2007 vfr 800 vtec - cold start not working.

Had another cold morning here in MI. Bike started and the RPM dropped as it has been lately, and finally it stalled at ~800rpm 5 seconds after startup. Tried to get it to restart and it was resistant. Gave throttle and it finally fired but was very obviously running on less than 4-cylinders. Finally, with persistence and a fair amount of cranking/throttle, all 4 cylinders came to life and it started warming up properly.

So, just another layer to my personal starting onion. I did notice that when cranking the dash lighting dropped out. I wonder if its not a bad battery? Seems my voltage was dropping quite aggressively. But, I see from your notes you added a new battery and it didn't help the issue?

Completely stumped and frustrated at this point!

 

Yes, I had a new battery installed just before this problem started. The biggest clue to the battery being kaput is that the clock and trips would reset, such was the voltage drop on starting.

I find it odd that the bike starts fine and then eventually sorts itself out. The one thing that I haven't checked is the coolant sensor. It's hard to get the multimeter to the connections to test. Maybe I'll trace the wires back to the loom and check it's resistance values there. I don't fancy taking off the throttle bodies unless I really have to.

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Would you believe the bike has been starting fine recently. I'd like to say I know why but I can't. Last thing I did recently was give the wax unit a couple of turns on the adjustment screw. This didn't solve the problem but it meant that it idled at 1000rpm instead of 800 until it finally sorted itself out and jumped up to 2200rpm. Once warm it would drop to 1400.

That was a week or so ago and I've since noticed that it now starts and stays at 2000-2200 rpm as it should until warmed up.

Conclusion. No idea. This problem started as the weather grew colder in September last year, now the reverse is happening but ambient temperature has still been on the cool side here 9-13c. I did notice that after turning the screw that if the bike started at low rpm the jump to 2000 after 10-15sec was more dramatic whereas before it would creep up. I still suspect there was some 'sticktion' occurring.

I've since taken half a turn off the wax adjustment just so the starter valves close a little earlier

Anyhow I'm off on a big trip today. I'm leaving Shropshire and heading south to meet friends in London and then we're off to Arnhem in Holland. Its my first big trip on the VFR. I'll post some photos on my return.
John

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When you get back, try cleaning the starter valves and ports with carb cleaner. Then lighly lube with a thin oil such as sewing machine oil. The linkage should move freely and without any pressure. Check for bent rods or plates for the starter valve system.

Gilkeyb,

Start a new thread for your issue. Post everything you have tried and done. A bad battery connection or a frame connection can contribute to your issue. If you even remotely suspect a bad battery, get a new one. Then either follow my posts on charging system diagnostics or you can use the drill. Make sure beyond a doubt that your charging system is working before syncing the starter valves. The bike needs a stable electrical source to make syncing easy and correct.

 

Back from Arnhem. No cold start issues. Plenty of problems with riding in the rain though, but that's for another thread.

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Just an update. No issues with cold starting through the summer right up to last week when the problem returned. I can't say I've had any bright ideas as to the cause.

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Would love to see if a new wax idle cures it but like you say they're not exactly cheap (Although the chaps in the States seem to be able to get them for buttons compared to us poor Brits)

For the record; I have exactly the same issue. Ambient temps of 5 degrees celcius and below and it'll chug at low revs and even stall on startup unless you feed her throttle. Fast idle otherwise works fine.

 

Yep it's just a case of manually feeding the throttle till she warms up a bit. I could be tempted to buy a new wax unit if I could guarantee that it would fix it. I'll live with it

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So now that it's got truly cold here in Blighty I thought I'd update.

Basically; sorted! I balanced the starter valves, doused the linkages and wax idle in WD40 and checked everything moves freely, chucked in a fresh set of sparks (They were only on 16k but were a bit sooty) and ran a tank with BG44K (The good stuff garages use, not Redex snake-oil) and voila. Zero degrees freezing and she starts and fast idles like a dream.

 

Interesting. I've done all the lubeing so I'll look at the spark plugs and find that fuel additive.

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Well I think I can categorically state, it's the PAIR valve mod. I had mine re-enabled for a while to do some MPG testing so I thought I'd re-disable it. I did wonder to myself as I was doing it if it would provoke the cold start issue and lo and behold the next day she spluttered at low rpm on startup. Tweaked the idle adjuster to raise it and it's not quite as bad.

And the kicker? Re-enabled the PAIR valve.... starts up no problemo. I haven't noticed any sort of stellar improvement with the PAIR disabled tbh, the only thing that bugs me is the stupid 'plonk' noise from the valve at zero to fractional throttle. Guess I'll leave her as stock and be happy with easy starting.

 

I think I experimented with that last year as my pair is currently disabled. I don't recall it made any difference to my bike. However I think its worth another go just to confirm.

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Step one, remove all the emissions crap (pair, evap, flapper, snorkel, o2 sensors etc.). This is also a good point to ensure that your injectors are up to par by removing them and sending them away for ultrasonic cleaning and analysis.

Step two, Synchronize the throttle bodies.

Step three, while tank is still up and airbox is still off, tighten up the wax unit.

Step four, leave the tank up and airbox off and allow bike to cool down for 24 hours.

Step 5, start up bike and allow to high idle to 150F. At this point turn down the wax unit until it settles down to the factory spec 1100 +/- 100 rpm range.

Step six, allow bike to cool down for another 24 hour period and start up test again to make sure the high idle is in an acceptable range and that it slows down by 150F. You may need to try this a few times and adjust the idle with the idle cable knob to get it right.


If all this checks out (which it should), you're good.

 

So I unblocked the pair pipe yesterday. And the started the bike. Air temp was low but the bike stated okay hesitated and picked up a high rpm in a slightly lumpy manner for a second or two before settling at just over 2k. A good improvement and no throttle intervention from me.
I left the bike outside overnight and tried again today. Air temp was 3°. Again started fine with no intervention.
I then took the bike out for a 40 mile ride and it might have been my imagination but the engine felt so smooth and eager. The low speed lumpiness was present again but taking everything thing into account I think I'll leave the pair enabled for a bit longer.
One thing I had to do when I returned home was lower the tickover as it was nearer 1500rpm. I might also have to turn down the adjustment on the wax unit which was a turn and half higher than standard due to previous meddling.
Now I tried all this last year and it didn't seem to make any difference except then I only tried one startup.

 

I have a feeling if you re-balance your starter valves with the idle set right for the PAIR re-enabled it'll all start as it should. That's what I've found.

Some day I might splurge on a PCV to sort out the low speed lumpiness instead of the PAIR mod but for now I can live with it. I was going to try a throttle tamer too but they're ruddy expensive for what they are.

Perhaps it's just an unfortunate twist of fate that only (thus far) thee and me have to live with in our particular bikes or maybe it's a quirk of the British weather (damp, cold etc) that causes this. Who knows, it wouldn't be a Viffer if it didn't have a 'personality' eh :smug:

 

You're probably right. The SV's were done only a few thousand miles ago by the previous owner but it wouldn't hurt to look again.
I only disabled pair because of low speed snatchiness and that was during the warmth of the summer.

 

What do the pair valves have to do with starter valve synchronization?

 

Directly; nothing. But enabling/disabling the PAIR requires adjusting the idle speed, which in turn may affect the starter valve sync if already done. I'd rather reset to a known calibration than spend the time balancing only to have slightly knocked it out tweaking the idle after she's all buttoned up.

Dashboard read minus 4 this morning but in reality it was minus 2, I think the temp probe is a bit out sometimes. She started up though, slight amount of low rev 'bogging' but at that temp I can't begrudge it.

Commute was a tad nippy on the old fingers I can tell you!

 

An update on my bike. The pair has been re-enabled all week and the bike has started fine every time. The high speed idle was a tad high at 2500rpm and tick over when warm was slightly high at 1500 rpm.
During my previous fiddling I'd turned up the wax unit by 1½ turns. So today I wound that back by 1 turn. Bike still started fine but bogged down more than before. I wasn't entirely happy so turned it back by ½ turn. So in effect I'm running 1 turn up.
Warm tickover is now 1200 rpm. The fast idle is still just over 2000 rpm.

So hopefully this is the end of the story for me. Solution was re-enable pair and give the wax unit one turn increase.

Hope this helps someone.

 

I am still chasing my tail on this. At this point my VFR has 26K miles and I decided to do a little bit of preventative maintenance.

-New Iridium plugs (still had the stock plugs before)
-NEW Fast Idle Wax Unit
-NEW T-stat (figured while I was in that deep I might as well)
-fresh coolant
-PAIR Valve Re-enabled (had a ball bearing in it that I now took out).

This provided NO relief for the issue. I was hoping the new FIWU would solve the problem but, alas, that was wishful thinking.

My most recent attempt was to disable my PC3. My suspicion is that the bike is blubbering rich one cold starts. I thought that could be caused by a faulty PC3 or a bad tune. But, that did not alleviate the issue (it was a shot in the dark).

Now I think it could be something related to spark. One of the things I wonder is if my battery is weak. Thus it provides enough energy to crank the bike but the voltage drops to the point that I get bad spark. I did take the battery into a autoparts store and they said it was "bad". But, I have capacity checked it and it seems OKAY. Plus, I know people hear have tried new batteries with now positive effects.

It is getting warmer here, so the issue will most likely go away soon. At this point I may strongly consider adjusting the wax-unit as other people have had to do. But, there MUST be a solution that is better than that. I just can't find it