Thread: 4A-GE MK1 Engine My very own "no spark" thread.
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Old 09-14-2009, 10:11 PM   #1 (permalink)
como
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My very own "no spark" thread.

Okay, so I've narrowed down the problem:
she ran great until I pulled the entire wiring harness and all of the body panels, windows, etc off the car.

So, I've been putting back in the wiring harness and decided that enough of it is in that the car should start and run- but she wont go.

I think it's down to my coil/ecu, though. I threw a sparkplug into the wire that typically feeds my distributor (right out of the coil), and grounded the outer edge of the plug- no spark when she turns over (which she does just fine, mind you) Now, to me, I'd think she should spark every time any cylinder was supposed to fire at that point- so lots... but I didnt get a single spark.

So I grabbed the multimeter, and checked the coil- it has 12v, so I know the inlet power is good.

This implies one of two things in my mind:
1) bad coil
2) ECU isnt telling the coil to fire

Now, I doubt its a bad coil, since it worked fine before, and I honestly didn't touch much wiring back there. This brings us to the ECU not telling it to fire- for all I know I toasted the ECU somehow. The ECU has three main plugs going into it- the two outer ones cause something to "click" inside the engine bay when I plug them in, the center one doesn't. Probably doesn't mean anything to anyone, but just an observation.

So, I'm pretty sure the problem is with the ECU, the coil, or something isnt plugged in.
Now, the only plug connection I'm unsure of leads directly into the coil, which makes me a little su****ious. It happens to be an identical plug to the one that the engine bay side vent uses, and I cant for the life of me find whatever the heck that plugs into. (anyone can tell me that'd be great); the wire with the same plug thats currently plugged into the coil leads into the timing cover, so I can't imagine its for the fan, it would make more sense to be a crank position sensor, which would make sense to be into the coil... but yeah.

What's next? I dont exactly have a spare ECU lying around
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