[cealbrecht]

I've been noticing that my gas mileage has been plummeting on the highway. I remember a time when I was getting 45+ to the gallon at 80mph. Now I'm lucky to top 40. Today, I was riding through some twisties in the lower Adirondacks and found that the bike stutters when accelerating out of a sharp turn (left or right). I stopped to snap a couple of pics at a scenic overlook and the bike took more than 5-6 cranks to fire up (typically, she starts up in 2-3 cranks). I've tried all the easy suggestions...gas treatment for the ethanol, fuel injector cleaners, canisterectomy, and changed all my fluids and spark plugs.

I've never replaced the fuel filter or air filter. I'm guessing my next step is the fuel filter, the air filter, vacuum lines on the fuel rail, and possibly the internal fuel hose in the tank. Am I missing anything else, that may be easier than pulling the whole tank?

Patient's vitals are as follows:

Name: Tickets
Birthday: 2002
Age: 39,000 miles
Ethnicity: Silver
Typical meal: 5.5 gal of 93 octane with 10% ethanol and a shot of fuel injector cleaner.
Other: No farkles. Resides in a cozy garage. Battery is new. Right side mirror vibrates due to broken plastic tab. Some of the cover screws are missing, but she has enough to hold her together at maximum velocity.

She's getting sick, please help me save her.

Thanks,
Chad

 

[Cochinosucio]

I've never replaced the fuel filter or air filter. I'm guessing my next step is the fuel filter, the air filter, vacuum lines on the fuel rail, and possibly the internal fuel hose in the tank.
Chad

Sounds like you are on the right track, Replace the injector O-rings also...

 

[rowie]

You've listed what I would do - I think you're on the right track.

 

[jzeiler]

Typicaly a sharp sudden drop in MPG is due to a failing O2 sensor.

 

[Cochinosucio]

O2 sensor- Bosch 13475. Plug and play.

http://www.ebay.com/itm/NEW-BOSCH-OXYGEN-SENSOR-13475-FOR-BMW-1995-2003-/160783050536?pt=Motors_Car_Truck_Parts_Accessories&hash=item256f6aa728&vxp=mtr


According to search......

 

[cws]

I'd be trying a non-ethanol blend for a while and see if it helps. I ran 95 Ron with 10% ethanol for a few years, and had a hesitation on opening the throttle, particularly from standstill at the lights.
Eventually sucked it up and started paying more for straight 95 Ron petrol (super unleaded) and the hesitation disappeared completely.
Worth it for the extra $1-$2 a week.

 

[deputy5211]

I'd be trying a non-ethanol blend for a while and see if it helps. I ran 95 Ron with 10% ethanol for a few years, and had a hesitation on opening the throttle, particularly from standstill at the lights.
Eventually sucked it up and started paying more for straight 95 Ron petrol (super unleaded) and the hesitation disappeared completely.
Worth it for the extra $1-$2 a week.

95 is the highest I have seen here in the states, save the occasional SuperFuels stand offering 100 unleaded.

I have yet to see anywhere offering on-ethanol blended fuel, at least between Texas and California. I remember up somewhere between Cairns and Tully...

 

[Centaurious]

Replace your plug wires. I just did mine and the poor running and bad mileage went away. I now get 48.5 mpg US.

Pretty poor construction on the factory wires. Makes for easy fabrication, but the wire end to the connectors is a bad design. Not a solid connection and prone to corrosion. Might need to cut one open and show everyone.

Best of luck.

 

[cealbrecht]

Thanks for the suggestions. I had thought about the O2 sensor, but I wasn't sure how that would only effect my cornering.... I will need to take her out again and verify that I don't have an acceleration issue at low RPM when riding vertical. Maybe the stutters occur after a drop in RPM's followed by a sudden acceleration?? I will let you know if I have any other specific symptoms.

What would you expect the bike to do, if the internal fuel line were cracked inside the tank? Wouldn't there be more problems with less gas in the tank? I haven't noticed any difference in the symptoms as the tank becomes depleted of fuel.

 

[Cochinosucio]

What would you expect the bike to do, if the internal fuel line were cracked inside the tank? Wouldn't there be more problems with less gas in the tank? I haven't noticed any difference in the symptoms as the tank becomes depleted of fuel.

It will deteriorate quickly, eventually not running at all.
Does it stutter on left and right curves?
Is it worse when cold? Warm? Or both?
Does it idle smoothly at all times?
Does it stutter all the way up to 6-7K rpms? ( stutters thru the entire rpm band)

 

[jrh2020]

I would vote for the O2. My experience is more with cars, but fuel filters typically exhibit as loss of power at sustained high power (high fuel flow rates).

Jim H.

 

[cealbrecht]

It will deteriorate quickly, eventually not running at all.
Does it stutter on left and right curves?
Is it worse when cold? Warm? Or both?
Does it idle smoothly at all times?
Does it stutter all the way up to 6-7K rpms? ( stutters thru the entire rpm band)

It stutters on both left and right curves.
I think it's the same cold and warm.
The bike sounds like it might have a small sputter about once every 2 seconds when idling, but it's not a big movement on the tach.
I will need to experiment with the RPM's but right now my answer would be no....I don't remember a problem when I'm cruising on the highway or above 3k rpms.

 

[Cochinosucio]

Run seafoam through it while waiting for your new 02 sensor to arrive.... and always buy the best gas you can.

 

[Voyager]

I'd be trying a non-ethanol blend for a while and see if it helps. I ran 95 Ron with 10% ethanol for a few years, and had a hesitation on opening the throttle, particularly from standstill at the lights.
Eventually sucked it up and started paying more for straight 95 Ron petrol (super unleaded) and the hesitation disappeared completely.
Worth it for the extra $1-$2 a week.

I have the sam problem with my LT, hesitation when starting out, particularly once the bike is warmed up. When cold it isn't noticeable, but one warm it hesitates and sags below 2,000 RPM. I believe the issue is ethanol related also, but can't find any real gas around here to buy anymore.

 

[cealbrecht]

OK, new data...

It stutters on acceleration from low RPM to about 3.2k. Once it's revving above 3500rpm, there is very little noticible effect except that she gets only 39 mpg on the highway. I don't notice any stutter when cold. Could this be the O2 sensor? Is there any way to clean an O2 sensor or should I replace it?

How should the bike run if the O2 sensor was removed? Shouldn't it run rich all the time and have no stutter at all in the lower RPM's?

 

[Cochinosucio]

Chad,
Don't run without the 02 sensor. Mileage drop and poor running are signs of a bad sensor. You will damage it if you try to clean it. Don't cut corners, fuel mixture issues can be devistating to your motor.

 

[gunny]

Symptoms as described would get me to thinking about that O2 sensor.

Run a good dose of Sea Foam through it, a whole can to a half tank of gas.

 

[cealbrecht]

Latest update:

Spent $130 for new O2 sensor and special tools to remove the old one. Went for a test ride with the new O2 sensor. I could tell right away that something was different. The bike was smoother and better between the gears and a 1 hour ride displayed a highway MPG of 44. This is a 4-5 MPG improvement.

However, my low RPM stutter is still there. I don't like the stutter. It's a dangerous nuisance. I'm afraid I'm going to stall out one of these times when pulling into traffic. My idle is rough when the engine warms up and the bike kicks and bucks when accelerating out of a corner or when accelerating after braking for a turning car, etc.

 

[Cochinosucio]

Latest update:

Spent $130 for new O2 sensor and special tools to remove the old one. Went for a test ride with the new O2 sensor. I could tell right away that something was different. The bike was smoother and better between the gears and a 1 hour ride displayed a highway MPG of 44. This is a 4-5 MPG improvement.

However, my low RPM stutter is still there. I don't like the stutter. It's a dangerous nuisance. I'm afraid I'm going to stall out one of these times when pulling into traffic. My idle is rough when the engine warms up and the bike kicks and bucks when accelerating out of a corner or when accelerating after braking for a turning car, etc.

I've got it! I never asked if this was done. No doubt the 02 sensor was PART of the problem, but not the whole problem.
Take the topcase off, remove the black cover, and remove the YELLOW CAT CODE PLUG. The hesitation is caused by the motronic alternate fuel map. That will fix it. It takes 15 minutes. If you don't have the YELLOW CAT CODE PLUG, then look up "Cut the brown wire" under search.
That should do it!

 

[cealbrecht]

No, it's not the brown wire. I cut that a few years ago. I think I've got a vacuum leak or a bad fuel injector. (it's what I would have guessed, if I hadn't already cut it)

Can the fuel injectors be pulled without removing the tank? I'm getting the feeling that the tank's coming off next weekend....