Misfiring. Need Help! - VTXOA
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post #1 of 5 (permalink) Old 05-25-2016, 06:10 PM Thread Starter
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Join Date: May 2013
Location: New Jersey
Posts: 6
Unhappy Misfiring. Need Help!

Ok Guys, Here goes;
2002 vtx 1800C. 73,000 miles, bought it new. K&N air filter and Roadhouse Shorty exhaust installed 70,000 miles ago. Other than that, the motor is completely stock. Never had a single problem with the bike.... until now. Took it out for a short ride the other day and after about 5 miles it started missing really badly, backfiring and bucking like a wild horse. Got it home and replaced the stock iridium plugs with Bosch 4419's. (stock "deep" plugs had some fouling.) Took it out for about 15 miles. Same problem. Shut it off and restarted it and it ran fine all the way home. Back out for another 5 miles, same thing again. Back home, used induction timing light to check each wire. Every one showed an intermittent miss at mid to high rpm. Never has flashed a code on the FI light. Here's what i've done so far:
New Plugs.
Removed coils.
Inspected plug wires for breaks.
Trimmed ends of plug wires and reinserted them into coils.
Ground fix mods were done in 2003. Did them again.
Unplugged and sprayed contact cleaner on all connections under the seat, side panels and left engine cover. (Chrome one below the ignition key).
Installed new battery.
Rode 1/2 mile and it started missing again.
Ideas? Bad coils?(could both go bad at the same time?) Bad ECM?
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post #2 of 5 (permalink) Old 05-25-2016, 06:25 PM
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Location: St Charles, IL.
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How's you fuel mileage been lately? Check the oil see if it is overfilled or reeking of fuel. The 2002-2004 models with the internal fuel pump have a known fail issue with the Fuel Pressure Regulator or FPR.

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post #3 of 5 (permalink) Old 05-25-2016, 07:35 PM Thread Starter
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Location: New Jersey
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Performed the FPR check. No issues
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post #4 of 5 (permalink) Old 05-25-2016, 09:44 PM
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Location: Conyers/McDonough, GA
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2002----Check the 2 pin connector near the starter relay

2005 1300c Red, Mustang seat, HK 2.5 straights. Leds for safety-front & back. 181,111 miles of smiles

Last edited by Hans&Feet; 05-25-2016 at 09:48 PM.
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post #5 of 5 (permalink) Old 05-25-2016, 10:02 PM
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Double check your ground fix. Did you tighten the battery cables with a wrench? You cleaned those also, didn't you?
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