front plug is black rear is white

[chas]

My front plug on 03 Ultra is running black and rear is white. Im getting a stutter running at 40 mph. Im running an improved stock map on power vision. When adding 3% fuel I'm getting less decel pop. Any thoughts? Thanks in advance

[rigidthumper]

I'd replace the intake seals & verify the injector wiring is intact.

[chas]

If the intake seal was leaking wouldn't it be more likely to run lean rather rich? Plug is not wet just blackened. If the injector wire was loose what would be the fix?

[rigidthumper]

Intake leaks, or bad injector connections, tend to give you one dark plug and one white plug. Given the age of the bike, my recommendation is to do both, since you're gonna be in there checking the wiring- the injector wires on early Delphi rubber mounted bikes tend to break inside the sheathing, usually somewhere between the pin and the harness next to the frame ( last three-four inches of wire). This causes an intermittent connection at first, and eventually leads to a complete misfire on the affected cylinder.

[Deye76]

How is starting and idle? Clean that IAC while you're at it.

[biggzed]

My 07 Road Glide was a victim of this. It broke right under where the MoCo had a zip tie on the wiring harness. Check those areas as well.

Zach

Intake leaks, or bad injector connections, tend to give you one dark plug and one white plug. Given the age of the bike, my recommendation is to do both, since you're gonna be in there checking the wiring- the injector wires on early Delphi rubber mounted bikes tend to break inside the sheathing, usually somewhere between the pin and the harness next to the frame ( last three-four inches of wire). This causes an intermittent connection at first, and eventually leads to a complete misfire on the affected cylinder.