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Cold Start issues


triharder

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So my 2007 VFR is sitting at almost 46k and has treated me well since 6k when i bought it in 2011. 
 

When i start my bike when its cold after sitting (for a while or for 8 hours while i'm at work),  regardless of 40 degree day or 80 degree day and you don't let it warm up to 125 degrees or so and shift in gear and touch throttle it revs to 4500 rpm until it hits 125 degrees.

1) Its fine if you don't shift it gear

2) no binding, sticking or reason the throttle would be doing this (the throttle body doesn't stick and throttle cleanly snapps back)

3)  Won't do it unless you shift in gear and touch throttle (leaving work at 11pm at night)

4) won't do it if you justs let it warm up over 125 degrees.

 

Anybody ever hear of this?

If you try to go with it revving to 4500 once you release the clutch she dies out and damn near stalls out.  Kinda interesting to ride around that issue.  

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1 hour ago, triharder said:

So my 2007 VFR is sitting at almost 46k and has treated me well since 6k when i bought it in 2011. 
 

When i start my bike when its cold after sitting (for a while or for 8 hours while i'm at work),  regardless of 40 degree day or 80 degree day and you don't let it warm up to 125 degrees or so and shift in gear and touch throttle it revs to 4500 rpm until it hits 125 degrees.

1) Its fine if you don't shift it gear

2) no binding, sticking or reason the throttle would be doing this (the throttle body doesn't stick and throttle cleanly snapps back)

3)  Won't do it unless you shift in gear and touch throttle (leaving work at 11pm at night)

4) won't do it if you justs let it warm up over 125 degrees.

 

Anybody ever hear of this?

If you try to go with it revving to 4500 once you release the clutch she dies out and damn near stalls out.  Kinda interesting to ride around that issue.  

Can't believe you started the sentence with "So". :wink::goofy::beer:

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Just FYI; cold start fast idle is controlled by the wax unit, which is connected to the coolant system for the engine block. When cold, the wax unit holds the starter valves open, and as the coolant heats the wax unit changes length and eventually allows the starter valves to rest on the idle adjuster screw. If the small coolant hoses or the coolant passage within the wax unit get blocked the high idle can persist even though the engine is warm, so I'd be checking for free flow there first. The manual suggests NOT adjusting the screws on the wax unit because the length is critical to the speed of the fast idle and to allowing the starter valves to eventually rest on the idle screw.

 

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My bike used to do the same thing in super cold weather, but, it would only happen in gear just as the clutch Leger switch would trip. The bike would Rev itself up even with my hand off the throttle. From what I've heard it's some anti-stall programming in the computer. 

 

Since I instapped my rapid bike, it no longer does it. 

 

As many suggested, it was as the fast idle wax unit. I replaced it ($120 canadian pesos and a lot of cursing) only to find out that the one I replaced was still good

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7 hours ago, TriumphTraitor said:

My bike used to do the same thing in super cold weather, but, it would only happen in gear just as the clutch Leger switch would trip. The bike would Rev itself up even with my hand off the throttle. From what I've heard it's some anti-stall programming in the computer. 

 

Since I instapped my rapid bike, it no longer does it. 

 

As many suggested, it was as the fast idle wax unit. I replaced it ($120 canadian pesos and a lot of cursing) only to find out that the one I replaced was still good

 

Interesting same problem.  I thought maybe ECU related but wanted some others to let me know if they've seen this too.

(my wax unit is fine,  as the bi-metallic spring is not going to wear out within 46k and time doesn't wear out the effectiveness of  spring,  and I regularly flush my coolant lines)

also it doesn't do it unless its in gear. 

 

Thanks guys,  keep the suggestions going. 

 

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Is your warm idle at 1200rpm?

The 8gen and if I remember correctly the 6gen is the same, that is, when not in neutral and you release the clutch, at the point where the clutch switch de-activates, the ECU will increase engine RPM by 250rpm. If you do this with a cold engine the RPM increase can be approx 1000rpm. It's an anti stall assist function.

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No, my warm idle is closer to 1400 rpm.  as i watch my volt meter and anything under 1400 on tach (haven't checked per meter since valve sync in a few years) and it will drop to 13 if the idle isn't around 1400 (also the motor just doesn't sound correct).

 

Its funny its touted as a anti stall assist.  As when you actually attempt to drive forward the thing gets all confused under load and will dam near drop out the throttle,  YOu'd be better off with it not increasing and therefore you had to advance the throttle to get where you needed to be. 

 

I don' remember it ever happening before sitting and makes the bike scream at 4500 rpm in the parking lot/work before i leave when people are walking by me.  (embrassing).  Then i let the clutch out and the thing falls on its face.   (makes starting out interesting)

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In the interest of attempting to start with something that's simple to check, it sounds like your VFR's ECU is trying to implement its anti-stall assist function but failing to do it properly.  My guess would be one (or more) of the input parameters that the ECU uses to control this function must be coming into the ECU as a corrupted or bad input, maybe due to something as simple as a corroded wiring harness connector.

 

Maybe give the bike's wiring harness a good going over to see if any of the connectors or wiring are looking problematic. 

 

Obviously your VFR hasn't always had this problem so I'm just trying to guess at something that might have changed (for the worst) over time and it seems like corrosion in a connector is a possible candidate for something that could cause a long-term downward trend/change in a sensor signal to the ECU.

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13 hours ago, TriumphTraitor said:

...

As many suggested, it was as the fast idle wax unit. I replaced it ($120 canadian pesos and a lot of cursing) only to find out that the one I replaced was still good

 

6 hours ago, triharder said:

...

(my wax unit is fine,  as the bi-metallic spring is not going to wear out within 46k and time doesn't wear out the effectiveness of  spring,  and I regularly flush my coolant lines)

...

I was recently having issues with my fast idle system - different than yours, but still issues. After pulling the fast idle unit apar, assuming that it needed replacing, I realized that the actual wax unit wasn't the issue: the fast idle valves on the throttle body itself were hanging up in the cold position. Not consistently, and not all of them, so the effect was intermittent. I cleaned the valves up by flushing them with MMO while actuating them by hand. Problem solved for me.

 

I would also agree with Greg's thoughts as a possibility... it's amazing how many weird VFR problems seem to come down to electrical connections in one way or another.

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