Another weird issue on a 2002 vfr800

VFR 800 VTEC "Cutting Out" whilst rolling.. [Archive] - Honda VFR Club

This is EXACTLY my problem. Except I set my idle speed higher, and it stays there, then slowly falls back.


http://vfrworld.com/forums/mechanic...ps-too-low-intermittenly-when-engine-hot.html

This as well, seems to happen when the bike is hot, and I ride in traffic the whole way home. Could it really just be the bad fueling of the early 6th gens?

 

i think the manual says to adjust idle when the engine is hot, probably after the wax melts in the fast idle unit.

If you adjust before that happens then the idle speed will drop when the FIWU does melt and closes the fast idle port. If you screw in the throttle stop screw too far to get the idle up then the TPS gets out of the idle voltage range and confuses the PFI computer even more.

The voltmeter has replaced the screwdriver as the mechanics first tool, but not by choice...

 

That's the thing I raised it when it was hot, right after getting home yesterday. Then on the ride in this morning it was obviously too high because after a few minutes it was idling at like 2k and actually got hung at 2500 with the clutch disengaged. I stopped and got the tool kit out and lowered the screw back to normal, and it was fine the rest of the ride. I wasn't in heavy traffic so the bike didn't get that hot on the way TO work. On the way home it got hot and I was in stop and go traffic, the idle then dropped to 1k RPM and it cut out on me once as I was rolling to a stop.

 

Go look at this current thread--having wax unit issues also. Appears to be very sensitive to adjustment. If it is out then you probably can't use the throttle stop screw to do any good until the wax unit is okay.

http://vfrworld.com/forums/mechanics-garage/41493-2007-vfr-800-vtec-cold-start-not-working.html

 

Thanks. I may have to check that out. Mine never even jumps up to 2k when I start it, it sits at 13-1500 rpm, it's also about 75 degrees in the morning here now though.

 

Well the Honda dealer told me to run premium fuel and seafoam through about 3-4 tanks, to fix the idle problem. He said the previous owner didn't ride it enough (2002 with 7500 miles) and probably didn't ride it very hard. He blamed injectors

What are your thoughts on that:?

 

Well the Honda dealer told me to run premium fuel and seafoam through about 3-4 tanks, to fix the idle problem. He said the previous owner didn't ride it enough (2002 with 7500 miles) and probably didn't ride it very hard. He blamed injectors

What are your thoughts on that:?

 

Haha! You, sir, have been dismissed. Clogged injectors would cause a consistently rough idle and poor rideability.

Look, if you really want to diagnose this, you're going to have to tear into the bike a bit. Start by inspecting and cleaning the kill switches, etc. It does sound like the wax unit needs replacing, however that doesn't entirely explain the engine cutting out spontaneously. You also need to measure the charging voltage ASAP to make sure the charging system is working correctly--if it's not, that could explain the low idle and the spontaneous engine stalling.

Sorry, wish Seafoam would be the right answer.

 

Did your bike have the recall done? What about having a VFRness installed?

 

The idle used to fluctuate all over on my 2007. I was constantly adjusting it and it really got annoying. Engine ran great, started great, but the idle just would not stay consistent at all.

 

Yeah, it's currently in the shop getting the wiring harness and brake recall completed. I asked them to check the charging system too.


I think the bike knocks out because the idle drops so low when it gets hot. It only drops that low when the temp is around 220. Then if I let off the gas quickly while coasting to a stop the engine knocks off when the idle drops to barely 1000 rpm really quickly.

 

Did you ask the dealer if your bike has been updated ??????? That just may take care of all this. Shit, my bike had 400 miles put on it in 5 years when I got it with 1800 miles, and ran like a top---- I think he was yankin ya chain there buddy boy

 

TheBeeDeeGee are you willing to poke around your bike a bit? I would suggest you try Let me throw a few things out there, and you decide if you are up for it.

Idle is controlled by 4 air bypass valves which are part of the throttle body assembly. These valves are actuated together by the wax element, which gets it's heat from the cooling system. Also, an idle adjustment screw is present on the air bypass valves actuator arm, and allows for adjustment of idle. Throttle body is under the air box, which, of course, is under the fuel tank. Idle can also "somewhat/very little" be regulated by the computer and the amount of fuel, but this is NOT the primary idle adjustment, as it causes rich or lean conditions. Primary idle adjustment is through air bypass valve assembly in the throttle body.

Anyhow, back to the point here, I think you should try to eliminate parts of the idle control one by one and see where condition improves or at least stops to be erratic. In order to do this, you will need to gain access to the throttle body assembly, which means lifting/pivoting the gas tank, and taking off the air box. After you get to the throttle body, on the right side of it(right side of the bike), you will see a "comb style bracket" with 4 screws on the black plastic washers. This is your idle actuator. In the same area, you will see a screw for idle adjustment. The other side of the actuator is connected via a small link to the wax element. Wax element also has 2 small coolant hoses leading to it.

After all this is located, I would go in the following sequence:
1) Is there anything visually out of place, like loose screws (idle adj. screw), loose bypass valve screws, loose wax element connection, etc. Be through on this step.
2) If everything checks out, disconnect wax element from the actuator (not from the coolant lines), and test out the bike. You do not even need to put air box back in actually, just start it up and see if idle is erratic. Open throttle a few times and snap it close to see if idle stays adjusted.
3) If this does not solve the issue (if wax element is good), I would check the throttle body synchronization. This is the procedure where you make sure air flow through all 4 TBs is the same at idle, and it will require a vacuum gauge (or a mockup of it . If you search the forums you should be able to find the instructions on how to sync throttle bodies.
4) If throttle bodies are in sync and pull the same vacuum, next thing to check is fuel delivery and pressure on deceleration. Clogged fuel filter can cause bad fuel delivery as well. Get a good fuel pressure test kit (auto stores have them for rent) and test out if there is a fuel pressure drop when you go from open throttle to closed.
5) Now, if all this checks out ..... I am out of ideas

If all this may sound like it is something that should be left to a mechanic, it isn't. Removing the air box takes roughly 8-10 screws all together, and a few vacuum lines. I think anyone a bit handy with a few tools should be able to get to the throttle body fairly easily. I am also assuming you have a service manual, procedures are explained in detail in it. If not, let me know, and I can probably send you a copy.

 

Yeah seems that way. The bike runs great otherwise, this is an annoyance more than anything. It always cranks back up, it's just irritating that the idle drops so low when the engine temp rises.

I have the service manual on my PC, I feel confident that I could look into this stuff. Thanks for the info.

 

I have about the same problem here, but my idle doesn't seems to be low when the bike is hot

When I'm braking (without releasing the clutch), if I give a quick turn of the gas handle (I don't know the right english expression ) to reach about 4-5k (RPM) the bike dies instantly. I see the RMP raising and decrease directly to 0 (never stop to idle.

It's really wierd, I'm not able to do that when the bike isn't running. I really need to be braking and giving a little shot of gaz...

Do you thing it's the same problem ?

 

No, I don't think this is the same issue. My bike will knock off at idle once it gets up around 220 degrees Farenheight. The idle speed at that temp drops from 1500 to 1000 rpm and will knock off from time to time.

 

Also.....is anyone else's idle speed adjuster hard to turn?

 

Hm, adjuster screw is tensioned by a spring, if I am not mistaken, so it will be somewhat harder to turn than free spinning screw. On my bike it feels like screw that has some blue threadlocker on it, or some gasket maker on it. I can definitely feel the tension, but I can still turn adjuster screw with three fingers and a screwdriver.
It could be that your adjuster screw is messed up or fully in or out .... Did you get a chance to look at it directly?

 

I've seen this on the SV and the interceptor before. Thread locker red, maybe?

One of the center stand bolts (swing arm side) is left hand thread. Ask me how I know... If you break it, I have an extra new one.

 

Double check their work. I discovered on mine that the old harness got left in place and they just zip tied the new one over the old one! Naturally, some connectors were strained.... Asshattery at its finest.