GEN2 stumble during takeoff

[kt4vq]

Here is a picture of the old plugs in order. 2 and 3 are running very rich.

 

[Mihalis fjr]

Just to update. I replaced plugs, checked plug caps, went for test ride.

Still has stumbles at 1.5-2k and just after 2k it runs perfectly.

I failed to provide one other symptom, for the last 20k miles at warm or cold idle the bike would (miss a lick) once every minute or so. It was not consistent just once in a while. Since plug change that is not happening. Just the stumble on take off. No load throttle twist there is no stumble, just under load does it stumble.

My 03abs had the same symptom.After changed the TPS for free due to the recall,the engine runs smooth from idle to red zone..But firstly i would try a throttlebody and injector cleaning before to buy a new TPS sensor ..

 

[John Scottorn]

TPS Throttle Possition Sensor

Apologies for coming in late to this... and not yet read others advices.

My TPS was replaced when I had my Gen1 and I suspect all is not right with my Gen2 in the throttle area.
Hunting occurs e.g. when trying to keep a steady pace in 2nd gear at 20mph. It has also cut-out several times in (2 thousand miles of use), on take off and left me in embarrassing positions.

She was synced about a thousand miles ago.

I'm fearing the cause may be similar ???

 

[RossKean]

Here is a picture of the old plugs in order. 2 and 3 are running very rich.

View attachment 4650View attachment 4651

No guarantee, but the fact that #1 and #4 are good but #2 and #3 aren't, may point to ignition coils and/or wires/connections. There are two coils and #1 and #4 are on one of them. #2 and #3 are on the other... Measurement of coil and/or wire resistance may not be a good representation with what happens with HIGH voltage and when coils/wires are hot.

 

[Diablo1]

Since it’s running rich, change your air filter.

 

[Lou D]

I had a 2006 that did the same thing. I installed a power commander and enrichened the bottom end quite a bit and it ran as good as my new one. Done.

 

[Rocnsanman]

Brand new battery one week ago.

I had an 07 while living in Colorado and had a similar issue. I attributed the issue to a well documented altitude glitch and learned to ride through it. Got the Ivan Flash and the altitude/ stumble issues went away.

 

[ALFJR]

As stated above, check the battery voltage with the engine running, preferably something over 3 or 4K RPM. Voltage should be something greater than about 13.5 volts. I had a similar problem on another bike, and it was related to the charging system.

I know the battery is new, however, you could give it a good overnight charge, then measure battery voltage with the key off, engine stopped. Then ride the FJR until the problem shows up, then measure battery voltage with key off engine off, and look for a significant voltage drop. compared to the reading right after the overnioght charge.

I had a Suzuki with symptoms similar to yours and it turned out to be a charging system issue. I know the FJR is not a Suzuki, and the the FJR is much newer than the bike I had, but given similar symptoms and the above simple tests have no parts cost, I thought to present the above.

I am hopeful you will get this resolved soon! Cheers!

 

[RossKean]

Since it’s running rich, change your air filter.

I would certainly have a look at it for the 10 minutes it takes, but I doubt this is the issue. It would affect all cylinders similarly and it would have to be AWFUL in the first place to have an observable effect on running. Different in the days of carbed bikes that couldn't compensate fuelling for intake air flow resistance. The FJR filter flows LOTS of air. When I look at mine, I see most of the "dirt" generally at one end which suggest to me that most of the air is mostly passing in that area. If it was uniformly dirty, I would assume that there was significant resistance to flow.

I had a 2006 that did the same thing. I installed a power commander and enrichened the bottom end quite a bit and it ran as good as my new one. Done.

Except that this appears to be a new behavior. I think I might try enriching the CO via the Barbarian Jumper mod first. I would be concerned that changing the fuelling via CO settings OR PC might mask an unrelated problem.

I had an 07 while living in Colorado and had a similar issue. I attributed the issue to a well documented altitude glitch and learned to ride through it. Got the Ivan Flash and the altitude/ stumble issues went away.

Again, a new behavior and the fact that it appears to affect two cylinders more than the others makes me think the root cause is different. I would want to get to the bottom of that first.

No question that the '07 has issues with lean fuelling at low throttle openings and will be helped by enriching lower RPM ranges with a PC, replacing the ECU with one from a 2009-12 or getting it "flashed" by Ivan.

I put 295,000 km on an '07 - the first 60,000 with a PC. Took the PC off for the sake of fuel economy and got used to the snatchy throttle. Never experienced what I would call a "stumble".

 

[Diablo1]

So, how does the FJR compensate for a dirty air filter? If there isn’t a mass air flow sensor, it can’t. Those plugs all look too rich to me. What voltage is measured on the TPS at idle? Any measurement showing it’s not working properly? Old bike with low mileage may need injectors removed and cleaned.

 

[RossKean]

O2 sensor feedback controlling the A/F ratio... intake air pressure sensor... I am not entirely certain exactly how these systems work together but it is far more than just chance. We know that the system adequately compensates for high altitudes (less air) - insufficient frequency of pressure measurements for altitude changes was the reason for the altitude sickness recall to replace ECUs for early GenII.

Resistance to air flow is very low until the filter gets really dirty.

 

[Diablo1]

O2 sensor feedback controlling the A/F ratio... intake air pressure sensor... I am not entirely certain exactly how these systems work together but it is far more than just chance. We know that the system adequately compensates for high altitudes (less air) - insufficient frequency of pressure measurements for altitude changes was the reason for the altitude sickness recall to replace ECUs for early GenII.

Resistance to air flow is very low until the filter gets really dirty.

My mistake, I forgot the FJR is closed loop injection. Every bike I own is open loop.

 

[thefix]

You need to check the Air Flow/vacuum sensor bolted to the back of the throttle bodies. It sits towards the left and has a single hose on it. Remove the sensor (2 small bolts 10mm heads I think). Disconnect hose carefully, use a safe cleaner (alcohol , WD40, mineral spirits , or maybe lacquer thinner due to it's fast evaporation) on both the NIPPLE and Hose end. The nip and possibly hose is often clogged a bit with these symptoms. Do not spray things into the nip unless its an electrical cleaner which evaporates in seconds, some folks use brake cleaner which is strong. I do not know the exact composition of the sensor. That's why I hesitate on spraying things in. Carefully clean out , something brown/black should be obvious, and reassemble. May need to replace the short hose section. This is a new issue. Ran great before. Don't mask the symptoms by "reinventing the wheel".

 

[RossKean]

You need to check the Air Flow/vacuum sensor bolted to the back of the throttle bodies. It sits towards the left and has a single hose on it. Remove the sensor (2 small bolts 10mm heads I think). Disconnect hose carefully, use a safe cleaner (alcohol , WD40, mineral spirits , or maybe lacquer thinner due to it's fast evaporation) on both the NIPPLE and Hose end. The nip and possibly hose is often clogged a bit with these symptoms. Do not spray things into the nip unless its an electrical cleaner which evaporates in seconds, some folks use brake cleaner which is strong. I do not know the exact composition of the sensor. That's why I hesitate on spraying things in. Carefully clean out , something brown/black should be obvious, and reassemble. May need to replace the short hose section. This is a new issue. Ran great before. Don't mask the symptoms by "reinventing the wheel".

The inlet air pressure sensor (MAP) normally generates a Fault Code #14, if it is a problem. Easy enough to remove the hoses and clean out any accumulated crap. I would not spray ANYTHING inside the pressure sensor itself! I had a Fault Code #14 issue and the cleanup solved it. The blockage was entirely within an inch of the sensor in the hose coming off it. Symptoms don't sound like what the OP is describing, but it is possible.

https://www.fjrforum.com/threads/fault-code-14-gen-ii-solved.170314/

 

[BkerChuck]

If you decide you do need a TPS, I have a brand new one still in packaging I bought for my '07 but never installed. That bike is since gone and the part can't be returned. Let me know if interested. I'd cut a deal on selling it.

 

[ALFJR]

Did this ever get resolved? If so, what was the fix? Inquiring minds want to know.

 

[kt4vq]

No, the issue is not resolved. Sorry, I had some family health issues/death that I had to attend to before continuing the repair efforts.



I created this little jig for cleaning the injectors. The cheap fuel pump I got for the jig only provides 6 lbs of pressure so I am not sure the injectors are delivering the true pattern. In the videos, the injectors are making a two-stream pattern. I expected to see a fan pattern.



The service manual states 47 ibs of pressure so I am trying to find an “inexpensive” fuel pump. All I am finding are very expensive. Any ideas for a fuel pump that will deliver at least 45 lbs of pressure on the cheap?
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