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Very poor fuel mileage after valve adjustment

swojo95

swojo95

Member
Member
Just had the valve adjustment done and my fuel mileage has tanked. 30-33mpg taking it easy on the backroads, 24-28mpg blasting down the highway, all unloaded, empty bags and I even lost 30lbs over the winter. I only run top tier premium in the bike, and the gas is fresh. The air filter has approximately 3500 miles on it and I run the tire pressures at 41/41. Bike seems to run fine, nothing jumps out as wrong, except this. Just looking for some insight on what to check that would cause such a drastic change in mpg? I took the plastics off for inspection and I did find that the inlet air pressure sensor rubber mount was not installed in the bracket. I am assuming these sensors are sensitive to any impact, and thus why they are rubber mounted the way they are? One theory, I am speculating on, is that the sensor, not attached, "bounced around" on top of the engine, due to rough roads around here, and damaged the sensor in such a way that the reading is off enough to cause ECU add more fueling? There are no codes or faults generated. The National is coming up quick and I stressing over how to fix this? Any input would be appreciated.
 
So, a little more information, the person who did the valve adjustment, also adjusted the TPS sensor, which I am learning is something he should not have done. The service manual gives a procedure to test the sensor input and output voltages, but specifically calls out in bold, that it should not be adjusted. It may also be that the TPS sensor is going bad, since he adjusted it due to voltage outputs lower than specification. He also noted that the battery charge was low at the time (11.7V) of the voltage test, and I am wondering if that could have played a part? I am thinking now that the ECU is receiving a signal that the throttle is open farther than it actually is, and commanding more fuel than it actually should. I am going to try to set the TPS back to the original location and see if that doesn't get me back some fuel economy, and if it does, then I believe the issue will be identified, and I will then have to determine the best approach to actually setting it, if that is even possible? Of course, if the TPS is bad, that is a whole another can of worms.
 
Steve in sunny Fla said:
Input voltage 4.75 to 5.25 v Output idle .6 to .62 v. output wot 3.9 to 4.1 v
Click to expand...
Steve, you are the man. Thanks for the call earlier, it was great hearing from you and I believe you were spot on about the TPS. When I got off the call with you, off came the right side plastics and I adjusted the TPS as close as I could to the original setting. Lucky enough, these bikes get pretty dirty, and with all the dust trapped under the plastics, there was a pretty good outline of where the screw used to be, and with a set of jewelers glasses, I was able to adjust it pretty darn close to where it originally was. Upon starting the bike up cold, the fast idle was maybe 100-200rpm over the 1100rpm idle, which was very promising versus the 1800-2100rpm that it was. Amazingly, I only had to rotate the sensor ~1mm and it made a huge difference. First off, as soon as I hit the road, the bike was very noticeably smoother, the buzz I was getting in the handle bars and foot pegs was gone........ gone. As I travelled down the back roads at 62-65mph, my instant readout was showing me that I was averaging ~ 45mpg, a heck of a lot better than 32mpg. A sigh of relief. I was only able to get about 30 miles on the bike and I did not get a chance to get some real world fuel mileage, doing the math, but that will come soon. I did get out to the super slab for a few miles, and set the cruise at 78 and the display indicated 38-40mpg, which is way better than the 24-28mpg I had yesterday at those speeds. Of course I need to get some longer, real riding in to see the full affects. I will update when I get a chance to put on some more miles. It's amazing what effect that 1mm adjustment had, did I mention smooth. Now, I have no way to tell exactly where the sensor was set originally, I know I am very close, but it seems a very minute rotation can have a big impact?

So, to everyone out there, if you take your bike somewhere for a valve adjustment, I would recommend letting them know you do not want them messing with the TPS adjustment.
 
Ok, ill be THAT guy....why did he? Why would he? Did he provide you with an explanation on either? Did he think it had something to do with syncing the throttle body?
 
swojo95 said:
Steve, you are the man. Thanks for the call earlier, it was great hearing from you and I believe you were spot on about the TPS. When I got off the call with you, off came the right side plastics and I adjusted the TPS as close as I could to the original setting. Lucky enough, these bikes get pretty dirty, and with all the dust trapped under the plastics, there was a pretty good outline of where the screw used to be, and with a set of jewelers glasses, I was able to adjust it pretty darn close to where it originally was. Upon starting the bike up cold, the fast idle was maybe 100-200rpm over the 1100rpm idle, which was very promising versus the 1800-2100rpm that it was. Amazingly, I only had to rotate the sensor ~1mm and it made a huge difference. First off, as soon as I hit the road, the bike was very noticeably smoother, the buzz I was getting in the handle bars and foot pegs was gone........ gone. As I travelled down the back roads at 62-65mph, my instant readout was showing me that I was averaging ~ 45mpg, a heck of a lot better than 32mpg. A sigh of relief. I was only able to get about 30 miles on the bike and I did not get a chance to get some real world fuel mileage, doing the math, but that will come soon. I did get out to the super slab for a few miles, and set the cruise at 78 and the display indicated 38-40mpg, which is way better than the 24-28mpg I had yesterday at those speeds. Of course I need to get some longer, real riding in to see the full affects. I will update when I get a chance to put on some more miles. It's amazing what effect that 1mm adjustment had, did I mention smooth. Now, I have no way to tell exactly where the sensor was set originally, I know I am very close, but it seems a very minute rotation can have a big impact?

So, to everyone out there, if you take your bike somewhere for a valve adjustment, I would recommend letting them know you do not want them messing with the TPS adjustment.
Click to expand...
You're going to have to get Mark to readjust his also. If you feel you want to solve the problem, direct the tech to me for an explanation.

Steve
 
Yeah, I already shared the information with Mark, he also has the high cold idle, but his mpg did not drop off as much as mine. He also said he had a bit more buzzing in the lower rpms than before the service, so we will be adjusting his sensor back to the original setting also. Thanks again.
 
Konehead34 said:
Ok, ill be THAT guy....why did he? Why would he? Did he provide you with an explanation on either? Did he think it had something to do with syncing the throttle body?
Click to expand...
I questioned him about it after I read what the service manual stated for the TPS adjustment, which was basically don't touch it. He didn't really offer up a reasoning as to why. I think he adjusted it due to the output voltages testing below the Kawasaki specs, but he also stated the battery only had 11.7V and the manual states that the battery should be fully charged for the test? I am not sure if that was an issue though, as the input voltage was within spec? For everything else, he does do a thorough job and documents everything with numerous pictures, at a reasonable price. He has done valve adjustments on numerous Concours 14s, so I am a little surprised that no one else has had a similar issue? My bike may have been more of an outlier, where the negative effects were more noticeable?
 
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Murph said:
Most people dont have a meter that has the tolerance to be accurate in that volt range..they aint cheap.
Click to expand...

Murph said:
Most people dont have a meter that has the tolerance to be accurate in that volt range..they aint cheap
Click to expand...
Interesting, here is a picture of my bike and the meter he used. I do not believe this is an expensive meter? This is a pic he took of the input voltage to the TPS.
Multimeter.jpg
 
I've never heard of em' ,Flukes pretty much rule with the pros. The tolerances are normally in the paperwork but depending on where it was manufactured Im not sure Id trust that. The guys at the mill would compare meters as a field test to make sure their readings were good.
 
Murph said:
I've never heard of em' ,Flukes pretty much rule with the pros. The tolerances are normally in the paperwork but depending on where it was manufactured Im not sure Id trust that. The guys at the mill would compare meters as a field test to make sure their readings were good.
Click to expand...
When my son was in school to be an electrician, fluke was all that was recommended by the instructors.
 
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