cold start problem

[Smee]

Hi folks, I know it's not cold yet but my 2015 pcx will not idle when started from cold. Not a massive issue I agree but an inconvenience nonetheless. Was fine all summer till a week ago. Starts fine but until it's warm it just dies which is a pain when first starting my journey(s). Also noticed mpg dropped very slightly and stays constant.

Can't get dealer to look at it for a while so wondered if anyone has had same problem?

Cheers

[gn2]

Start and ride away immediately.
No need to leave it idling after first start.

[j.d.b.]

Might take a look at the spark plug. If it's worn, replace it. If it looks good, try gapping it to the wide side of the spec. for a bit hotter spark. A cold motor has a higher fuel demand. the controller will enrichen the mixture and a hotter spark will help light it until there's some heat in the chamber.

[Smee]

Will check plug, thanks. In fact I'll treat her to a new one although she had one a couple of months ago.

I do ride away immediately. It's when I get to the next junction or two that it's a pain. See a gap, go for it and .....and...fire's gone out......stop. Foot down, rear brake on, apply starter and away again. It's not cool man.

[Oyabun]

Well, Gn2 just blessed us with his generous words of wisdom.
While it is true that he can ride away after start it is still not a solilution for the OP's problem what is most likely a sign of a malfunction of the bike.
As it is a cold start problem on a relatively new biked I'd be very surprised if it would be a spark plug issue. It rather sounds to me like a sensor issue (cylinder head temp or coolant temperature) but given the fact that the bike is a 2015-model it is most likely still under warranty - so I'd get to visit a Honda service as soon as I can to avoid any further issues before letting the forum to diagnose it over the web.

[j.d.b.]

I think ya got something there, Oyabun. The OP didn't say he was already riding it (getting heat in it) when it was dying out. Say, Smee, has the MIL(check engine) lit up at all on the bike when this happens? Definitely a problem in there to be addressed.
Post back, yeah?

[Smee]

Hi guys. I'd tend to agree re some sensor fault maybe. After less than a mile its warm and doesnt happen. Just annoying. Always a problem trying to synch dealer availability with my own but will try new plug over weekend and post back. No check engine light seen. Only other thing possibly related is that av mpg has gone down just a smidgeon on my regular commute and doesnt budge whether I thrash it or run it smooth which ties in with a possible sensor problem. It never budged much before but was always affected by a long incline or headwind. That doesnt happen now.

[j.d.b.]

Cold weather typically lowers fuel economy on all IC motors. Unless it's a ton, it's to be expected.
Did you look at the gap on the plug, yet? For grins, you could gap it to the wide side of the spec and test again. Easiest thing besides maybe you got a load of less-than-useful fuel? With no MIL there's likely no code to point the way to potential trouble. It's also possible the thermostat is hanging a bit open, delaying warm up beyond the "closed loop timer". The system has a timer as to when it starts using the O2 signal to control fuel(ending enrichment and controlling to stoich which is pretty lean). I don't know how long their timer lasts, so it's just a guess. These are things I've seen in FI cars which may not closely apply to these FI bike systems. Cars will set a MIL for "too long to reach temperature". These bikes don't have full OBD (for instance, they don't have a cat monitor) so they might not know they aren't warming up, either.
Just a few guesses until you can get some professional involved.

[Smee]

Thanks for the responses guys. New plug, stll same so will have to visit dealer when they have a slot. Will keep you updated.

[Oyabun]

As you have changed the plug already - how was it reading? Rich, with lots of carbon deposits or rather lean looking light color?
It can help the further diagnosis of the issue

[Smee]

Ok, diagnostic machine reports an injector fault so waiting for a phone call when they have the parts. It's a big job apparently, all the back end has to come off. The plug looked normal, maybe a little lean. Anyway lets hope it's sorted soon.

Thanks for the replies guys.

[Oyabun]

Good to hear it seems you're on the way to sort it. Keep us posted.

[helenswain.com]

ugghhh,

i was hoping not to read something like that.

I'm new here (Hiya) and just registered to try and find a solution to my cold start problem on my 2012/3 bike. It has been running fine until a couple of months ago. It was due it's MOT so i mentioned it to the guy at the time and he stuck a new spark plug on it, saying it sounded like that could be the problem. It wasn't as it still kept happening.
Weirdly, it's not every time it starts from cold, but probably 9 times out of 10. Exactly the same faults as the creator of this post. It starts, runs lumpy then dwindles and dies. I was always under the impression that a bike should be run to warm before riding so have always started it, moved it out the garage, put coat/helmet/etc on before actually riding it away. Now it's super annoying as I have to stand there with one hand on the throttle to prevent it cutting out!!

Anyway, I was hoping to find a fix on here without having to resort to an expensive honda dealer trip (out of warranty).

[iceman]

Many start and move off even in cold temps - not just scooters but proper bikes (I see them do it at work, turn the key and they are off!). I would not do that nor leave it running for minutes, but in my view good to leave it at least 5-10 seconds to get the oil flowing over the metal bits before moving off - especially those that go WOFT

[you you]

Many start and move off even in cold temps - not just scooters but proper bikes (I see them do it at work, turn the key and they are off!). I would not do that nor leave it running for minutes, but in my view good to leave it at least 5-10 seconds to get the oil flowing over the metal bits before moving off - especially those that go WOFT

Wots a WOFT?

[WhiteNoise]

Ahhh I'm thinking Wide Open Full Throttle. What's in/on yer mind 2yous?

[helenswain.com]

Smee,

I'd appreciate when you've had the work done to let me know if it's fixed and how much it was?

Thanks bud

[you you]

Ahhh I'm thinking Wide Open Full Throttle. What's in/on yer mind 2yous?

Not a lot usually. Wouldn't a wide open throttle be a full throttle?

[you you]

Wide open first thing?

[Smee]

Quick update. Fuel injector replaced but a new fault code showed up. Rather than wait an hour for engine to cool down before checking cold start they cleared the fault and said to test it. They did say if still a prob then they'd replace main ecu.

Well, next morning full of hope, press the button.....nope, same. In fact it's worse.. won't idle till warm, very lumpy till warm. Dealer has ordered new ecu so waiting for a phone call. Will update when more news.