[Guest]

Anybody know how to adjust the throttle position sensor? Is that something that we can do without "special tools"? I'm still struggling with suddenly crappy mileage. Already got new oil, plugs are clean and fairly new (only about 2K miles since they were changed), tire pressures are good. So I'm out of ideas...used to get consistent 40mpg, now it's 35 if I'm lucky. I'm not beating on her any more than I ever have, so I don't get it.

 

[Hink]

40 MPG is pretty high for this bike. 32-35 is about the normal. I wouldn't spend too much time trying to fix a "problem" that probably doesn't exist. JMO

Have you done any performance mods?

 

[rynosback]

Why do you think it is the TPS sensor? I do not think it would cause your complaint. How is your idle? Have you checked the voltage out of the TPS and swept it? It could be the gas you are using.

 

[justbman]

Didnt you get the memo about the TPS report? :joke:
(sorry, I had too)

 

[Guest]

40 MPG is pretty high for this bike. 32-35 is about the normal. I wouldn't spend too much time trying to fix a "problem" that probably doesn't exist. JMO

Have you done any performance mods?

40mpg might be unusual, but unless I've been hallucinating through the first 15,000 miles, there has been a significant change.

No mods aside from K&N air filters, but I just put those in yesterday...this has been going on for the last month since I got the bike back on the road this spring. At least 4 or 5 tanks of fresh gas at this point...no change in mileage.

 

[Guest]

Why do you think it is the TPS sensor? I do not think it would cause your complaint. How is your idle? Have you checked the voltage out of the TPS and swept it? It could be the gas you are using.

Can't the TPS make it run rich if it's not working properly?:dontknow:

I'm guessing here...I've tried buying gas at a few different places...didn't seem to change anything.

 

[rynosback]

Can't the TPS make it run rich if it's not working properly?:dontknow:

I'm guessing here...I've tried buying gas at a few different places...didn't seem to change anything.

Yes but your idle would be higher also.

TPS = Throttle Position Sensor

The more your twist the more fuel you get.

 

[Hink]

40mpg might be unusual, but unless I've been hallucinating through the first 15,000 miles, there has been a significant change.

No mods aside from K&N air filters, but I just put those in yesterday...this has been going on for the last month since I got the bike back on the road this spring. At least 4 or 5 tanks of fresh gas at this point...no change in mileage.

This really could be a higher concentration of ethonol in your gas. They're "summer blend". If I could get 35mpg, I'd be celebrating. But, my riding style is... well, lets just say, different.:evil:

 

[Guest]

Yes but your idle would be higher also.

TPS = Throttle Position Sensor

The more your twist the more fuel you get.

OK...fair enough. Idle is fine. Like I said, I was just guessing. That's why I come here...a mechanic I'm not.:bigthumbsup:

 

[Gone fishin']

I routinely get 40 to 42 mpg. It goes down a bit when I flog it too much, but I don't think 40 mpg is unreasonable. I don't think the tps will necessarily cause it to idle higher. I would look at the set valve adjustment, and also the secondary throttle valve. There is likely a restriction somewhere. There could also be a mouse nest in your airbox, Staranger things have happened. Also check all of your vacuum lines for leaks, nothing kills mileage like a vacuum leak.

 

[rynosback]

This really could be a higher concentration of ethonol in your gas. They're "summer blend". .:evil:

:agree:

 

[Guest]

I routinely get 40 to 42 mpg. It goes down a bit when I flog it too much, but I don't think 40 mpg is unreasonable. I don't think the tps will necessarily cause it to idle higher. I would look at the set valve adjustment, and also the secondary throttle valve. There is likely a restriction somewhere. There could also be a mouse nest in your airbox, Staranger things have happened. Also check all of your vacuum lines for leaks, nothing kills mileage like a vacuum leak.

Yup...that's the mileage I'm used to...no vermin in the airboxes though, that I already checked.:joke:

 

[rynosback]

I routinely get 40 to 42 mpg. It goes down a bit when I flog it too much, but I don't think 40 mpg is unreasonable. I don't think the tps will necessarily cause it to idle higher. I would look at the set valve adjustment, and also the secondary throttle valve. There is likely a restriction somewhere. There could also be a mouse nest in your airbox, Staranger things have happened. Also check all of your vacuum lines for leaks, nothing kills mileage like a vacuum leak.

I would think if the SET was not working properly, he might experience lack of power to to the back pressure build up. If it runs and idles fine, I would run a few tanks of fuel through it and see if it changes.

 

[4U2NV]

I consistantly avg 40-45 miles to the gallon. Is it possible the fuel filter is old & may have accumulated some gunk to the screen. Not enough to affect your idle but just not flowing enough?:dontknow:

 

[Guest]

I consistantly avg 40-45 miles to the gallon. Is it possible the fuel filter is old & may have accumulated some gunk to the screen. Not enough to affect your idle but just not flowing enough?:dontknow:

Restricted flow, I would think would give $chittier performance and use less gas..:dontknow:. Although I do have one on order already, so I guess I'll find out.

 

[rynosback]

I consistantly avg 40-45 miles to the gallon. Is it possible the fuel filter is old & may have accumulated some gunk to the screen. Not enough to affect your idle but just not flowing enough?:dontknow:

It would effect the performance part of it, lack of fuel not consumption.

 

[V42A9]

The fuel oxygenation occurs in the winter due to richer mixes needed to start the engine (think choke) and longer idle times to warm up (those that have remote start systems). The summer mix should give you better mileage. My suggestion is to check the coolant temp sensor output and the MAP sensors baro reading (there are two, one each for the throttle bodies). The blocked exhaust is also a consideration.

 

[Zoom]

It's easy to check your SET valve. Turn the ignition switch on and then hit the kill switch. Look under your exhaust where the SET valve is, then reach up and turn the kill switch on. The SET valve should move as the actuator cycles.

I would get a service manual if you don't have one and check all the sensors. It's not that time consuming to check the basic functions and at least you would know they are all functioning correctly and it's just something different in your riding style. I know the first few rides of the summer my fuel mileage drops a little just because I play with it a little more.

 

[L.T.T.]

Just in case someone needs info on TPS adjustment... here ya go

 

[Ozzy M109R]

I get an average of 5.5-6l/100km or 42-40 mpg (rough conversion). But it depends on air temp, traffic, mood, throttle application and other things.

Is ol'mate riding the same route every tank?

There was a mention of recently fitted K&N filters. Was this just before the fuel use change? If so I'd be looking as that being the reason for the change. If more air can get through the filter for the same throttle position, if stands to reason that the MAP sensors and O2's will alter the mixture.

I know this happened on my old mans car.

Just a thought.

Great post with the TPS adjustment page from the workshop manual!