VFR VTEC 2008 - Throttle issue! (another one)

[dazza139]

I've had my VTEC 2008 for 2 months. 2nd owner. It's done 2000 km's and I'm loving it. I know a lot has been written about surging and snatchy throttle and I wonder if that's the same as what I'm experiencing. At lowish revs 2000-4000 rpms and with a constant throttle position the bike starts to surge and lag. My usual response is to change gear or change throttle and the problem goes away. Other than that the throttle is a little snatchy at low revs and low speed but I'm getting used to that. Does this sound like the typical problem with this bike or something different? I'm thinking of taking it back to the shop to get it looked at. What should I ask them to check?

[CandyRedRC46]

yep this is what to expect from your bike in stock form. this is why o2 eliminators and power commanders exist...

i know how you feel. coming from a 15 year old carborated bike onto a 11 thousand dollar machine my expectations were high. i was disappointed to say the least.

that's why i went to radio shack and picked up a pack of 330 ohm 1/4 watt resistors.
unplug your o2 sensors and plug in the resistors. it runs beautifully now. it is very straight forward and easily done there are many treads on this already.

PS who ever said that this has no point with out a power commander or 98-99 headers was mistaken. i have neither YET, and my bike feels buttery smooth now. the throttle no longer feels like an on off switch :)

[Comicus]

That's exactly how my 04 was but since i did the o2 eliminator and the power commander it's a totally different bike. Soooo smooth now!

[John451]

I've had my VTEC 2008 for 2 months.... At lowish revs 2000-4000 rpms and with a constant throttle position the bike starts to surge and lag.

Remember the V4 800 has a 12k Redline and doesn't like being below 4k especially cruising in the top 3 gears so use 4k as your minimum.

[VifferDude]

My bike ('08) Wouldn't run to well below 5000rpm for the first 10000klm because the engine was still tight. It'll pull away from 3000rpm now. But as John 451 said, this is a high reving bike. Go for a lower gear. The Viffer isn't a 2 wheeled tractor with a lumpy V twin like the Harleys

[vfrchick]

Yup... same thing on my 2007. I got a PC a while ago, and just putting that on helped "some". Finally this past Monday I did the O2 eliminators and actually had it dynotuned so have a custom map. Sooooooooooooo unbelievably smooth now, I can't believe it's the same bike. Do it, it's worth it!

[Got_Wings?]

yep this is what to expect from your bike in stock form. this is why o2 eliminators and power commanders exist...

i know how you feel. coming from a 15 year old carborated bike onto a 11 thousand dollar machine my expectations were high. i was disappointed to say the least.

that's why i went to radio shack and picked up a pack of 330 ohm 1/4 watt resistors.
unplug your o2 sensors and plug in the resistors. it runs beautifully now. it is very straight forward and easily done there are many treads on this already.

PS who ever said that this has no point with out a power commander or 98-99 headers was mistaken. i have neither YET, and my bike feels buttery smooth now. the throttle no longer feels like an on off switch :)

SOO interesting to log on and see this...I just came back from a quick ride on my newly aquired stock 03 VFR800A and the SAME exact issue is driving me nuts!

So, we've got the cheap, quick fix in the resistors....and we have the 02 eliminators + PC (w/possible dyno tuning). Hmmmm.....is the cheap n quick fix too good to be true? I'm willing to try if there are no harmful side effects. I'll be putting on a Remus exhaust this weekend so all my spare cash is now gone (read: PC is out for a while if that's the best solution)

CandyRed?

[dazza139]

Can I have the idiot's guide to finding the O2 sensor plugs? I'm definitely prepared to do this but I'm not a motorcycle mechanic

[HondaTech]

well the O2 sensors are really the only things with wires attached sticking out of the exhaust so that ought to narrow it down...personally I think the engineers know more about how that bike should run for the best combination of power, economy and emissions than I do so I'll be leaving mine alone and stick to using it as it was intended- want to go faster? shift down and use the engines operating range instead of asking an engine designed to make HP from 6k and up to do it at 3k. If you want it to pull like a train down low, buy a Bimmer with a boxer motor.

[dazza139]

well the O2 sensors are really the only things with wires attached sticking out of the exhaust so that ought to narrow it down...personally I think the engineers know more about how that bike should run for the best combination of power, economy and emissions than I do so I'll be leaving mine alone and stick to using it as it was intended- want to go faster? shift down and use the engines operating range instead of asking an engine designed to make HP from 6k and up to do it at 3k. If you want it to pull like a train down low, buy a Bimmer with a boxer motor.

Thanks. Yes I have taken on board your comments about revs and I probably have been letting the bike rev too low. Do you think that this is not a problem at higher revs. The issue for me seems to be constant throttle which causes the problem. I will have to see if its noticeable higer up in the rev range.

[crustyrider]

bro, when you kick it in, at 6500 your gonna need air breaks to stop you from shooting off the pier at the other end of the island............

[Comicus]

Can I have the idiot's guide to finding the O2 sensor plugs? I'm definitely prepared to do this but I'm not a motorcycle mechanic

I don't run the bike below 4k but the o2 eliminator plus power commander smooths the bike through out the power curve. It goes from running like a honda to running like a finely tuned honda. It's an on going debate here but I think the PCIII is worth the money.

As for the o2 sensors...you have to remove the left faring and about mid way down you'll see a plastic cover protecting 3 wire connectors. two of the connectors are the o2 sensors just follow the wires back to your exhaust(not very far about 5-8 inches). And I didn't know this until I was doing the o2 eliminator mod but there are 2 o2 sensors.

[CandyRedRC46]

As far as Honda knowing what they're doing in engineering this motor... Yeah they did know what they were doing when they originally designed this motor. Early VFR's did not have o2 sensors. o2 sensors were an after thought. Vtec was an after thought as well. These are things that the original VFR800 motor was not designed to have. Honda prides itself in being one of the cleanest manufactures in the world. These two things Honda did were done to meet ever tightening CARB emissions. I appreciate that Honda does this, I just don't like it on MY bike...

Any ways about the long run I'm hoping that these little 99 cent resistors will last, but the theory is that they're exactly the same this that's inside the 20 dollar Dyno Jet o2 eliminators... Time will tell. Hopefully I never get a FI warning light, but then again it would only be as simple as replacing them. At 5 for 99 cents you could do this 50 times and it would run you the same as Dyno Jet's two O2 Eliminators.

[Got_Wings?]

Yet another pertinent question....will the bike pass emissions with the following mods:

1) The resistors
2) The 02 eliminators
3) The 02 eliminators and the PC

(I'm in AZ, for reference)

[indyvfr]

+1 on the PCIII and O2 sensor eliminators. I ride an '07 and have 15,000 miles on it. It's been a great bike, but the throttle always seemed twitchy down low and on/off throttle. I installed the PCIII and O2 sensor eliminators and the bike is unbelievable smooth. It's runs the way I wanted it to from the beginning. I am running a K&N filter with stock exhaust, with the Dynojet "stock exhaust" map. It has noticeably more throttle response and overall has more punch to it. I would also say it's well worth the money IMO.

[CandyRedRC46]

Yet another pertinent question....will the bike pass emissions with the following mods:

1) The resistors
2) The 02 eliminators
3) The 02 eliminators and the PC

(I'm in AZ, for reference)

As long as you still have the catalytic convert in, I'm thinking emissions will not be a problem. especially with a good map. I "THINK" passing emissions on this bike would only be a problem WITH OUT a cat. Also in case you misunderstood, resistors and o2 eliminators are the same thing. My apologies if you already knew this.

[HondaTech]

As far as Honda knowing what they're doing in engineering this motor... Yeah they did know what they were doing when they originally designed this motor. Early VFR's did not have o2 sensors. o2 sensors were an after thought. Vtec was an after thought as well. These are things that the original VFR800 motor was not designed to have.

Early ones were not designed with fuel injection so there wasn't any need for oxygen sensors- that's why they don't have them. I don't buy that VTEC was an afterthought either- it's been in the cars since around 1989 and is a great way of basically building a motor with 2 camshafts, 1 for better torque down low and 1 for better HP up high. Yamaha is after the same types of results with the variable length intake runners. No the original motor wasn't designed with these things because they either hadn't been invented yet or weren't cost practical to put into that motor. What percentage of bikes 10 years ago were fuel injected? not many. Does that mean any engine that has evolved into a fuel injected motor that began as one designed around a carburetor is inferior because it wasn't originally designed as one for FI? Look, if people want to mod their bikes I really don't care. If people don't like FI and think the carb motors are superior, fine- If you don't want VTEC fine. Personally I like technology, but more importantly I like things to work as they should, reliably, and I think Honda spends a lot of money to engineer product to perform a specific way. If you like your bike more after you mod it, cool for you- it's not for me. I just can't buy into new technology being applied to a basic engine design to improve it's performance as "an afterthought"

[Y2Kviffer]

Yup... same thing on my 2007. I got a PC a while ago, and just putting that on helped "some". Finally this past Monday I did the O2 eliminators and actually had it dynotuned so have a custom map. Sooooooooooooo unbelievably smooth now, I can't believe it's the same bike. Do it, it's worth it!

Did you get a dyno print out you can scan and post?

[CandyRedRC46]

Do the 98-99's have fuel injection? I'm pretty sure that they do not have o2 sensors or a cat. We are talking about the original VFR"800" motor aren't we? The motor that is based on the RC45... Not the VFR"750".

[300shooter]

Don't forget to mod the PAIR valve.

[CandyRedRC46]

yeah i heard the pair valve removal is a necessity for accurate air fuel ratio readings. Definitely needs to be done before dynoing. But, I think with the o2's deleted, disabling the pair valve isn't going to do anything drivability wise. As there are not any sensors to pick up that extra oxygen in the exhaust.

[John451]

Do the 98-99's have fuel injection? I'm pretty sure that they do not have o2 sensors or a cat.... The motor that is based on the RC45...

Right on all counts, the Gen 5 Mk1 is catless and has no O2 sensors and was also based on the WSB RC45 engine which also had fuel injection.

What is interesting is going from a '03 build Gen 6 to the '99 Gen 5 in '05 I have found the Gen 5 throttle is much smoother and even though I still run above 4k from choice. Also unlike my previous Gen 6 the Gen 5 has no problems or stumbling cruising around from 3k mind that may also partly be do to change to a VFR trained mechanic who syncs my SV's every service.

Like others say know Gen 6 owners who have dialed out their throttle issues with PC3 O2 sensors removed and a custom map.

[rufrydrsc2]

that's why i went to radio shack and picked up a pack of 330 ohm 1/4 watt resistors.
PS who ever said that this has no point with out a power commander or 98-99 headers was mistaken. i have neither YET, and my bike feels buttery smooth now. the throttle no longer feels like an on off switch :)

I just did it this morning and it's amazing what a difference it makes. Making U turns is so easy now that I don't have to feather the throttle just to keep the bike from bucking. Man, I wish I'dve had it like this when I took my license test.

[carlgustav]

FWIW, I did only the PAIR valve 'mod' to my '07 and that alone smoothed out the throttle response a bit, and the VTEC xsition considerably ...

[bluespecv03]

Is there an advantage to using resistors to eliminate the o2 sensors, while not having a PCiii?

[bluespecv03]

Well I decided to do the mod this morning anyway, and wow, its so smooth now!

[ewryly]

I rarely run my bike, an 07, under 4000, and I find it very smooth. It took me a while to get use to keeping the rpms after I made the switch from my cruiser to the vfr, but now it is second nature. That's not to say that pc mods wouldn't make it even smoother, but I would get in the habit of keeping it closer to 5000 at the low end and see how it behaves.

[bluespecv03]

I usually keep it above 4k, but the 99cent resistors have definetly made a difference. Its like the bike finally has what its been missing.

[CandyRedRC46]

Well I decided to do the mod this morning anyway, and wow, its so smooth now!

you keep track of your milage right? it will be interesting to see how its affected with the o2s eliminated. extra fuel injected at steady throttle vs. being able to run the bike at lower rpms.

i have seen that the harley guys do this to most of their bikes as a cure for overheating, bad fueling, etc. but they complain of bad gas milage afterwards. i guess getting 30ish mpg sucks when your no faster than your average fart can civic lol.

[bluespecv03]

Yeah I keep track of my mileage. Ill keep you posted on if there is a drop or not.