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Discussion Starter · #1 ·
I've had problems starting my bike on cold (less than 60f) days since I put on my slip-on exhaust. The bike would turn over for 2-3 seconds, and the whole ECU would reset and I'd have to wait for 1-2 seconds before I could try starting again. I always assumed it was a bad battery.

I've tried 3 new batteries and the only way it would ever start on a cold day is if it was a brand new battery or fresh off the charger or hooked up to a car battery (with the car off). I always keep it on a battery tender over night.

Anyway, a couple weeks ago I thought I'd crack open the throttle as I started it and when I did that, the ECU never reset and the starter kept on cranking the engine and the bike finally started, always on the first or second try. It used to take 20 minutes to get it running some times.

Any ideas what could cause this?

-Is this just normal?
-Could it be the fuel map is too lean?
-Bad/weakening fuel pump?
-Isn't it odd that a jump from a car starts the bike too?

I should also point out the cat/exup are removed and I'm running [FLUX]'s full system tune which rips like a bat out of hell once the bike starts.
 

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have you tried the full elec system check?
 

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My guess is the fuel trim settings down low. I had a pretty heavily modified Arrow map I was running for awhile. I kept making small tweaks to it and I eventually ran into the same issue. I couldn't get it to idle right and it stalled a lot unless the bike was almost fully warm. I got so frustrated I deleted the map and went back to the Arrow and she fires up everytime. I can't waut to get a good dyno tune this spring.
 

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Discussion Starter · #5 ·
have you tried the full elec system check?
What's that?

when was the last time you did a TPS reset?
I had this same thing for a while, and when I removed the EXUP and and other junk and did a TPS reset...it went away.

Or a loose ground maybe?
I have done it, but I guess it can't hurt to try again. I'm leaning towards a fueling issue and less an electrical issue. I thought maybe the extra power from a fresh battery or car jump was just helping the fuel pump out a bit.

My guess is the fuel trim settings down low. I had a pretty heavily modified Arrow map I was running for awhile. I kept making small tweaks to it and I eventually ran into the same issue. I couldn't get it to idle right and it stalled a lot unless the bike was almost fully warm. I got so frustrated I deleted the map and went back to the Arrow and she fires up everytime. I can't waut to get a good dyno tune this spring.
Yeah, I thought I might try bumping up the fuel a bit, but after its running everything is sooo smooth I don't want to hurt it. I thought I'd try to figure out what RPM the starter motor turns the engine and richen up the mixture a bit, or maybe along the whole range below the idle RPM.

Glad to hear from you KEGS, I think our setups are pretty similar. Maybe I can steal your tune when you get it made.... :whistle:
 

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well check batt voltage
stator output
and regulator output
 

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so if you got a uber charged good battery it will start normally right?

but if the battery is just good but not uber charged its hard for it to start?

got any elec mods? HID's?

if its not that it has to be in the fuel mapping, fuel delivery, or sensor related
 

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What's that?

I have done it, but I guess it can't hurt to try again. I'm leaning towards a fueling issue and less an electrical issue. I thought maybe the extra power from a fresh battery or car jump was just helping the fuel pump out a bit.

Yeah, I thought I might try bumping up the fuel a bit, but after its running everything is sooo smooth I don't want to hurt it. I thought I'd try to figure out what RPM the starter motor turns the engine and richen up the mixture a bit, or maybe along the whole range below the idle RPM.

Glad to hear from you KEGS, I think our setups are pretty similar. Maybe I can steal your tune when you get it made.... :whistle:
I'll be updating my thread with the dyno numbers and I'll send you my tune. I'm hoping to do this by June at the latest. Michigan winters suck...bikes just sitting in the corner covered up on stands. Haven't got the ambition to mess with it much this winter yet.

I'd try adjusting the Idle stepper motor. It's in the service manual I think somewhere in section 10. Also might want to check the vacuum lines between the map sensor and throttle bodies. Vacuum leaks can cause idle and stalling issues. Hope you get it sorted soon man.
 

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Discussion Starter · #11 · (Edited)
so if you got a uber charged good battery it will start normally right?
yes, or if I jump it.
but if the battery is just good but not uber charged its hard for it to start?
yup
got any elec mods? HID's?
nope
if its not that it has to be in the fuel mapping, fuel delivery, or sensor related
I'll be updating my thread with the dyno numbers and I'll send you my tune. I'm hoping to do this by June at the latest. Michigan winters suck...bikes just sitting in the corner covered up on stands. Haven't got the ambition to mess with it much this winter yet.

I'd try adjusting the Idle stepper motor. It's in the service manual I think somewhere in section 10. Also might want to check the vacuum lines between the map sensor and throttle bodies. Vacuum leaks can cause idle and stalling issues. Hope you get it sorted soon man.
I'll see what I can find.
Could be a stepped motor adjustment issue but I seem to remember reading in the owners manual a mention that opening the throttle may be necessary in cold weather during start up.
What's cold? 50°f? I never looked, but now that you mention it I found this:

In very cold conditions, part
open the throttle to aid cold
starting. Return it to the
closed position once the
engine has started.
 

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Discussion Starter · #12 ·
when was the last time you did a TPS reset?
I had this same thing for a while, and when I removed the EXUP and and other junk and did a TPS reset...it went away.

Or a loose ground maybe?
I just hooked up Tuneboy again, and the TPS reset seems to be for Sagem ECU, not Keihin ECU. I don't have that option, so I assume I must have the Keihin ECU.

Did you mean reset the ISCV? If I try that, it just says "unsupported".
 

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I just hooked up Tuneboy again, and the TPS reset seems to be for Sagem ECU, not Keihin ECU. I don't have that option, so I assume I must have the Keihin ECU.

Did you mean reset the ISCV? If I try that, it just says "unsupported".
In TuneBoy you want to use the "reset adaptations" feature. Do this on the TuneBoy dash program, not in the TuneEdit side of the program.
 

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I'm having the same exact issue as you.

FWIW, I didn't have this issue until winter season. After I've rode it for a while and parking I usually don't have an issue restarting the bike normally (without needing to crack the throttle open).

Can someone chime in on the mechanics on why cracking the throttle open upon starting helps for cold motors vs not needing to do this when warm?
 

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When cranking a cold engine, heat(which aids incombustion) is created merely by compressing the air in the cylinder. Opening the throttle some will allow more air in, and increase the effect of this because you are compressing a larger volume of air into the same space, thus creating more heat. Also, given that you have a greater volume of air/fuel mixture now in the cylinder from the open throttle, you obviously will get a "bigger bang" to get that crankshaft spinning initially. Basically the 3 key ingredients for combustion are, 1. oxygen, 2. Fuel, 3. A source of ignition/heat. You're basically lacking in this last one on cold start.

Obviously when the engine is a little bit warmer, there is enough heat already in the engine to produce efficient combustion. Hope that helps.
 
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