Won't start when cold
Elite HDF Member
Joined: Apr 2007
Posts: 4,919
Likes: 23
From: Seattle, WA
When the bike starts, there is an Idle Air Control system that is a routine run in the ECM ... on startup, the EFI system has the throttle butterfly plate closed off, shut ... but, there is a little passage that allows air in ... the IAC system has a little servo operated valve that meters the proper amount of air for the AFR (air/fuel ratio) on startup ...
As temperatures drop, the AFR is programmed to become richer ... so, it is possible that there are a few culprits ...
- could be the temperature sensor ... as mentioned in a post above, there is a head temp sensor--but, I think there might be another one that senses ambient air temp ...
- could be an issue with the IAC or the servo that meters the air ... as I understand it is sometimes possible that the air passage can get debris in it that blocks the air ... when you remove the A/C and open the butterfly valve up, there is a little hole at the top of the trottle body ... a shot of carb cleaner up in there should dislodge or clean out any debris ...
- could be an intake leak at one or both of the manifold gaskets where the manifolds contact the heads ... the way to test for a leak is to spray a little propane gas or some other volatile hydrocarbon (carb cleaner, WD 40, etc.) around the manifold gaskets when the bike is idling ... if the motor speed revs a little, it indicates a leak ...
- another thing it could be is something with electrical system/ECM (or coil) to do with the proper amount of voltage/amperage at the spark plugs ...
Seems like I might be forgetting something ... if I think of it I'll post up later ...
When the temperatures are relatively warm, any of the above may not cause problems ... but, as the temperature drops, the motor is a little more sensative to these types of things ...
Good luck and post up the resolution if you're able to get it figured out ...
R/
'Chop
As temperatures drop, the AFR is programmed to become richer ... so, it is possible that there are a few culprits ...
- could be the temperature sensor ... as mentioned in a post above, there is a head temp sensor--but, I think there might be another one that senses ambient air temp ...
- could be an issue with the IAC or the servo that meters the air ... as I understand it is sometimes possible that the air passage can get debris in it that blocks the air ... when you remove the A/C and open the butterfly valve up, there is a little hole at the top of the trottle body ... a shot of carb cleaner up in there should dislodge or clean out any debris ...
- could be an intake leak at one or both of the manifold gaskets where the manifolds contact the heads ... the way to test for a leak is to spray a little propane gas or some other volatile hydrocarbon (carb cleaner, WD 40, etc.) around the manifold gaskets when the bike is idling ... if the motor speed revs a little, it indicates a leak ...
- another thing it could be is something with electrical system/ECM (or coil) to do with the proper amount of voltage/amperage at the spark plugs ...
Seems like I might be forgetting something ... if I think of it I'll post up later ...
When the temperatures are relatively warm, any of the above may not cause problems ... but, as the temperature drops, the motor is a little more sensative to these types of things ...
Good luck and post up the resolution if you're able to get it figured out ...
R/
'Chop
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Joined: Feb 2011
Posts: 85
Likes: 1
From: South Korea
Well, it was 39F this AM and she fired up after 2-3 rotations. I think maybe they didn't charge it before they installed the battery. I hope, anyway. We'll see on the really cold mornings.
BTW, a 15 minute ride at about 20F wakes you up better than a pot of coffee. I don't mind, except when I lose feeling in my finger tips. I need heated gloves, but I'm too cheap to buy them.
BTW, a 15 minute ride at about 20F wakes you up better than a pot of coffee. I don't mind, except when I lose feeling in my finger tips. I need heated gloves, but I'm too cheap to buy them.
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Joined: Jan 2007
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From: along the shore of Mishigami
A bit of a warning, those 15 minute rides at freezing or below will form condensation in your engine/trans cases. I realize it's a beotch at those temps but the engine has to get really warm to evaporate the water that is gettig mixed in the oil. When you pull the dipstick and its milky then there is water. You can you use a 10W40 oil when temps are regularly below 40*F. That's recommended by HD.
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Joined: Feb 2011
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From: South Korea
A bit of a warning, those 15 minute rides at freezing or below will form condensation in your engine/trans cases. I realize it's a beotch at those temps but the engine has to get really warm to evaporate the water that is gettig mixed in the oil. When you pull the dipstick and its milky then there is water. You can you use a 10W40 oil when temps are regularly below 40*F. That's recommended by HD.
Road Master
Joined: Apr 2008
Posts: 931
Likes: 3
From: England
I bet it's in the cold start circuit of the ECM, may even go back to the cylinder temp sensor is out of wack. Not sending a signal to the ECM to enrichen the fuel spray/mix (Injector pulse). The sensor is on the front cylinder, left hand side, I think it's in the head.
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From: Mid West
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Joined: Jan 2007
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From: along the shore of Mishigami
Hey notnutts, the length of ride to warm up that motor could make you change your name to numb nuts. In the spring when I ride the beast I try to get in a 30 to 45 minute ride to get the oil good and hot. Maybe on the milder days you can get the longer rides in. Perhaps you could find some gloves with seperate liners for them. Does your local dealer have any catalogs for motorclothes and order out of it?
Stage II
Joined: Sep 2019
Posts: 2
Likes: 1
From: USAG HUMPHREYS, S.KOREA
Ok, I ride an 05 Dyna FXDLI (fuel injected). It never wanted to start when it was cold out (below 40F or so). I figured it was just an old battery. I took it in for another problem (MAP sensor) and had them replace the plugs and put in a new battery. Went out this AM, temp was around 32F, and it didn't fire up. It acted just like before--turned over but didn't catch. Once it warmed up outside, it still didn't fire up, but it sounded like I'd worn the battery down a bit. So, is it normal for bike not to fire up when its this cold? I need the bike as a daily driver this winter (except when the roads get icy--I'm not that stupid).
Right now I have the battery on the charger. I'm gonna put it back in tonight and see if it fires up in the AM. I thought maybe the shop didn't charge it all the way before they put it in. What do you guys think?
BTW, I'm a GI stationed in Korea, so my bike repair options are limited. The Korean joint I take it to seems pretty good, though (Bison choppers). Most of the GIs stationed here take their bikes there.
Right now I have the battery on the charger. I'm gonna put it back in tonight and see if it fires up in the AM. I thought maybe the shop didn't charge it all the way before they put it in. What do you guys think?
BTW, I'm a GI stationed in Korea, so my bike repair options are limited. The Korean joint I take it to seems pretty good, though (Bison choppers). Most of the GIs stationed here take their bikes there.
Current temp 33° put her iside for 10min and she fired right up!
When you wanna ride in the winter at USAG Humphreys and your bike hates cold starts!
Last edited by Brandon Pohler; Jan 18, 2020 at 11:31 PM.