybe an exception to that rule but I suspect if he replaced the other 3 he would notice an improvement in smoothness.

I think Mark @ Lateral Performance stocks them.

Simon

 

oh and I usually find about 90k miles or 4years I notice them start to break down.. although on a standard car you can probably continue without noticable effects for a number of years.. I have changed to a 98 coil pack and HT leads this time just as an experiment as the spark was too weak to hold at 1.7bar on the set of standard coilpacks I was running.

Simon

 

1.7 bar is SLIGHTLY different to running stock levels though JGM hehe!

 

yeah but I was answering with regard to standard boost level rather than my own.. at 1.7bar it was blowing out the spark on nearly new coilpacks

 

Do I have loss of power at the moment even though it's not misfiring when hot?

 

possibly yes.. if the spark is weak..

 

My car cracked the ceramic right down the middle on a plug, that wasnt helping!