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2007 6th generation VFR jerky throttle response


Wiggie

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I have owned a 2007 VFR800 for about a year now. It has about 8,000 miles on it, was at around 5k when I bought it. I have lusted after the VFRs since the mid 80's, and finally got one! I love this bike, my only criticisms being its weight (too much of it), and at least on mine, its jerky on-off throttle response at low speeds. What I am talking about is when taking a low speed corner, as the throttle is rolled on from completely off, there is an abrupt increase in power rather than a smooth progression. I do not believe its my technique as I am very careful to provide smooth input, and have rideen other bikes which do not do this, eg BMW S1000 RR. This has nothing to do with V-Tec as the rpms are way below the 6100-6400 level.

I have tried the following. Removed slack from throttle cable at the grip end. Did PAIR mod, flapper valve mod, snorkel removal. Checked chain slack.This all seemed to help slightly but the abruptness is still there and is rather annoying.

Can someone comment on their experience with the Power Commander and whether it solved this issue? Is there an easily available map for the PC that will take care of it?

Many thanks for any advice. And my apologies if this has already been discussed ad infinitum, but I could not find answers to my question after a brief search of the forum archives.

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Long story short a Power Commander does help in this area, even with an off the shelf map. However, the best results are always gained with a proper tuning of the bike with the PC. Note there are other devices out there that claim to help but in reality, the two most common and better known are the Power Commander and the Rapid Bike. Both of these are known to help cure the issue and both have their pluses and minuses.

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Thank you Duc2V4. Can you or anyine else comment on whether the PC "helps cure" or "cures" this issue? I would rather not spend $500 or so in hardware and time only to get a minor improvement. I would be very happy however to cure it completely.

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I have a 2005 and experienced similar issues. You might also check out this thread:

 

http://www.vfrdiscussion.com/index.php?/forums/topic/82835-jerky-at-low-speeds/

 

The suggestions I took from that thread and others on this site are:

 
1. Remove slack in throttle cable
2, Adjust idle to 1300/1400
3. Disable PAIR
4. o2 eliminators
5. Sync starter valves
7. Clean fuel injectors?
 
It looks like you've already worked through a few of these. I purchased the Emgo vacuum meters for doing the starter synchronization (#5), but haven't yet done the work. I've heard this can yield big dividends, since low-throttle fuel-metering is exactly what the starter valves are intended to address. There's even a video specific to VFRs:
 
 
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I guess my answer was a little too short to be helpful. IMO, with the PCV alone, without a full tuning may get you better performance that is more livable (based on my experience), perhaps completely satisfactory with doing what RobF suggest but to completely solve the issue, getting it tuned with the PCV installed will gain you the best results.

 

Either get it tuned or get the auto tune module for the PCV, something by the way that is built into the Rapid Bike, and let the device tune itself. This does require using the O2 sensors so you would skip that step in RobF's post. I recently sold my PCV in favor of the Rapid Bike and went back to using the O2 sensors. I've had it for a while now and it did work really well out of the carton but I am planning on doing a little more, like the SV sync, injector cleaning and I'm also going to look into the software and see if I can make some minor tweaks in what changes it makes while running.

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Throttle body starter valve synch, very important for good just off idle throttle response. Have a good look at the condition of your air filter to. Haven't picked up a bad batch of fuel have you? With only 8k on the clock would be surprised if you have an injector issue.

 

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Try synchronizing the starter valves first. Important to have a clean air filter. Then check if bike left the manufacturing plant with O2 sensor electrical connectors the right way round, apparently some units had theirs mounted incorrectly (download workshop manual, search for a thread here explaining how, it's easy to check).

 

 

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I had problems like that too, went with a Power Commander V with AutoTune after doing a starter valve synch, PAIR disable, etc.  It helped but wasn't a complete solution.  Starter valves made a big difference but it was still snatchy.

 

My problem was that the hose clamps on the throttle body boots weren't tightened down, so the MAP sensor got a bad reading and enriched the mixture way too high.  I was getting about 190 km to a tank.

 

Tightened those up, put everything back to stock and it ran great.  Mileage went up to almost 300 km per tank.

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1 hour ago, dawson said:

I had problems like that too, went with a Power Commander V with AutoTune after doing a starter valve synch, PAIR disable, etc.  It helped but wasn't a complete solution.  Starter valves made a big difference but it was still snatchy.

 

My problem was that the hose clamps on the throttle body boots weren't tightened down, so the MAP sensor got a bad reading and enriched the mixture way too high.  I was getting about 190 km to a tank.

 

Tightened those up, put everything back to stock and it ran great.  Mileage went up to almost 300 km per tank.

Thanks for the tip. I solved this the throttle issue on my 03 with a PCIII and map. Butter smooth. My current 07 has been a pig. We did a starter valve sync at the spring ride and it made huge improvement but it still has a slight lag. It makes it hard to pick up the throttle coming out of corners. Makes me feel clumsy(er). I'll be checking my boots next.

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Thanks a lot RobF and others. I will look into doing the starter valve synchronization and O2 eliminators. That's all new to me. Dumb question number 2: by "O2 eliminators" do you mean "oxygen sensor eliminators"? I am starting to frrl a wee bit naughty about all this from an environmental point of view. I will replace my air filter, probably about time anyway.  One thing at a time.

BTW I always use ethanol free gas, unless I am on the road far from home and have to fill up. Fuel consumption seems normal--about 45 mpUSg. And other than the initial abrupt power delivery when rolling on (gently) from full off throttle, the engine runs perfectly in my opinion.

 

Since it took me about 30 years to get around to finally buying a VFR, I plan to keep it a while, so will keep plugging away at this.

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Most of the snatchy-ness is due to the factory o2 sensors and their purpose. Disabling them is a double edged sword. Honda uses them to go into an ultra lean burn closed loop fuel tuning, say about 15:1 AFR, when under light/steady throttle conditions and in 2 valve. On one side, they make for great mpg's and very clean emissions, but on the other side this lean burn causes lean surging and when you move the throttle, you will be going in and out of closed loop fuel injection and lean burn, causing abrupt throttle transition. If you disable them, you will lose the lean surging and snachyness, but you will also lose a few mpgs and gain some exhaust fumes.

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3 hours ago, Wiggie said:

Thanks a lot RobF and others. I will look into doing the starter valve synchronization and O2 eliminators. That's all new to me. Dumb question number 2: by "O2 eliminators" do you mean "oxygen sensor eliminators"? I am starting to frrl a wee bit naughty about all this from an environmental point of view.

 

Yes, "o2 eliminators" is shorthand for any kind of solution that removes the oxygen sensors embedded in the exhaust. Here is one low-tech, low-cost solution:

 

http://www.vfrdiscussion.com/index.php?/forums/topic/20350-make-your-own-o2-sensor-eliminators

 

As to your point of wee naughtiness, that is also correct. A notable portion of the after-market performance mods you will encounter (some of which I have done on my bike) are essentially forms of regulation arbitrage. The manufacturers operate under much stricter legal scrutiny than do owners. This makes it possible for us to "fix" the "dumb" OEM design by circumventing various emission controls designed to reduce noise, hydrocarbons, etc. Everybody consults his own conscience on this, but I do think it's important to be honest with ourselves about what's happening. This particular mod (Power Commander III with o2 elimination in my case) was an easy choice for me, since the altered emission profile is (I believe) modest, and the improved throttle smoothness is notable.

 

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I read years ago that the factories that make catalytic converter's make more toxic waste than internal combustion engines. All the lawn mowers out there spewing un-catted fuel into atmosphere.... And catalytic converter does not function properly until it has reached operating temperature? How many trips are just to corner store, drop kids at school down the road etc.
I don't think a handful of guy's looking for extra power are going to change much!

Sent from my HTC_PN071 using Tapatalk

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I checked my idle speed, 950-1000 on the bike's tach. Manual says 1200+/-100 so that's the next thing I will do, after replacing the air filter.

In the meantime I will just try to ride faster ?

 

Thanks to all for your suggestions.

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I read years ago that the factories that make catalytic converter's make more toxic waste than internal combustion engines. All the lawn mowers out there spewing un-catted fuel into atmosphere.... And catalytic converter does not function properly until it has reached operating temperature? How many trips are just to corner store, drop kids at school down the road etc.
I don't think a handful of guy's looking for extra power are going to change much!

Sent from my HTC_PN071 using Tapatalk



A typical car engine from the ninties will light the cat after around 30 seconds on idle. Now it's quicker due to, among other things, cat size and placement. Short trips are no problem. That lawn mowers are allowed to run ancient engine tech is unbelievable!
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On 6/22/2017 at 11:50 AM, Duc2V4 said:

I guess my answer was a little too short to be helpful. IMO, with the PCV alone, without a full tuning may get you better performance that is more livable (based on my experience), perhaps completely satisfactory with doing what RobF suggest but to completely solve the issue, getting it tuned with the PCV installed will gain you the best results.

 

Either get it tuned or get the auto tune module for the PCV, something by the way that is built into the Rapid Bike, and let the device tune itself. This does require using the O2 sensors so you would skip that step in RobF's post. I recently sold my PCV in favor of the Rapid Bike and went back to using the O2 sensors. I've had it for a while now and it did work really well out of the carton but I am planning on doing a little more, like the SV sync, injector cleaning and I'm also going to look into the software and see if I can make some minor tweaks in what changes it makes while running.

Just an update here. On Saturday I installed a set of used injectors and did an SV sync. The injectors I bought off of eBay and cost me $85 for a set of 4. They were in great condition but I dropped them off at RC Engineering in Torrance California. They charge $24/each to clean and flow test them but that includes replacing all of the o-rings and seals. They did a quick turn around too, 24 hours but I assume that may vary depending on their work load.

 

Since these injectors are for my commuter and I don't like down time, I went with the buy and swap option. Something I'll do from time to time in order to maintain the use of the vehicle due for maintenance/repair. I did a search for the latest and cleanest, as well as least expensive units and purchased those. I'll admit, it is a small gamble but figured worth a shot since the price was good. In this case it turned out great. I have been sitting on my synchronizer for some time now and finally got a chance to use it. When I first hooked everything up and started the bike, the sync was pretty close, just a few minor tweaks and all was good.

 

After everything was buttoned up, I took a short ride and what a difference! Slow speed was much smoother and roll on throttle acceleration had no hesitation! Next step is to get the catless headers ceramic coated and fitted on to the bike, then look at the Rapid Bike software and see what I can do there.

 

Here's the injector cleaning results.

 

RC%20Engineering%20Injector%20cleaning_z

 

And the video of the SV sync.

http://www.youtube.com/watch?v=ySftKcRWgTY

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Wow you went from 7.8% variance, to 0.8% variance! Great stuff!! I keep telling people how important this is, but most of them would rather just waste money on snake oil lol.

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26 minutes ago, CandyRedRC46 said:

Wow you went from 7.8% variance, to 0.8% variance! Great stuff!! I keep telling people how important this is, but most of them would rather just waste money on snake oil lol.

Even with the short test ride I felt a difference. I rode to a job site today and HOLY SHNIKES! what a huge difference. So much better throttle response, I can roll on from about 2500 RPM to VTEC engagement and absolutely so stutter or lag or anything like I was experiencing before. I'm hoping to get those headers in and coated soon and hopefully before the end of July, have them installed. Right now my work project has higher priority as the deadline is in two weeks and it's going to be a tight schedule. Once the project is done, I can go back to the more important stuff :wheel:

 

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Hey Duc,

if I'm reading this right you had the used bought injectors cleaned and installed.

Did you get the originals cleaned, and results for those?

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1 hour ago, boOZZIE said:

Hey Duc,

if I'm reading this right you had the used bought injectors cleaned and installed.

Did you get the originals cleaned, and results for those?

Yep, that's what I did. I have not had the original injectors cleaned but it is something I want to do, more so to see how bad they were but it's not a priority at the moment. When I got the injectors back, there is a sticker on the box that reads 'Install injectors immediately'. When I inquired about this with the person helping me, he called the technician and basically he said as long as you install them within a month or so it should be alright. I didn't query for anything more than that but I imagine is has something to do with the seals mostly, as he did add that if I wasn't going to install right away to put some motor oil on the seals before I stored them away.

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You could always just send them in for analysis. Cheaper, plus you wouldn't have to worry about wasting the cleaning if they sat for more than a month.

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On 7/7/2017 at 6:19 AM, CandyRedRC46 said:

You could always just send them in for analysis. Cheaper, plus you wouldn't have to worry about wasting the cleaning if they sat for more than a month.

I could just send them in for analysis or I could get them cleaned and swap with another VFR owner, which is what I  am doing. Dropped them off yesterday morning about 9AM and by 3:30PM they were ready for pick up. I picked them up this morning and here is the results of my original injectors. They were actually worse than the used ones I bought.

 

RC%20Engineering%20Injector%20cleaning-O

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20 minutes ago, CandyRedRC46 said:

wow dripping and all

And not one but two! These had about 60k miles on them BTW. 

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