Kirdro Posted April 27, 2012 Share Posted April 27, 2012 So I filled up today, and am sitting at 22.5mpg. I've never gotten fantastic gas mileage out of my vfr, but this was the worst it's ever been! Most of my riding has been around town, and I've averaged around 28mpg and highways in the low 30's (31-33). So, list of mods.... De-Californication Pair/Snorkel removal O2 sensor disabled (resistors) Cat-back Scorpion exhaust PCIII (cozy's) Running temp ranges: 180-210 Fuel: Premium 91 Any suggestions? Link to comment Share on other sites More sharing options...
BillyZ Posted April 27, 2012 Share Posted April 27, 2012 Ditch the premium and go with the 87. Doesnt make sense to me, but I have heard it works. Link to comment Share on other sites More sharing options...
Viffer88 Posted April 27, 2012 Share Posted April 27, 2012 Keeping your rpm below the VTEC range greatly improves mpg. Link to comment Share on other sites More sharing options...
Member Contributer tbzep Posted April 27, 2012 Member Contributer Share Posted April 27, 2012 Ditch the premium and go with the 87. Doesnt make sense to me, but I have heard it works. Premium has less energy in a given amount than regular, according to some sources, but I believe it has roughly the same stored energy. The true purpose of higher octane fuel is to help prevent detonation. If the bike doesn't detonate on regular, there's no need for premium. The only reason high octane is related to performance is because it allows for higher compression ratios without detonation. Link to comment Share on other sites More sharing options...
spud786 Posted April 27, 2012 Share Posted April 27, 2012 Your temperatures look good, so Id say the map is too rich for your bike. Id expect to give up a couple mpg's with a power commander, but the map is going to make a Huge difference too. Link to comment Share on other sites More sharing options...
Member Contributer Duc2V4 Posted April 27, 2012 Member Contributer Share Posted April 27, 2012 When I first put in my PCV I noticed a drop in MPG but never that significant amount of difference. I also heard that running 87 Octane helps but I have yet to try it. Maybe the next fill up I'll give it a go. Unless it starts detonating, the worse that can happen is that I save money, at least 10 cents/gallon at most stations. Link to comment Share on other sites More sharing options...
Monk Posted April 27, 2012 Share Posted April 27, 2012 The common practice back in the day when there were an abundance of octane choices at the pump, the way it was done was to put in the high-test and see what happens(Knock or no knock), if no knock then go down a grade till it did knock, then go up one grade, as there's no advantage to running any higher than that............ The best time to do this was in the hotest part of the summer..... Or just not learn anything from history. Link to comment Share on other sites More sharing options...
spud786 Posted April 27, 2012 Share Posted April 27, 2012 The vfr seems to do okay on 87 octane, but Ive run all 3 grades and it really doesnt make a difference on milege. Link to comment Share on other sites More sharing options...
Member Contributer NorthernVFRDave Posted April 28, 2012 Member Contributer Share Posted April 28, 2012 Run a few more tanks before you worry too much. Could just have been a stale tank of fuel at your last fill up. And your wasting you cash on 91oc fuel. 2 reasons. 1. 6th gen doesn't call for it, like everyone has said. 2. Tank is only 22liters a multi-grade gas pump can hold between 10-12liters of fuel in all of the pipe work. So unless your getting gas behind someone that used 91oc your getting half a tank of whatever the guy before you bought. Link to comment Share on other sites More sharing options...
Member Contributer Cogswell Posted April 28, 2012 Member Contributer Share Posted April 28, 2012 Do the plugs and air filter check out as good? Also, if the gas mileage issue started with the mods, double check all vacuum hoses, etc are all connected properly. Link to comment Share on other sites More sharing options...
Monk Posted April 28, 2012 Share Posted April 28, 2012 Buy the proper octane for your vehicle Contrary to popular belief more octane doesn't make your engine perform better nor is the gasoline any cleaner than lower octane ratings. Octane is a burn retardant, that means that it slows down the rate of combustion (burning) for gasoline. Octane ratings higher than those required by your engine actually decrease performance, albeit very slightly and probably imperceptively at that, so buying higher octane ratings than needed just wastes money. I am not reccomending violating your owner's manual requirements, if your owners manual says to use mid grade or high test then by all means do it, don't jeopordize your warranty to save a few cents per gallon, but if you're adding high test because you think it is better gas and your manual doesn't suggest or require it, then you should revisit this logic. posted by bates on January 04, 2009 this tip works for 85% of voting Fuelly members. Link to comment Share on other sites More sharing options...
Member Contributer 2thdr Posted April 28, 2012 Member Contributer Share Posted April 28, 2012 What ambient air temps are you running in? If in cooler temps and you have sticky t-stat issues (like sticking open) and your coolant temps are not getting up past 180 degrees F, the EFI will send extra fuel until the bike "warms up". My bike always gets worse mpg in cooler temps... Link to comment Share on other sites More sharing options...
dallasb Posted April 28, 2012 Share Posted April 28, 2012 Read what Monk said here again, at least 3 times, there is such a misconception out there. This is truth. Buy the proper octane for your vehicle Contrary to popular belief more octane doesn't make your engine perform better nor is the gasoline any cleaner than lower octane ratings. Octane is a burn retardant, that means that it slows down the rate of combustion (burning) for gasoline. Octane ratings higher than those required by your engine actually decrease performance, albeit very slightly and probably imperceptively at that, so buying higher octane ratings than needed just wastes money. I am not reccomending violating your owner's manual requirements, if your owners manual says to use mid grade or high test then by all means do it, don't jeopordize your warranty to save a few cents per gallon, but if you're adding high test because you think it is better gas and your manual doesn't suggest or require it, then you should revisit this logic. posted by bates on January 04, 2009 this tip works for 85% of voting Fuelly members. Link to comment Share on other sites More sharing options...
spud786 Posted April 28, 2012 Share Posted April 28, 2012 Read what Monk said here again, at least 3 times, there is such a misconception out there. This is truth. Buy the proper octane for your vehicle Contrary to popular belief more octane doesn't make your engine perform better nor is the gasoline any cleaner than lower octane ratings. Octane is a burn retardant, that means that it slows down the rate of combustion (burning) for gasoline. Octane ratings higher than those required by your engine actually decrease performance, albeit very slightly and probably imperceptively at that, so buying higher octane ratings than needed just wastes money. I am not reccomending violating your owner's manual requirements, if your owners manual says to use mid grade or high test then by all means do it, don't jeopordize your warranty to save a few cents per gallon, but if you're adding high test because you think it is better gas and your manual doesn't suggest or require it, then you should revisit this logic. posted by bates on January 04, 2009 this tip works for 85% of voting Fuelly members. The vfr as long as you dont develope alot of carbon raising the compression it does okay on regular. Some of the High test fuels actually have higher level of detergents, even if you cant benefit from the higher octane. Exxon used to be one of those fuels, their Premium had much higher levels of detergent, But this guys problem has nothing to do with the grade of fuel he's running. Even though its been repeated 10 times. Link to comment Share on other sites More sharing options...
Guest Posted April 28, 2012 Share Posted April 28, 2012 Make sure the Air Filter doesn't look like this!! Link to comment Share on other sites More sharing options...
Member Contributer pres589 Posted April 28, 2012 Member Contributer Share Posted April 28, 2012 Remove the Power Commander and see what happens. Link to comment Share on other sites More sharing options...
Kirdro Posted May 4, 2012 Author Share Posted May 4, 2012 Thanks for the suggestions! I definitely don't think it's the high octane though, since I've ran high octane the entire time I've had it. I was more concerned about the recent drastic drop rather than the overall low mileage. Definitely don't have a rat's nest in my air cleaner :) and I swapped out spark plugs a month and a half ago, so likely not them either. I'll double check my map, just in case something screwed up with the power commander and my map switched (it's been about 6 months since I installed cozy's map). Link to comment Share on other sites More sharing options...
Veefer800Canuck Posted May 4, 2012 Share Posted May 4, 2012 Leaking fuel pressure regulator. Fuel leaks through the diaphragm inside the FPR and into the vacuum signal hose and into the throttle bodies. Link to comment Share on other sites More sharing options...
Member Contributer vfrurknee Posted May 4, 2012 Member Contributer Share Posted May 4, 2012 You didn't mention the mileage on the bike. Is it high enough to require valve adjustment or starter valve sync? I have the gauges to do the starter valve sync and am only 38 miles away. Link to comment Share on other sites More sharing options...
Member Contributer CharlesW Posted May 4, 2012 Member Contributer Share Posted May 4, 2012 So I filled up today, and am sitting at 22.5mpg. I've never gotten fantastic gas mileage out of my vfr, but this was the worst it's ever been! Most of my riding has been around town, and I've averaged around 28mpg and highways in the low 30's (31-33). So, list of mods.... De-Californication Pair/Snorkel removal O2 sensor disabled (resistors) Cat-back Scorpion exhaust PCIII (cozy's) Running temp ranges: 180-210 Fuel: Premium 91 Any suggestions? Just one. Check it again. Many things can contribute to a single fill-up giving a bad mileage result. Probably the most common is operator error, either in the math or not filling the tank to the same level for each time. It's been a week, have you filled up again? Same results? Link to comment Share on other sites More sharing options...
Member Contributer YoshiHNS Posted May 4, 2012 Member Contributer Share Posted May 4, 2012 Up until I noticed it was a 6th gen, I was going to say check for spark. I'm going to suggest it anyways. That's how I managed to get 25mpg on my 96. The wires for my ignition coils came off a couple of them. Link to comment Share on other sites More sharing options...
Member Contributer Ryanme17 Posted May 4, 2012 Member Contributer Share Posted May 4, 2012 Any suggestions? Just one. Check it again. Many things can contribute to a single fill-up giving a bad mileage result. Probably the most common is operator error, either in the math or not filling the tank to the same level for each time. This seems likely to me. With only a 5 gallon sample, it's easy for your data to be off. You should average your readings over several fill-ups to be sure. If you filled it all the way to the neck one time, and didn't the next time it could be off. Or one pump was less accurate than another, it's easy to be off by 30%. And maybe you got bad gas. Maybe you're used to 100% gas and you got an ethanol blend. Link to comment Share on other sites More sharing options...
enzed_viffer Posted June 12, 2012 Share Posted June 12, 2012 Leaking fuel pressure regulator. Fuel leaks through the diaphragm inside the FPR and into the vacuum signal hose and into the throttle bodies. Are there any symptoms of this Rob, apart from poor economy? I just filled the bike up this morning, and a quick calculation says I got only 25mpg on the last tank. Admittedly, that was all commuting at often much less than 90km/h, but even so, it's lower than I expected. Admission #2 is apart from changing the oil and checking tyre pressures, I've done no maintenance on the bike this year (haven't even washed it for as long as I can remember). Next up (when/if I ever get time) is to clean or replace the air filter. Checked the plugs last night - they just look like plugs (albeit a bit weird, coz they're iridium NGKs). Link to comment Share on other sites More sharing options...
Guest Recalcitrance Posted June 12, 2012 Share Posted June 12, 2012 Happened to me once. Dropped down into the 30's mpg. Dirty fuel. After I burned through that tank, mileage went back to normal (45-50mpg). Or what they said up there. If it's a sudden drop after your last fill, it could just be something simple like a bad tank. *shrug* I'd burn through it all then fill up again and see what happens before you go digging around your innards. Also, another +1 on the "Ditch the premium." Doesn't make a difference and the VFR is made to run on regular. I ran it on Premium for a while and it actually felt worse. My $.02 Link to comment Share on other sites More sharing options...
Veefer800Canuck Posted June 12, 2012 Share Posted June 12, 2012 Ian, I've never had a bad FPR myself but you would have bad mileage, fouled plugs and rich smelling exhaust. It's real easy to lift the tank, remove the vacuum line to the FPR and fire the bike up. If its leaking, you'll know right away. Depending on how bad it is, you might have to let it run a few minutes. Link to comment Share on other sites More sharing options...
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