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Old 08-17-2006, 05:40 PM   #1 (permalink)
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Default Not firing on 3 and 5?

Strange problem, I'm having my engine rebuilt at the moment and it's missing on 3 and 5. Pistons are wet, plugs fouled but sparking. Injectors are ok (been swapped to other cylinders). Any ideas?
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Old 08-17-2006, 06:01 PM   #2 (permalink)
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Default Re: Not firing on 3 and 5?

bad coil check for power to the coil, then have someone crank it and check for a flashing ground on the other wire to the coil. if you have both then the coil is bad!
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Old 08-17-2006, 06:18 PM   #3 (permalink)
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Default Re: Not firing on 3 and 5?

Most likely coil pack, but possibly ECU.
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Old 08-17-2006, 11:02 PM   #4 (permalink)
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Default Re: Not firing on 3 and 5?

Are you sure its cylinders 3 & 5 that aren't firing? Have you confirmed that with a timing light? And are you sure you have your wires ordered correctly?


Quote:
Originally Posted by Stealth316
Ignition Timing
The firing order is 1-2-3-4-5-6, with each numerically-successive cylinder reaching top dead center (TDC) 120 crankshaft degrees after the previous one. Paired cylinders have pistons at the same relative position, such as both at TDC, but they are 360 out of phase, such as one is in the exhaust stroke and the other is in the compression stroke. Paired cylinders are 1-4, 2-5, and 3-6. Spark plugs are fired simultaneously in paired cylinders, during the compression stroke for one cylinder and during the exhaust stroke for the other cylinder. The spark during the exhaust stroke is wasted because the basically inert exhaust gas cannot combust.
3 & 5 should NOT share the same coil.
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Old 08-18-2006, 12:04 AM   #5 (permalink)
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Default Re: Not firing on 3 and 5?

Quote:
Originally Posted by Hannibalzero
3 & 5 should NOT share the same coil.
could not have said it better! if the wiring's correct, make sure that the PTU is okay, as well (diagnostics in the manual). you can actually swap coil locations (swap the primary's wiring on the bottom of the coils) to make sure that the coil itself is fine. If they are, then you're left with either the PTU or the less likely source, the ECU.

Good luck.
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Old 08-18-2006, 03:21 AM   #6 (permalink)
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Default Re: Not firing on 3 and 5?

Thanks guys, I've had a suspicion it's the ECU but hoping it's not. I'll try swapping the coils to see if it's that (yes, it is definitely 3 and 5, I checked the FAQ in here to make sure I had the right numbers before posting ;-) )
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Old 08-18-2006, 07:09 AM   #7 (permalink)
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Default Re: Not firing on 3 and 5?

Have you verified that there is no spark with a timing light?
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Old 08-18-2006, 08:17 AM   #8 (permalink)
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Default Re: Not firing on 3 and 5?

Heh! It turned out to be the cam sensor not fitted correctly. Running sweet as ever now Thanks!
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Old 08-18-2006, 08:39 AM   #9 (permalink)
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Default Re: Not firing on 3 and 5?

Yeah, that will do it.
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Old 08-18-2006, 08:31 PM   #10 (permalink)
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Default Re: Not firing on 3 and 5?

the sensor or the harness? Good find.
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