Hey Guys


My 05-06 Impreza 2.5


Started to miss on number 4,, So changed all plugs, Still the same, Thought coil pack changed it still the same if not worse...


Any ideas or common faults


81k
Not kicked about everywhere

 

Get a compression test done, if it's not the plug or coil pack it may be mechanical, burnt out valve or cracked piston, what was the plug like when you removed it? Is it a WRX or STI?

 

No.4 cylinder,good chance it's ringland failure on the piston.

Hope it's something more simple though Trickie.


Mick

 

Do these things just go without any breaking down for a bit first, never had a cel light on before ???


Just swapped coil packs over problem stayed on number 4.


plug is dirty with fuel on it

its a wrx

and always sounded sweet as

 

Sadly could be as merlin24.

 

I build alot of scooby engines and more and more 2.5's nowadays, but very rarely do I build WRX's, STI's are the most common for ringland issues. If the plug is wet with fuel it sounds like it's not firing, if you had a compression issue it would still be burning the fuel off, but dirty with oil/carbon. Try checking you have voltage from the loom to the coilpack, you should have a constant 12v and the ecu fires the injector via the earth side. You can also take another coil/plug and try fitting it to No. 4 and check for spark.

 

I have swapped coil packs still the same. Later today I will be checking the lead for breaks and the plug to the coil pack then will swap over injector.. failing that doing a compression check.

Thanks.

 

Not had time to swap over injector but have done a compression test


All 4 around the same 130 ish psi so does that rule out the bore on number 4 been the fault


put it back together just hoping it would of self corrected
reset ecu, still the same lumpy on number 4...

 

Injectors swapped over no change still lumpy on number 4 but no cel light. I dunno what else I can do.

 

Try a new plug lead...that's what mine was years ago.

 

Thanks for your reply.. these don't have plug leads mate.

 

Anyone else ? Cheers guys

 

Assuming you haven't had a cambelt change recently and a cam was timed wrong (unlikely to affect only one cylinder), the compression test didn't show issues, then I think you'll have to do a leakdown test to ensure that there really is nothing wrong with that cylinder.