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No spark on one side of coil pack


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Trying to fix my sister's BF's car with absolutely NO budget...

 

1997 Legacy with a 2.2L motor.

 

Car ran rough intermittently, then bogged down at idle while in gear, then just died. He's replaced fuel filter, coil pack, and we just put in another ignitor with no change.

 

We get spark to 3 & 4, but not 1 & 2. We've traced wiring from the ignitor to the coil and it's good, but we can't seem to figure out which pin from the ECU goes out to the ignitor. (well at least we couldn't figure it out yesterday before my back forced me to quit)

 

Any suggestions what this gremlin could be?

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just out of curiosity (and to eliminate a possibility) have you tried swapping the plug wires around? (ie: pull 3 or 4 and try on 1 or 2)

 

might be odd, but it is possible the plug wires are bad if there is power going to the coil pack, but not producing spark at the spark plug?

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What I don't get is that everything I could find pointed to a bad ignitor. We swapped that out and nothing. He's replaced a whole lotta stuff, but no one can afford to just keep throwing parts at it.

 

We're trying to eliminate the possibility that it's a bad wire to the ignitor from the ECU, but can't find a decent diagram or pinout chart (that shows which pin on the plug is which) :banghead:

 

It seems as if the ECU is sending a signal to fire one pair of cylinders, but not the other. I don't have a manual, so I don't know if the ECU triggers the ignition off the crank or the cam position sensor. If it's one of these 2, how do we go about checking it with a test light and digital multi-meter as the only electronic diagnostic tools available?

 

Every time I think about it I want a LARGE beer! :drunk:

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The crank angle sensor runs the spark the cam sensor runs the fuel i agree with heartless check the plug wires i know its a stupid simple fix but about a month ago my friends impreza was missing on 1 and 3 tried everything then put plug wires from a junk motor on it and it ran great.

 

My second guess is something that happend to me is one of the tabs on the crank sprocket for the spark got busted off i assume a rock got thrown up into it (no covers).

 

hope that helps Rob.

Edited by subaruguru
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Check for proper power to the coil - there are two sides to the coil so there are two leads that have to be powered going into the coil pack. I'm pretty sure that's how it works. They might be powered off seperate fuses.....

 

Did you try a third ignitor? I've seen them fail where only half the coil would fire.

 

GD

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FSM pinout for the Coil has only 3 wires. One (yellow) is power with ignition run/start. The other two (Red w/green, Blue) go to the ignitor module through connector B22. It's a large grey 16 pin connector on the passenger side top o the bellhousing. Check those for continuity. Visually check the wiring for cuts/cracks in the insulation. Also check all the connectors (especially B22) for corrosion/dirt in the pins. Spray them with some contact cleaner to ensure cleanliness. Sometimes unplugging and plugging them back together a few times get's them cleaned up.

 

The Crank and Cam angle sensors can only be checked with an analog multimeter or Oscope. Doubtful it's either of those since the ECU would not see the signal it wants from those sensors. I would think it would not fire at all if that were the case.

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I think Subaruguru has the problem pinned down. I thought of the same thing myself when I read the post. When this kind of trouble happens the reluctor tabs for the crank sensor need to be checked. There are two sets of tabs and they each control a pair of sparkplugs. The firing is controlled through the ECU.

 

Here is a link that shows some good shots of the engine. Check out the 34th picture. It shows good detail of the reluctor tabs behind the crank sprocket and the crank sensor above it.

 

http://lovehorsepower.com/joomla/index.php?option=com_content&view=article&id=48:1995-subaru-legacy-outback-timing-belt-and-water-pump-replacement&catid=10:subaru-legacy&Itemid=64

Edited by Cougar
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