Newbie Needs Help - Ignition Coil?

daffy · Post by **daffy** » Mon Jul 27, 2009 10:53 am

Hi...New here and need urgent help. I'm not sure how to diagnose the real issue.

I'm no mechanic for starters...

I think the ignition coil is not working for cylinder 4. I remove the spark plug leads from the ignition coil one by one and they all have arcing and the engine sputters...all except for when i remove number 4. No arcing. no engine sputter. I am assuming that my car is running on 3 cylinders at the moment as it is very rough and uses a lot of fuel. This happened overnight.

Is this the coil fault or something else not sending the signal to the coil? How can I tell? I want to buy the ignition coil myself and replace it but it is expensive and want to be sure it is the fault without wasting money.

Please help. Oh...It's an Impreza '05 2.5L.

AndrewT · Post by **AndrewT** » Mon Jul 27, 2009 11:53 am

Careful with watching it arc etc, it hurts when you cop a boot from that! I havn't but I know somebody who did, his teeth hurt for days afterwards.

It's likely that it's just a faulty lead. Make sure it's pushed into the coil properly, and try swapping it with one of the other three to see. Most likely you just need one new spark plug lead. You can also test that lead by taking it off and testing it's conductivity and resistance with a multimeter.

daffy · Post by **daffy** » Tue Jul 28, 2009 11:54 am

I had a 150K service and all the plugs were changed. The leads were tested. They (subaru service) even plugged the computer in and it showed no faults.

If I swap leads around won't that stuff the timing? Sorry, I'm not a mechanic as mentioned before so excuse my ignorance...wanting to learn.

If there is no arc coming from the coil, does that mean it's the coil? Subaru wants $480 + GST for the part and i don't want to buy it to realize it's not the problem.

YouTube · Post by **El_Freddo** » Tue Jul 28, 2009 11:18 pm

daffy wrote:If I swap leads around won't that stuff the timing? Sorry, I'm not a mechanic as mentioned before so excuse my ignorance...wanting to learn.

No worries mate - when you swap the leads, do both ends at the same time: EG: Remove lead 1, then remove lead 2,3 or 4 and put in place of lead 1, put lead 1 in place of the lead you took off second. Use a lead that will reach the spark plug which means you may only be able to swap 1 & 3 or 2 & 4 with eachother.

daffy wrote:If there is no arc coming from the coil, does that mean it's the coil? Subaru wants $480 + GST for the part and i don't want to buy it to realize it's not the problem.

What this means is that there is no earth for the spark to arc from the coil to the spark plug - also be very careful when doing this, I've been told that newer EFI vehicles have a high current arc that can do you some serious damage, if not killing you.

If there is no change after swapping the leads over for the problem cylinder, pull the plug out and check the gap - it could be too wide, no gap at all or there could be a bit of crap in there so no spark can occur. If the cylinder is good with the lead swap, but the cylinder the lead is on that seemed to be the problem is not operating - get a new lead...

Hope this helps

Cheers

Bennie

steptoe · Post by **steptoe** » Wed Jul 29, 2009 10:24 am

a safe option to test spark is to get a tool. It looks just like a spark plug with an earth clip spot welded to it. One type for normal ignition another for high energy ignitions. Most auto parts chains should be able to supply. Then doing the swap leads trick as Bennie explains may be easier . If you are lucky the leads and coil have numbers for the cylinders. Cyl #1 is front rhs of car, 3 is behind it, 2 is front LHS of car, 4 is behind it. Positions on coil likely to reflect same to avoid lead cross over. If you were considering a coil at that price (mate, I am sticking the EA motors) it may be better to have Subaru hook it up to their machine and diagnose.

bobbyjimmy · Post by **bobbyjimmy** » Wed Jul 29, 2009 12:02 pm

I've got a spare coil pack that works you can have for $50 posted to wherever you are.