Misfire at steady cruise

[Fred W]

I've always wondered if 10% ethanol in the fuel isn't the cause. The bike was engineered and tested in Japan where there may not be ethanol in the fuel.

It would be easy enough to test that theory. Did you happen to notice that there are several stations in Vermont that sell "No Ethanol Premium" gas? I put some in my Vstrom back in May and couldn't really tell any difference except for the added mileage. Might be worth running a tank to see if it does anything for the lumpy idle.

 

[3dogs]

You say that you can "hear" the missfire but can you feel it during a ride? My 05 has a slight burbble sound from the stock exhaust but it does not actually missfire when riding. Also, lean surge and a lean misfire are 2 different things. The lean surge usually happens at a specific rpm can be eliminated by a PCIII (or PCV) and a slightly richer fuel trim at the rpm and throttle position where the surge occurs. A lean missfire will feel like one, or more cylinders not firing consistently and the engine will loose power.

You mentioned that you added propane at idle and the engine smoothed out. The idle mixture is probably set too lean at the factoryand the propane just moved the AFR richer. You can run a hose from the propane bottle (in a tank bag) to the air box and go for a ride. At the point that a lean surge (or misifre takes place open the propane valve and see if the surge goes away. (you have to be careful doing this as you will be steering with one hand (or no hands)--maybe have a passenger operate the propane???

 

[Smerkal]

So far the bike is still running amazingly. I ordered the auto tune module now too, we'll see what that does. Fuel mileage is only down slightly, maybe 1-2 MPG, but well worth it and could easily be attributed to my riding habits

.

 

[learnin4life]

There must be some kind of "FJR karma" because I've been fretting with my 09 for a few months trying to determine the source of intermittent loss of power when cruising at constant speeds. Having read this thread I'm convinced its the lean mix at certain points on the ecu map (or however you want to characterize the problem :dribble: ). After checking the air filter, changing the plugs, performing a TBS, and adjusting idle speed, I was concerned I may have to take the bike to the local dealer. I have to say I don't have much confidence in those guys, so having a forum tested option to taking that giant risk is a great outcome. I'll save a bit and order a PCV later this year.

This forum is the bomb!! :yahoo:

 

[Blue Crab]

So, apparently you are one of the people that cannot feel it. It's there, believe me.

I have seen more FJRs than I can count and every one of them has the standard stumble at idle.

I could go on all day. I'd like someone to post a video of an FJR that doesn't have the lean stumble, and then tell us what the heck you did to get rid of it.

I installed a set of PAIR blocking plates and installed a PCIII. Neither fixed my "lean stumble". I also experience deceleration popping (even with the PAIR blocking plates). I ended up selling my PCIII and just live with it now.

Also, what you might *think* is a misfire at steady cruise could actually be wind noise / buffeting messing with your brain. Try this... run down the highway at 60 MPH with your head up in the air-stream over the windshield. You'll probably notice an unevenness or "misfire" sound. Next, raise your windshield to maximum then lean forward and put your helmet into the quiet zone where you hear absolutely no wind noise. I'll bet you money that your engine will sound like a purring kitten with no misfire sounds.

Steve

 

[Fred W]

The lean stumble is not something that you hear at cruise speeds. But you can feel it as a sort of hunting or surging feeling at steady throttle.

Also, if you couldn't fix it with a PCIII then it wasn't lean stumble. Lean stumble can definitely be cured with a PCIII if you add enough fuel.

Of course you do need to have a good fuel map loaded, or get one made. And you do have to disconnect the O2 sensor or all bets are off.

 

[Blue Crab]

The lean stumble is not something that you hear at cruise speeds. But you can feel it as a sort of hunting or surging feeling at steady throttle.

Also, if you couldn't fix it with a PCIII then it wasn't lean stumble. Lean stumble can definitely be cured with a PCIII if you add enough fuel.

Of course you do need to have a good fuel map loaded, or get one made. And you do have to disconnect the O2 sensor or all bets are off.

I ran my PCIII with the Smoothness map. And, yes, I disconnected my O2 sensor. Anyway, I still get heavy popping (when warm) during deceleration with PAIR blocking plates installed. And I do get a slight hunting at highways speeds (happened with and without the PCIII). So at this point IDK. Love the bike and just ignore the little annoyances.

 

[Fred W]

I have a 1st gen, and when I loaded the "Wally smoothness" map it did not resolve my surging either.

I ended up getting another map from a forum member with an '05 that had previously paid to have his bike mapped on a dyno.

That one was considerably richer in all of the appropriate fuel cell areas of the map, as could be seen in the DynoTune PCIII utility. My fuel mileage isn't the greatest, and I've been accused of having a somewhat rich smelling exhaust at times. But I do get 40-42 mpg (which is OK for the lower geared 1st gens) and the bike runs really well, so I have never gone the next step to get myself a custom map. I figure that a lot depends on the guy running the dyno, so a new map may or may not be better than what I have now. And while richer may be objectionable to some followers, it is a much safer place to be for the engine, as it will run cooler.

Sorry we didn't get to talk before you ditched the PCIII, you may have been able to use it to meet your goals. But if you can deal with the surging, as many seem quite willing to do, the benefit of better fuel mileage is real and may be worth the minor aggravation.