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2002 Forester L 5mt
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219 Posts
Discussion Starter #1
I posted about a month ago about a hesitation problem I was having with my 2002 L, 2.5, 5spd MT. Initially it was hesitating on light acceleration between 1300-1800 rpm, intermitantly. I didn't manage to find the problem, and the hesitation is somewhat worse, from 1000 to 2200 rpm now, sometimes worse than others. The car starts right up, idles smoothly, pulls strong above 2400 rpm, and is steady at speed. The car has 73600 miles, and gets 23-24 mpg in town.

The plugs have 14k miles on them, and appear normal, (light tan).

I inspected the coil with a multimeter, and this is what I found...

The primary side between terminal 1 and 2, and 2 and 4 should read .73 OHM +/- 10%, my reading for both was nothing...open circuit.

The secondary side should read 12.8 OHM +/- 15% between the #1 and #2 cylinder terminals, and the #3 and #4 terminals...I got 13.98, and 13.70 respectively, a little high, but within spec.

The shortest spark plug wire should read a mimimum of 6.24 OHM, I got < 4OHM.

I thought this all seemed off, so I checked again, then checked again with a different multi-meter, and got the same results all over.

The plug wires aren't OEM, the terminal on the #1 of the original set broke at 33000 miles. I was out of warranty as far as time goes, so I replaced them with a set from NAPA, (Belden max).

Questions...Is the coil fried, or did I read it wrong? Could it work with broken or burned out primarys? Did the low resistance in the spark plug wires damage the coil? Should I find a new one before I end up stranded beside the road? Is this even the cause of the hesitation problem in the first place?

Any ideas?
 

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2010 Forester
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174 Posts
It sounds like you have a break in the primary side in your coil. When the car is running, enough voltage may be getting across the break to induce power in the secondary side. Over time it will get worse as the the spark across the gap makes it larger. I would recommend replacing the coil.

I had this same problem in an older car and the case for the coil had cracked allowing moisture inside that corroded the wires.
 

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02 Forester L (sold) Manual
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1,221 Posts
Our Impreza had a similar problem that plagued me for some time, but new wires fixed it. However, the coils on these aren't known for their durability. The plug wires could be the culprit depending on the quality of those replacements. I'd get NGK's the next time around. I think you're looking at the right things, just not sure which thing to select first since I'm no good with electrical readings.
 

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2002 Forester L 5mt
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219 Posts
Discussion Starter #4
It took a while, but I found the problem:Banane17:

The #4 spark plug wire was bad. I put on a spare from the old set, and the car is fine!

Now here is the question...what would be the best brand spark plug wires to replace them with? The OEM Packard set broke at 33k miles, and the NAPA set seems to have only gone 40K more. What do you all run?
 
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