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Discussion Starter · #1 ·
Short summary:
About 30 minutes into a 1 hour each way ride (on a hot day) my bike started hiccupping really bad. It continued off and on for most of that ride. A new tank of gas and a bunch of short trips to/from work (on colder days) and no issue at all. A third tank of gas, another longer weekend ride, and it starts doing it again. I performed some maintenance, filled it with a fourth tank of gas, and today on the way into work, split up into very short trips to gas station/gym/work and during a colder morning - no issues. I go out at lunch time, it's hot again, and the hiccups return.

Hopefully this video is accessible.
New video by Don Carano

In the video you can see the rpms shoot up as normal on a few, while other times it stuttors on the way up. Sometimes you can see the RPMs bouncing around. On the last throttle pull you can hear that the hiccup wasn't a one time thing, it was going to continue to run like shit until I dropped the RPMs and applied throttle again.

What the hell is going on???
 

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Discussion Starter · #2 ·
Here are more detailed observations:
  1. Sometimes it would pull hard but just drop out for a split second throwing me forward, then kick in full power again throwing me backward.
  2. Other times (like the last pull on the video) it will spit and sputter for as long as I want it to... I can keep the throttle at the same spot and she acts like she has no power to spare and the RPMs bounce around.
  3. The hiccups can occur for a few seconds or up to a minute. Then the bike will run good for 1 - 10 minutes before they return.
Recent maintenance (I was hoping it was a fuel issue):
  1. New gas from new gas station.
  2. Replaced fuel pump, fuel pressure regulator, and fuel strainer.
  3. New plugs on the rear (it was easy to get to them while I had the tank off).
The bike is a 2012 with 5.5k miles. The ECU was flashed for the stock exhaust I have on her. Note: I did put a new-to-me stock black exhaust on along with the flash, so I could have screwed up the EXUP valve in the exhaust, but I can't see how that would be so intermittent. I did put on homemade air box covers on, but again, why intermittent?

My best guess is that this is some sort of ignition issue. when it's one big hiccup it feels like the ignition just completely cuts out for a split second, then snaps right back in. When it's the "bouncing RPMs" it feels like she is bouncing off the rev limiter (I'm way below that, sometimes down around 2.5-3k it will continue to 'bounce').
 

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Check wires around ignition and such, sounds like a loose connection, check all plugs and start wiggling wires around while idling, it could even be a bad ignition switch, I had a car where the ground to the ECM was loose and would do all kinds of stupid ignition stuff. never heard of these bikes stumbling like that. might have to borrow another ECM to see if there is an issue with the programming it could even be the kickstand switch.
Definitely post what you find just in case someone else goes through this, I am very curious.
 

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Discussion Starter · #5 ·
Thanks for the response. I'll dig into loose wires. Not sure how far I'll get though as it never stumbles at idle, never stalled.

I'll definitely report all findings.
 

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Does it do it at any throttle position? I'm talking about position as in rotation of the throttle. Vehicles that have a throttle position sensor, when they get worn can act that way, And that can be intermittent depending on how well the sensor is making contact. I had a truck that about drove me nuts trying to find out why it would stutter, and sometimes the transmission shifting would get erratic. It was the TPS on it that was bad.
 

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Discussion Starter · #8 · (Edited)
Excellent ideas!

My first step will be to replace the front spark plugs. I saw mention in years-old posts about how the ignition coil sticks like to come loose and have intermittent contact. BCS reiterated this as a possibility via PM. Hopefully I find the front ignition coil stick loose, but I'll replace the plugs anyway.

Interesting thought on the TPS, I'll dig into this one as a second step. If it isn't a loose connection, this one kinda makes sense to me. When it's doing the "RPMs bouncing" thing, it feels like one of the rev limiters where it retards the timing (I don't know if the rev limiter on this bike is one of those or the kind that just cuts the ignition). I'm not suggesting the rev limiter is kicking in prematurely, only that it feels like the timing suddenly becomes way off! Anyways, if the computer doesn't have the correct inputs for gear, RPM, and throttle position then it could be applying the incorrect timing map - so even I'm applying a nice even throttle maintaining speed, the computer is applying an ignition map as if I'm applying full throttle and changing the timing. Boy, the more I think about it, the more this makes sense for the "RPMs Bouncing" issue I have. And it's possible the TPS is intermittent as well so it could apply to the "Ignition cuts out for a split second" issue.

Note: I do not definitively know if the ignition cuts out for a fraction of a second or if fuel flow ceases completely for a fraction of a second. I have not eliminated fuel flow at this point, but ignition seems more likely based on what I've done to date.
 

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There is a lot going on under the hood for sure.
Timing, Fuel, STP (actuator and feedback), IAPS, GPS, TPS, CKPS, IATS, ISCV, fuel system, ignition coils, etc.
And since you have the stock exhaust on the bike, EXCV & EXCVA also have to be added into the equation as well.
Not to mention the possibly of interment electrical issues at any point on the bike.
It can be a real bear sometimes trying to find an interment issue like the one you are encountering without the use of diagnostic software.....or you may get lucky and find something obvious very quickly.

Timing maps are static, think of them as an Excel spread sheet.
RPM in the left column and Throttle Position across the top.
So your ignition timing output signal from the ECU would be whatever value is in the cell that intersects the left RPM and Top Throttle position values.

Your TPS fuel maps are set up the exact same way.
So if you are in the TPS fuel map range >10% TP timing and fuel outputs would follow each other in lock step.

You mention in your post that this is occurring at 2500 - 3000 RPM.
At that rev you probably still in the IAP fuel map range (<10% TP) and not running on the TPS fuel maps yet.
Are you also experiencing these issues at higher RPM values? Like between 4000 - 5000 RPM?

I know none of what I said above actually helps your situation at the moment, but wanted to paint a picture of what you are potentially up against in your troubleshooting endeavors.

Post up what you find as you dig into it and we will assist you as much as we can over the internet.

Are you getting a FI fault indication (red fault light on tachometer) at any time?

Where are you located?

BCS
LGB/FJB
 

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Discussion Starter · #10 ·
I'm in Massachusetts.

All of this helps... knowledge is power. :) I bought my wife a mini cooper convertible in the winter on the cheap because the top did not work. It took me a month of research and diagnostics (that damn top has 7 different computers and 22 different sensors/inputs... grrr!) but I was able to fix it. This just sucks because I always have a back-up bike... except right now my back up is a VMAX I just bought that needs the carbs cleaned, tank replaced, etc.

This failure can occur at any RPM. But there are two distinct failures that may not have the same root cause.
  1. "Ignition cuts out for a split second" - This can occur at any RPM and at any Throttle position, meaning if I'm maintaining speed I can feel a very tiny 'bump' that is barely noticable. Or it can occur under WOT where I'm holding on, the power cuts off for a split second and I fly 6" forward until the power kicks back in and I fly backwards on the seat! Again, any RPM.
  2. "RPMs bouncing" - Again, it can occur at any RPM. This is when it feels like I'm hitting a rev limiter that is severly retarding the timing. At a constant speed it feels like a stuttor/surge and sometimes I can make it keep doing it for what feels like an eternity (probably only 10 seconds) until I drop the throttle/apply throttle a few times. If I try to apply more throttle at that point it just feels worse and b-a-r-e-l-y accelerates.

Timing maps are static, think of them as an Excel spread sheet.
RPM in the left column and Throttle Position across the top.
So your ignition timing output signal from the ECU would be whatever value is in the cell that intersects the left RPM and Top Throttle position values.
So if the TPS were to tell the ECU I was applying 10% throttle, but I was actually applying 75% throttle, wouldn't the amount of fuel being delivered (for 75% throttle) not match the timing (adjusted for 10% throttle)?
 

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So if the TPS were to tell the ECU I was applying 10% throttle, but I was actually applying 75% throttle, wouldn't the amount of fuel being delivered (for 75% throttle) not match the timing (adjusted for 10% throttle)?

Lets use 15% as an example.
If the TPS was outputting a value equal to 15% TP but you were actually at 75% Throttle, then the ECU would output the intersecting timing and TPS fuel map values for 15% TP & whatever RPM you were producing at that time. Both the timing and fuel will output the same correlating cell value from their respective maps.

Now for the 10% TP kicker.....
If you are 10% or less TP (which is most times when cruising unless your doing 80 mph or better, then you have to also introduce the IAP fuel maps into play.
The IAP fuel maps do not correlate to TP, they instead use RPM & Vacuum Pressure as variables.
So while the IAP maps are still static, vacuum pressure is not steady, so IAP fuel output values will jump around quite a bit in each RPM range.

And when you are right near the 10% TP mark, you are often jumping back and forth between IAP & TPS fuel maps.

Check the easy stuff first.
Plugs, Plug caps & wires, Coils, look for chaffed or loose wires and electrical connections.

There is also a bridge connector that ties a lot of ground wires together that has been known to cause strange issues if it starts burring up.
This is located under the left side of the tank on the upper frame rail.
It will be a dead end connector with a lot of black wires with white tracers going into it.
Can't remember of the top of my head but I think its will be a yellow or orange colored connector.
These burn up now and then and I have seen them cause interment issues until they finally burn though and the bike just totally quits.
Have a quick peak at that to see if you can see any obvious defects, corrosion or burning going on with that connector.

BCS
LGB/LGB
 

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Discussion Starter · #12 ·
I assumed the throttle cable mechanically adjusted the amount of fuel going into the engine. The TPS sensed the % throttle being applied and told the ECU, and the ECU determined the timing.

If I understand right the throttle cable really just adjusts the TPS. The TPS tells the % throttle being applied to the ECU. The ECU tells the injectors how much fuel to pass AND what timing to use, both from the same table. Thus, the timing and fuel should always increase/decrease together. They shouldn't' be out-of-whack with each other even if the TPS is providing the wrong information to the ECU.

Cool. It's more 'fly by wire' than I thought.

I'll report back when I have more info. I'll drain the tank and start dissassmbly tonight.
 

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The rev limiter cuts fuel , by the way , not the ignition. Race bikes often cut ignition , but a streetbike must pass emission regulations and spewing unburned fuel would be unacceptable.
 

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I assumed the throttle cable mechanically adjusted the amount of fuel going into the engine. The TPS sensed the % throttle being applied and told the ECU, and the ECU determined the timing.

If I understand right the throttle cable really just adjusts the TPS. The TPS tells the % throttle being applied to the ECU. The ECU tells the injectors how much fuel to pass AND what timing to use, both from the same table. Thus, the timing and fuel should always increase/decrease together. They shouldn't' be out-of-whack with each other even if the TPS is providing the wrong information to the ECU.

Cool. It's more 'fly by wire' than I thought.

I'll report back when I have more info. I'll drain the tank and start dissassmbly tonight.

The throttle cables attach to the primary throttle plate actuator on the throttle body and control the movement of the primary throttle plates.
The TPS is nothing more than a potentiometer which is used measure the movement of the primary throttle plates and outputs a value to the ECU to reference the position of the primary throttle plates.

So cables move primary throttle plates, TPS measures the amount of movement and outputs %TP value to the ECU.
This value is then used as one of the variables for TPS fuel maps, timing maps & secondary throttle plate maps. The ECU is simultaneously outputting correlated values from each of these maps to the injectors, ignition coils and secondary throttle plates respectively.
RPM is the second variable used used to correlate the output values of each of these tables.

I will post some stock maps in a bit so you have a visual reference.

BCS
LGB/FJB
 

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Discussion Starter · #15 ·
Didn't get to do much last night, but here are observations:
1. Found some extra wires coming off the battery. Then found a small box under the right side cover that looks to have powered the speakers that were on the bike when I got it. I removed the box, but the only wires left were positive and negative to battery, and a blue wire going into the fuse box. I'm assuming the blue wire is only powered when the bike is on, like a car stereo it will tell the 'box' to power on/off with the bike. Very Low probability this had anything to do with my issue.
2. The battery is the wrong size. It's a size 14. Looks like stock is a 20 and some folks go with a 16 for some extra room. I could see this causing a slow start (which I don't have) but can't see any way this could contribute to my issue.
3. The terminals on the battery are odd shaped and don't match up perfectly with the leads. Thus, the contact area between leads and battery is less than desirable. Again, she cranks and starts no problem, so I can't imagine this has anything to do with my issue.

The battery is brand new. Should I just go ahead and replace it to eliminate it as a variable?

To be continued...
 

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Discussion Starter · #18 ·
Can a guy put a multimeter on the TPS and see if the resistance is straight and linear with throttle movement?
I don't know. But the bike is supposed to know if the TPS is faulty and throw a code (C14). That, and other codes, aren't available unless you get a dealer tool known as, "09930-82720: Mode select switch". My understanding from searching this forum is that it is nothing more than a jumper... some folks suggesting a paperclip could work. However, I have had EXTREMELY positive customer service interactions with a company, DB Electronics, so I ordered one from them to throw them some business. It should be here tomorrow. It also looks very easy to adjust the TPS once I get the super-duper special dealer tool.

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You can measure the change in resistance from the TPS with a multimeter, but it's hard to measure on one that just has a slight worn spot, like where you are normally holding the throttle at your normal cruise speed. If you watch the meter while someone very slowly rotates the throttle you might see the meter reading take a dip instead of showing a steady rise. But since your problem is occurring at multiple throttle positions, I doubt this is it unless the connection on the TPS itself is not secure and making intermittent contact.

Something BCS said above kind of reminded me of a problem that showed up on here a while back. As he said, your throttle rotates the primary throttle plate. But nothing happens until the ECU tells the secondary throttle plate to open. So you have the secondary throttle plate actuator, and a secondary throttle plate sensor that does the same thing as the TPS to provide feedback to the ECU on what position the secondary throttle plates are in. A bad connection at any of those could cause your problem. Now in the past there were some who removed the secondary throttle plates completely, which works as long as you don't whack the throttle wide open at low rpms, which just bogs the engine like an old 4 barrell carb with mechanical secondaries would at low rpm.

From your description, it really seems to me to be an ignition issue instead of a fuel issue, especially if it feels like the bike cuts off completely at some points. Just a gut feel. And as Slave said, I wouldn't bother with the battery as long as it starts OK. Once it's running it gets more than enough power from the alternator to run the ignition.

And while you have the tank off checking the bridge connector, look closely at the harness going to the throttle bodies. The old Power Commanders used T tap connectors that cut into the wires. It was pretty common for those wires to corrode and cause all kinds of problems. And make sure the connectors are firmly attached to the throttle bodies.

Good luck with it, I'm sure with some perseverance you'll figure it out. :)
 
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