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Engine troubles


expvet

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I have a 2006 VFR with 8,800 miles on it. Today while riding home stopped at a light the engine began to run rough and the idle dropped below 1000 rpm. It stayed on but was low on power. I rode it home and could rev up to 4000 rpm but it felt like it was misfiring. There was no backfire. When I got home and put the bike on the side stand the idle suddenly smoothed out and I could rev it without issues but once I got on and straightened it out off the stand in a few seconds the bad idle from earlier began. This repeats consistently. I noticed that from one exhaust muffler (I have Leo Vince) the exhaust is cooler than the other but cannot say if this is different than usual since I have never compared the two before. Last year near the end of the summer the bike suddenly would not turn over. This was remedied with new plugs but it has only been about 1,000 miles or less that I have put on these plugs.  Any ideas?

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Check your wires going into each coil. I've had both a bent electrode on a sparkplug possibly from a mouse getting in the cylinder and I've also had loose pins in the waterproof connectors of the coil. You'll know that's the issue if you move the wire harness around each coil it will lose a cylinder. Wouldn't hurt to add an extra ground to the ECU like in my earlier thread. That made it run much smoother.

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@ klrtovfr

Good idea, will check wires and connectors this weekend.

 

 

@ VARIABLE9 

Not good idea, sold stock to VFRWorld member in Toronto.

 

If anyone has other suggestions, please chime in.

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From a cold start monitor the exhaust temperature of number 3 cylinder, compare it with cylinders 1 or 2. If the bike is running rough and number 3 exhaust is not heating up like the others, you may have a ruptured Fuel Pressure Regulator diaphram, this causes excess fuel to be dumped into cylinders 3 & 4 via the vac hoses.

 

I also once had some terrible idling issues caused by either bad fuel or excessive condensation in the tank. Tank drain and fresh fuel sorted that out.

 

Check all your vaccumm lines for cracks/leakage, especially the lines to the MAP sensor, in doing that you'll be able to also have a good look at your air filter.

Good luck, keep us posted.

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I’ve got Staintune’s on mine and from standing at the rear of the bike the left hand exhaust is always warmer and has a higher velocity. I am not worried about is as from the bottom collector the exhaust gases come through one pipe and then split into the two exhaust cans, same as your Leo Vince system. If you stick your hand over the left hand exhaust can everything comes out of the right. 

 

WRT your idle and engine issues, have you got a volt meter installed? It could be your stator, rectifier/regulator or battery playing up especially if your fan was running.

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My guess is the side stand switch.  Replace it it's a cheap part that is very easy to change out.  When this circuit is being interrupted even slightly it can cause rough running, hesitation, etc.  Been there done that with my VFR800.  

 

 

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Mine was going bad but the bike still ran just not well.  It felt like something was interrupting the engine power.  Pressure on the switch or movement on the switch (like shifting) would immediately get rid of the issue until it happens again.  Trust me, I went through the whole process of replacing every normal suspect and it all came down to that damn sidestand switch.

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16 hours ago, Rogue_Biker said:

Mine was going bad but the bike still ran just not well.  It felt like something was interrupting the engine power.  Pressure on the switch or movement on the switch (like shifting) would immediately get rid of the issue until it happens again.  Trust me, I went through the whole process of replacing every normal suspect and it all came down to that damn sidestand switch.

I have heard too many times issues with those sensors. Ridiculous how often they are finicky and leave riders stranded. 

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I very much appreciate the suggestions. Last weekend I removed the airbox to check the vacuum hoses, everything looked fine. This weekend I will drain and replace the gas, check the fuel pressure regulator as well as the injectors and wires leading to it. I will also pull the plugs and look at their condition, but they were installed new way less than 1,000 miles ago. Will report my findings when done.

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  • 2 months later...
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It has been a while but this Northeast summer was one of the rainiest bad riding ones I can remember. As stated earlier the misfiring was something that would mysteriously disappear when I would put the bike on the sidestand and resume when upright. I was going to disengage the sidestand and test the fuel regulator but while doing some on and off the sidestand observation I began to notice that what was affecting the the good idle/misfiring was really when my weight  (185 lbs.) was on and off the seat. When I started to look at it from that angle I observed that my Power Commander, which is in a small slot right behind the rear brake fluid reservoir, was directly under a tab on the underside of my Sargent seat. I noticed a slight depression on the Commander's case right where the tab sat. I relocated the PC in the slot so the tab totally clears it and that seems to have resolved the issue. It seems as if the slow building of the depression eventually must have resulted in pressure on a circuit board component that either cut or interfered with a signal that messed with the mix. The bike even runs a bit smoother in the lower revs. It possibly may have been showing some gradual performance degradation signs as the depression was building that were too subtle to notice at first but eventually led to the misfiring issue. It has been flawless the last three days of commuting ,so I think this may have solved the problem. What a nightmare, had I not found this and went through the sidestand and pressure regulator checks without results it would have gone to a shop, which may or may not have found the real cause of the problem but definitely would have been a couple of hundred bucks. Thanks to all for pointing me through the process of elimination, it helped isolate the cause. Now to enjoy some fall riding before the weather turns into winter storage time.

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Well, what a good find Expvet. Amazing to think that a bit of pressure on the right spot of the PC box would create your issue, glad you've solved the problem, such a simple fix. Thanks for the follow up, a good issue to remember.

Enjoy your ride.

Cheers.:beer::wheel:

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