| Author | Message | ||
     Nik |
As the bike is approaching 37K I'm getting progressively worse and worse gas mileage. I just filled up and netted ~36mpg. This is particularly annoying since I have the smallest tank of any of the XB line and am now getting <100 miles/tank. A year ago I was getting 45-52 mpg and now its 35-42mpg regardless of riding style or freeway/city. It has a stumbling idle that needs some throttle not to die sometimes and off idle throttle response is rather delayed. TPS reset didn't do anything, resetting the AFV helped a little but only for a short time. I've searched here and come up with the following suspects: 1) O2 sensor, no codes but they do age and wear out 2) Head temp sensor, could explain the crappy idle when warming up 3) IAT, because... why not just suspect all the sensors that give input to the ecm? 4) intake and injector gaskets, air-leak making the ecm compensate with more fuel? Anyone have any other leads? | ||
| Boltrider |
spark plugs | ||
| Nik |
Brand new NGKs. | ||
| Boltrider |
You have a good list to start from. Also maybe a weak battery? Tough to say because it could be so many things. | ||
| Nik |
current ecmspy screencap. Bike has cooled down for 3 hours. Ambient temp reads 26 degrees C at nearby airport.  | ||
| Boltrider |
Your battery voltage looks a bit low. It should be somewhere between 12.8 and 13.2 with engine off. Try charging it and see what happens. | ||
| Iamarchangel |
When was the last time you checked the air filter, air being an unmentioned part of the trinity (gas, air, spark at the right time)? IAT is more for the warm-up part but the problem happens even after it's warm. So rule that out for now. It could be bad but you would notice sudden bogging when riding. Head temp would send a code and flash the engine light. I'd guess O2 but I'm not as good at new school as I'd like to be. How is it off idle? At 3500rpm? At 5000? How long is your typical run? | ||
| Nik |
Just held the throttle constant at 10% with the engine in closed loop. EGO voltage stayed near zero and EGO correction kept shooting up, driving up the revs ~500rpm and exiting CL, then they'd drop back down, and it would cycle about once every two seconds. So I'm thinking O2. (Message edited by nik on May 07, 2009) | ||
| Nik |
My typical commute is 20-30 minutes, and I always warm it up ~5 minutes. | ||
| Id073897 |
RPM 0 tells me engine is stopped, so all fuel related output isn't usefull at all. Batt. voltage with stopped engine is of no import. AFV is 1-2 steps down, nothing to worry about. TPS looks okay. ETS and IAT are somehow the same, seems okay also. Go for a ride, run a log. | ||
| Nik |
here's a log that's pretty representative of my daily riding. http://members.cox.net/hightensionwire/20090507_15 58.log | ||
| Id073897 |
All sensors look fine, meaningfull data, AFV ~100, so there seems to be no problem with the EFI. Find a workshop that has as 4-gas tester and check HC, CO and CO2. Rule of thumb: HC less than 500 and CO%+CO2% = 14-16 is fine. If HC above 1000 or CO or CO2 gives weird readings, check if an inlet or exhaust valve is leaking, thus leading to a decrease in mileage. | ||
| 1_mike |
Another thing I do at each oil change is run a can/bottle of fuel injector cleaner thru my system...no matter what bike or car engine. I use the Lucas F.I. cleaner, but others work well also. Like the name implys...it helps keep the "injectors", the ports, the valves, the combustion chambers....clean. The Lucas stuff also has an oil in it for a little help in the injector and valve stem, seat lubrication. All of this goes a long way to help keep the intake system clean and working correctly. My R1 has almost 88,000 miles on it with very little drop in gas or oil mileage. I've got two other "worn out" bikes with over 100,000 miles with the help of the Lucas cleaner...no fuel system related problems. Just a thought. Mike | ||
| Id073897 |
I don't think it's a problem with the fuel system. No sign of starvation or over-fueling. | ||
| Nik |
I'm not entirely convinced that its not in the fuel system, though I haven't counted out other things. I turned off the O2 sensor and reset the AFV at 100 so I could find any leaks without the FI chasing itself. I've only done a couple short rides but it seems to be running much better without O2 feedback. | ||
| 1_mike |
Id - Other than an vacuum leak...where else would bad mileage, stumbling and a tendency to die come from...? A locked front brake..or rear brake...maybe? That's (the intake) the first place I'd...look..! Mike | ||
| Id073897 |
Allmost everything that decreases engine efficiency. If not a leaking valve, the ignition perhaps. This I would check next, probably with the help of an oscilloscope. A locked brake or similar will easily be noticed when pushing the bike. |
