Symptoms of leaking intake seals with fuel injection w/02 sensors?

[HarleyFranco]

What would the sypmtoms be on these newer bikes with fuel injection and 02 sensors?

Reason I'm asking is my fuel milage started to go south bike still ran fine, idled fine.  When I pulled the plugs they were dark and sooty looking, not white like they always have been.

I found a loose bolt on the rear head intake and tightened it up.  Wondering if that will fix it or will I have to be replacing the seals soon?

Bike is an 2008 Ultra Classic.

Frank

[sprocket99]

The symptoms when the seals on my 07 leaked were loud backfiring and decel pop. It would also run lean. Check the seals for leakage before you replace them. With a hot idling motor, spray throttle body or carb cleaner on each intake flange where it bolts to the head. Do it from the right side and take care not to spray into the intake itself. If your idle changes you have a leak.

[longshooter]

Frank,

I think you have to check for leaks on the intakes and the exhaust. Any extra oxygen getting into the exhaust will be picked up by the 02 sensors. This will be an indicator to the ECM to fatten up the mixture in an attempt to make it equal your  AFR/Lambda setpoint. The ECM will continue to do this until the setpoint is reached and could account for the plugs being black and sooty. If both plugs were affected, you may also may to look for a common leak that would affect both cylinders.
IE: vacuum plug/line, MAP sensor/seal etc.

longshooter

[gabbyduffy]

         Funny you mention this,..... I had just gone threw the same problem. I could not even tell I had a problem..
         I'm running the (precision EMS auto tune by Revolution performance). ....I would have never known until I took my bike and put it on a dyno, The AFR was all over the place. I thought my ECM was bad or the tune was bad. Then I read on the forum to check my intake seals,..... I replaced the seals and it runs like a different bike, it made a huge difference. Good luck, Let me know if I can Help Duff. 

[HarleyFranco]

Thanks to all who answered.

I ran it to work this morning and will be able to see if the gas milage has gone back up.  Tightening the bolt I believe has helped but I still may need to change the intake seals.  Will pull the plugs and check them too.

Frank