GreginDenver

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Also, if I remember correctly the "glowing FI light" can be caused if somebody put LED bulbs in the instrument panel lighting, including the FI light position. You can put LEDs into every instrument panel position except for the FI light position. The FI light position has to remain old-school incandescent.

I think you might have a problem with your measurements (your multimeter testing results). If I remember correctly you're supposed to disconnect the stator from the motorcycle's electrical system for testing. If you test with the stator still connected to the R/R (and as a result, connected to the entire bike's electrical system) you'll get strange/unreliable results. I remember reading explicit directions in one of my motorcycle service manuals to insure the stator is disconnected from the system for testing. That's what Urbanengineer is referring to: However, the picture in your last post makes it look like somebody "hard-wired" the stator into the bike's electrical system, so you can't quickly disconnect the stator. Is that correct?

Beware, Regulator/Rectifiers are sneaky things. A failing R/R will sometimes give a good (enough) reading when the unit is cool, but after you've ridden for a bit and the R/R heats up its performance can change a lot (and usually for the worse).

Stop, Wait, Hold on for a moment... there might be a really easy, simple explanation for this situation. And it's an easy thing to check (just by looking at the front brake lever on the right handlebar) When people mess with the front brake lever on the VFR800 (like when they take it off to service/rebuild the front brake master cylinder) they sometimes put the plunger in backwards. I'm talking about the golden-colored piece of metal that transmits your hand-force between the "cup" on the inside of the front brake lever and the front brake master cylinder piston. When this piece is installed backwards it sets up a situation where the pressure from braking the bike cannot properly bleed off when you release the brake lever, so the pressure builds up (bit by bit) and locks the brake just as you described. I'm referring to part number 13 in this picture. If it's properly assembled it will look like this: You will be able to see the tapered portion of the part. If it is installed backwards you won't see any taper on the part.

How old is the battery? I mean really? How old is that battery? How much sitting has that battery done? Have you addressed the 5th Gen weak battery charging wiring? Trouble in this area is inevitable with the 5th Gen VFR800 (gonna happen eventually, along with death and taxes). Some 5th Gens go longer before having the issues, others have it at relatively low miles, but it's coming. Installing a "VFRness" is a very good idea. You'd be amazed at the problems a bad battery can cause. And one of your comments, saying that things got worse during your ride, is a common indicator of a battery issue. The 5th Gen's PGM-FI ECM is a pretty advanced unit for its time, but one thing it does not do is compensate ignition coil "dwell time" for low battery (electrical system voltage). The ECM does compensate (correct) the fuel injector control pulse width (injection time) for low battery voltage. If your battery is going bad and dragging down the bike's electrical system while you're riding it will negatively affect the performance of the spark plugs because with lower system voltage the coils will not reach full "saturation" during the ECM-commanded dwell time. You may be experiencing intermittent weak spark plug performance (or a situation that just gets worse the longer/farther you ride it). Bottom line analysis (disclaimer - opinions are like assholes, everybody's got one): Problems that obviously/noticeably vary during operation, during the course of a ride, are often battery/electrical problems.

I'm in San Diego all the time (I'm a Southwest Airlines pilot).

Basic thought: First, you're not getting any FI light codes. This means the PGM-FI ECM has proper connections with all of the sensors. It also indicates that the sensor inputs the ECM is receiving are within the generally-expected range of operation for each parameter. This is good news but it doesn't rule out a situation where one or more of the input elements of the FI system might be operating in a strange way and is producing inaccurate readings (Throttle Position Sensor, Coolant Temp sensor, Intake Air Temp sensor, Barometric Pressure sensor, Intake Manifold Negative Pressure sensor, Engine Revolution Speed sensor, Camshaft Pulse sensor). If you read the VFR800 Service Manual Chapter 21 "Technical Features" Page 21-11, you'll learn that the VFR800's PGM-FI runs (fuels) the engine in 2 different modes depending on how far the rider twists the grip to open the throttle plates (moving the Throttle Position sensor). At lower throttle openings the controlling parameter in the fueling computations is the Intake Manifold Negative Pressure sensor. At wider throttle openings the controlling parameter is the Throttle Position sensor. Your description of your VFR's behavior sounds like the ECM is having trouble determining proper fueling while the engine is in the part of the operating range where the Intake Manifold Negative Pressure sensor is used as the controlling parameter. You seem to indicate that the bike pulls powerfully (as it should) when the RPMs are high and you're at wider throttle opening (on the throttle hard), so this suggests that the engine is fueling properly when the ECM is using the Throttle Position sensor as the controlling parameter.

I think there's an important operating principle that Urbanengineer is pointing out here: The fact that the Flapper is electrically controlled but vacuum operated. So when it is electronically "activated" it still needs intake vacuum (from a port on the solenoid valve that connects into the airbox). Which is to say there's a difference between "enabled" vs. "activated".

My guess would be that Honda has upgraded the technology and abilities of the ECU making the PGM-FI much more capable and responsive. Possibly the development efforts that went into creating the Fuel Injection system for the VFR1200 (and possibly other motorcycles in the Honda stable) may have been applied to the 2017 VFR. This may have rendered the flapper valve's effect unnecessary. However, the fact (possibility?) that the 2017 VFR800 has undergone further development to the point it doesn't need a flapper valve in the airbox doesn't retroactively nullify the flapper valve's positive effect on the lower RPM operating characteristics of earlier VFR800's. It would be rather anti-evolutionary, flat-earth thinking to suggest this as a reason to say the older generations of the VFR800 didn't need it.

Maybe you shouldn't use words like "restrict" and "reduce" when talking about this situation. Doing this misdirects/confuses thinking on the issue (and encourages the "more is always better" crowd to do things like disabling the flapper valve). Most of your thought-process and writing on the issue (in this thread) sounds perfectly logical. Your feelings about the engine's air intake requirements seem right on to me. It's a VTEC engine, right? So, if I understand the 2006 VFR800 correctly, up to a certain RPM the engine is only breathing in through a single intake valve per cylinder. So the flapper stays closed during this phase of operation which probably increases the velocity of the air passing into and through the airbox and onward through the throttle body, and maybe as a result this improves engine response/smoothness/efficiency to throttle changes while at lower RPMs. Most people don't read Chapter 21 of the VFR800 Service Manual, but this is the chapter titled "Technical Features" (at least it's Chapter 21 in the 5th Gen VFR800). In this chapter Honda reveals details about the PGM-FI system's operating principles. If you read this chapter carefully you'll learn that the VFR800's PGM-FI system uses 2 completely different fueling strategies depending on the engine RPMs. At lower RPMs the PGM-FI fuels the engine via a "Speed Density" strategy which uses the intake manifold negative pressure that is provided by the MAP sensor located in the airbox as the controlling input. At higher RPMs the PGM-FI fuels the engine via "Alpha-N" which uses the Throttle Position Sensor located on the throttle body assembly as the controlling input. So the flapper valve stays closed during the phase of engine operation that the PGM-FI is using the MAP sensor as the controlling item in the fueling strategy. Makes sense to me. When the flapper valve is closed the airbox probably produces a much better (i.e. more accurate and more responsive) intake air pressure signal.

And... Also under the general heading of "air flow" is the need to clean the accumulated grease and coating of road grime off of the radiators. Anything coating the radiators will interfere with (reducing) their ability to dump heat into the atmosphere.

So I was wrong about the operational polarity of the Honda Tachometer, everything else I stated about how the instrument operates was correct. Learning is a messy, piecemeal process. You don't always get a neat-and-complete package of knowledge right away. Sometimes all you get it a hint or basic starting point. Now it appears the "fellow down on his luck" took what I wrote and did exactly the right thing: he traced the Service Manual wiring diagram in an effort to confirm or disprove what I said. And through his efforts he now knows the truth of how his Honda's Tachometer is driven (intermittent 12 volt DC, constant ground rather than the more common constant 12 volt with intermittent ground). It would seem that we were making progress towards a solution or diagnosis... And then you showed up. Your comment was meant to accomplish what?

How's the view up there on the moral high-ground?

Well, leave it to Honda to do it the opposite of what is the norm. So, same operational principle I outlined earlier, only with ground as the constant and an RPM-based voltage input (probably 12 volt, but could be less, maybe 5 volt, with Honda who knows?). I've just looked up the Tachometer in my 5th Generation VFR Service Manual and the inspection procedure for the gauge shows that my guess is correct about the way Honda decided to run it. To inspect/test the VFR's Tachometer you hook up a Multimeter (set to DC volts) to a peak voltage adaptor and put the red (positive) probe on the Yellow/Green wire at the 10P (blue) connector block. Then start and run the engine at idle. If you get 10.5 volts or better, but the Tach doesn't work, replace the Tach if you get under 10.5 volts, replace the ECM if you get 0 volts, check the wiring continuity of the Yellow/Green wire to the ECM