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[Chuck Pryor]

09 SERG...  Since last November when I did my Fullsac upgrade (Stage II) I had been getting upper 30's to 40 MPG pretty consistently until...  the last month or so it's gone down DRASTICALLY. On my trip to Grand Canyon I noticed one stop it was more like 28MPG and I thought maybe bad fuel, wind etc... next tank was about the same. 3-4 tanks later and I'm like 25-27 MPG pretty consistent... no change in performance but the fuel mileage went to pot...
Typically when I used to fill up I'd have 225 remaining to emtpy... now it's more like 180 or so. Big difference.

 Called Steve, he seemed to think it might be an 02 sensor going bad... makes sense.  Called the dealer and explained... "without a check engine light we wont know what it is..."   Um, OK. 

Anyone experience this?

[Diamondback]

 

I agree with Steve.  One or both of the sensors is telling the TTS to run rich, very rich.

Should be fouling the plugs soon. 

 

[49445CVO]

I second the above

[2018_FLTRXSE]

Mine has been doing similar...

[grc]

................................. Called the dealer and explained... "without a check engine light we wont know what it is..."   Um, OK.  

.........................

Gotta love those incompetent nincompoops at your average Harley store.  Maybe if they hired someone who actually went to school for more than a day, and actually stayed awake, they could use a little grey matter and some simple diagnostic routines to track down problems without a big neon sign and an arrow pointing to a particular part saying "change this one".  Friggin' idiots.

The fact that you don't have a check engine light (you don't, do you?) doesn't necessarily mean you don't have any DTC's stored.  Somehow the Harley system seems to be able to set codes without turning on the light, which I didn't think complied with EPA rules but what the hey, Harley can get away with pretty much anything.  Anyhow, check for codes first.  Then it becomes a case of following a diagnostic routine.  BTW, there are other things besides the O² sensors that can cause what you described.  A bad temperature sensor can keep the ECM in warm-up mode (open loop), for instance.  That will definitely kill mileage.

If you don't have an Electrical Diagnostic Manual for your bike, it might be a good investment.  In the meantime, if the clowns in your dealership are really that useless, find yourself another shop that understands basic diagnosis.  Beats the heck out of just changing parts until you hopefully find the problem.


Jerry

[Diamondback]

 

[sadunbar]

Gotta love those incompetent nincompoops at your average Harley store.  Maybe if they hired someone who actually went to school for more than a day, and actually stayed awake, they could use a little grey matter and some simple diagnostic routines to track down problems without a big neon sign and an arrow pointing to a particular part saying "change this one".  Friggin' idiots.

The fact that you don't have a check engine light (you don't, do you?) doesn't necessarily mean you don't have any DTC's stored.  Somehow the Harley system seems to be able to set codes without turning on the light, which I didn't think complied with EPA rules but what the hey, Harley can get away with pretty much anything.  Anyhow, check for codes first.  Then it becomes a case of following a diagnostic routine.  BTW, there are other things besides the O² sensors that can cause what you described.  A bad temperature sensor can keep the ECM in warm-up mode (open loop), for instance.  That will definitely kill mileage.

If you don't have an Electrical Diagnostic Manual for your bike, it might be a good investment.  In the meantime, if the clowns in your dealership are really that useless, find yourself another shop that understands basic diagnosis.  Beats the heck out of just changing parts until you hopefully find the problem.


Jerry

   

What I like most about my area MOCO service departments is the condescending attitude displayed by the clueless uneducated service writers and service "techs".  The only thing worse than being bad at your job is to be bad at your job with an attitude.  

[Chains]

 

What I like most about my area MOCO service departments is the condescending attitude displayed by the clueless uneducated service writers and service "techs".  The only thing worse than being bad at your job is to be bad at your job with an attitude.  

That's for the dumb A$$ at the dealership

[Steve Cole]

Use DataMAster and just check to see if you have any codes. DataMaster will let you view and clear codes.