Several months ago I changed the spark plugs & wires on my '97 impreza outback 2.2.

 

Never really thought about gapping them... I have only really worked on diesels and didn't even know what gapping spark plugs was at the time.

 

Not sure if I put in pre-gapped plugs or not, but either way I don't want to mess anything up so I have two questions:

 

What is the spec for these? I got one of those little gap gauges but I don't really know what to do next.

 

-or-

 

Should I just go get a set of pre-gapped / fancier plugs? What's best for my car? When I got these I just walked into Napa and got whatever came up on the computer, cheap NGK's if I remember correctly..

 

 

Also, I should add that I have been getting slightly worse mileage, and minor missing when starting. Only other problem I know of is bad TPS sensor which I haven't replaced yet (do have the part though) which I was told will cause erractic idling and maybe bad mileage?

 

 

Thanks.

Edited April 9, 201015 yr by oldmuddysubaru

Most plugs should be pre-gapped. The standard NGK copper plugs, which I recommend are typically pre-gapped. It is good however to check them.

 

Gap for these motors typically range from 1.0 - 1.1 mm or about 0.040" - 0.044"

With such a high electrical charged current sent to the plugs, gapping a plug is not that critical. I suspect that your spark plug wires may be causing the occasional "miss," if they are old.

 

Best to replace with high quality wires, either Subie OEMs or Bosch. Not the cheapie "house brand" wires sold at parts stores. The cheapies just don't work well or for long in a Subie.

NGK wires are good as well.