Hesitation and ping just off idle on full twist

I am still getting used to my 99 vfr800fi and learning the quirks. I have a new little 'things' that are bugging me.

I just noticed it today, I have 75mi on this tank (I have run 4 tanks of regular through it) and it runs great, but I noticed two things.

1. first noticed a backfire on hard engine braking in first gear as I sloooowly rolled the throttle back on so I dont whip the chain (too lazy to clutch it, I know). It was repeatable one more time.

2. second, noticed that if I crack the throttle hard at idle there is a momentary hesitation and a little ping like detonation. It is very short and doesn't seem to affect anything.

Both things happened around 200degree on the engine temp. I was tooling around the country roads, gunning the engine and running through the first three gears enjoying the sound. The bike has 13.3k on the odo and other than a Rick's R/R (So far so good!) and an aftermarket fuel pressure reg (not verified yet, just what the PO said). I haven't looked at the air filter yet and don't know if there are any 02sensor mods on it, I am not even sure if my Gen5 has them.

Anything to worry about? I need new tires, and I would like to ignore this for a while if it doesn't get worse or if anyone else has had that issue.


Any viffers near Buckley WA? I would like to listen to yours, I am not sure if I should be able to hear or am hearing valves clicking. I am the type that cannot enjoy riding without ear plugs because I fixate on every little sound.:frusty:

 

Aftermarket or modified exhaust can cause the backfiring you describe. You also may have an exhaust valve leaking a little.
The ping may be telling you the bike wants a little higher grade of gasoline.

 

Stock exhaust. I will try plus next tank.

does my 99 have an 02 sensor, closed loop?

 

Does yours have the plastic Condom or thin mirror stems ?

If its a '99 build then probably not, O2 Sensors and Cats were introduced on the MK2 update in 2000.

 

My 98 has a TBR full exhaust and it has some little hesitations here and there and usually after start up, but I am hoping that a PCIII will fix that when I can afford it. You just have to be a little more careful when working the throttle and use the clutch when you need it. Mine will pop a little when downshifting too, but no big backfires. I run 91 octane in my bike all the time as well.

 

Hesitation just off idle on full FAST twist

Im an owner of a '99 VFR 800 FIx and I have the exact same problem described on the thread title. I have searched around the forum but haven't really found any problem solving replies, or closed threads. Please do link up if you do know of resolved threads!

Anyway, a bit on my particular case:

My bike hesitates and is slow to react/stutters on FAST throttle blips from idle or when downshifting and fast rev matching. (by fast I mean a little bit faster than you would normally open/blip throttle when rev-maching during downshifts) My mechanic said that all FI bikes will hesitate a little if you open gas REALLY quickly... this sounded like BS to me; if anything a few milliseconds lag should be normal but there should be no hesitation upon fast throttle openings, at least not to the degree I'm feeling.

During idle, if you yank the throttle open from fully closed really quickly it will stutter badly and almost seem to stall and not rev up at all until 3-4 seconds later.

- Stock exhaust
- TFI (a simple PowerCommander that has 3 knobs for adjusting engine performance at low, med, high rpm's)
- Resonnace box removed
- New spark plugs
- Air filter cleaned
- Valves checked (or at least I think they did!!! Who can u trust these days??!?!?)
- 50,000 km


If you roll gas smoothly and blip slowly, no problems, bike isn't lacking power, or running rough... everything seems to be going well, no surges etc.

I've read about possible things to do:

- Throttle body sync (only VTEC???)
- PAIR valve system cleaning?
- Any other suggestions/solutions if anyone can relate???


Thanks in advance guys!


Vsssssss

 

The little ping tells me your a tad lean on you fuel map in that rpm range. Popping thur pipes on decel is also a lean trait. Yes you could run a higher octane as a bandage. Find someone to check the fuel mapping. A/F ratio can be lean at idle of 15.5. and as rich as 13- 13.3 on top end. Depends on what your motor wants.

That's where I would start. You need to know your A/F for a good running machine. Experimentation is the only way to feel it, unless you have a dyno.

 

any more suggestions?

 

Hi All,

After getting my bike dyno'd it was stalling when cold. I found some articles on the "Cold weather idle" on this forum.

I did a dodgy to get it running ok (as I could not adjust the cold weather idle).

My bike was revving at about 2000 because of this.

Ever since I did this the bike was coughing and spluttering when I gave it a good twist from idle. There was a hesitation.

Finally I removed the airbox to get to this bastard adustment and it is now ok. Cold start is idling at around 1500rpm.

Since I have made this adjustment the hesitation/spluttering has gone away. The bike is heaps smoother.

I only mention this as I thought I might need the valves done which is labour intensive or costly if you get someone else to do it.

http://vfrworld.com/forums/mechanics-garage/29099-cold-idle-adjustment-video-00-01-a.html

BTW: This is a bugger of a job. I have found that if you remove the cones from inside the airbox you can move it up enought to get the vice grips on the shaft of the cold idle adjustment. Otherwise it just spins.

Its made a massive difference. Bike is now awesome again

Disclaimer: I have read somewhere that honda don't recommend you adjust this.

 

I had a similar prob with mine about a month ago. Started very suddenly pulling out of a petrol station - gave it a handful and it just wasn't happy. I was scared I'd put in the wrong juice at first! I think I found out what the issue was though. Last week it made a horrific noise and when i got back home I found the downpipe had sheared off! If you've still got the stock downpipes on there I'd suggest looking to replace them. I've been looking around at a few forums and its pretty agreed that they only last 30-40k miles.