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-   -   Coming Off Throttle, Bike Stalls? (https://www.zx6r.com/zx6r/59332-coming-off-throttle-bike-stalls.html)

TheSloMoShow 08-26-2014 11:10 AM

Coming Off Throttle, Bike Stalls?
 
Hello everyone,

I've just recently rebuilt my bike and had a hell of a great time getting to ride it around the past few weekends but I keep running into a problem every now and then.

It first happened the day put it back together...when I shifted down into first to go around a tight corner I had let off the throttle. I was just getting ready to get back on the throttle when the bike suddenly stalled. Electronics still worked fine, no error codes. But I watched the RPMs literally die down to zero.

I started her back up and took off, didn't happen again for a few days. The second time it happened, I adjusted the idle (raised it to 1.5k) and everything was kosher for a good week or so.

Then just the other day, I was on a country road and needed to fix something on my left glove. So I pulled over and coasted in 4th with the clutch pulled in at about 50 mph and quickly fixed my glove. Before I could get back on the throttle, it stalled again. I still had the clutch pulled in, so I came to a complete stop and started it back up and took off. It happened once more later that day, coming to a stop light in first gear.

Its been a few days since the last occurrence, and it doesn't happen all that often but ot does worry me. I just adjusted the valves, replaced plugs, ran a compression test and cleaned the TBs. (Didn't do a TB sync, but I would think my bike would have idling problems ALL the time if this was the problem)

My first thought was maybe, in putting the TBs back on the head, I somehow forced the butterfly's close. But it idles fine, it only stalls when letting off throttle and coming to a stop?

Anyone else experienced this?

Iantee 08-26-2014 02:17 PM

I had the same thing happen to me about a year ago. It would happen about 2x a day

I would be slowing down to a stoplight and right when I shifted down the power would just die.

But my problem was fixed when I just adjusting the idle speed to 2k. So I'm wondering since you tried that, what else it could be

Steel 08-26-2014 02:43 PM

Quote:

Originally Posted by TheSloMoShow (Post 950607)
Hello everyone,

I've just recently rebuilt my bike and had a hell of a great time getting to ride it around the past few weekends but I keep running into a problem every now and then.

It first happened the day put it back together...when I shifted down into first to go around a tight corner I had let off the throttle. I was just getting ready to get back on the throttle when the bike suddenly stalled. Electronics still worked fine, no error codes. But I watched the RPMs literally die down to zero.

I started her back up and took off, didn't happen again for a few days. The second time it happened, I adjusted the idle (raised it to 1.5k) and everything was kosher for a good week or so.

Then just the other day, I was on a country road and needed to fix something on my left glove. So I pulled over and coasted in 4th with the clutch pulled in at about 50 mph and quickly fixed my glove. Before I could get back on the throttle, it stalled again. I still had the clutch pulled in, so I came to a complete stop and started it back up and took off. It happened once more later that day, coming to a stop light in first gear.

Its been a few days since the last occurrence, and it doesn't happen all that often but ot does worry me. I just adjusted the valves, replaced plugs, ran a compression test and cleaned the TBs. (Didn't do a TB sync, but I would think my bike would have idling problems ALL the time if this was the problem)

My first thought was maybe, in putting the TBs back on the head, I somehow forced the butterfly's close. But it idles fine, it only stalls when letting off throttle and coming to a stop?

Anyone else experienced this?

Two quick questions before I go into something detailed (I'm lazy at the moment).

How long have you had the bike?
How many times have you made valve adjustments before?

oKayH 08-26-2014 02:54 PM

Could be a TB sync issue.

Bennett636 08-26-2014 03:12 PM

Quote:

Originally Posted by oKayH (Post 950728)
Could be a TB sync issue.


Was about to say the same thing

TheSloMoShow 08-26-2014 06:11 PM

Quote:

Originally Posted by Steel (Post 950724)
Two quick questions before I go into something detailed (I'm lazy at the moment).

How long have you had the bike?
How many times have you made valve adjustments before?

I've had the bike since mid June.

I've only ever made valve adjustments to my R1(once). Since I just got this Zx6R in June, this is obviously the first valve adjustment I've done on it.

TheSloMoShow 08-26-2014 06:14 PM

Quote:

Originally Posted by Bennett636 (Post 950732)
Was about to say the same thing

That's my first guess...seems odd that this only happens when coming off the throttle completely and it doesn't occur every time either.

Something else that might be worth mentioning--- the female end of my cam position sensor has been somewhat crushed. It still fits on the male end just fine, but I had to use rtv silicone to seal the outside together. No FI lights or error codes have ever popped up.

TheSloMoShow 08-26-2014 06:16 PM

Quote:

Originally Posted by Iantee (Post 950719)
I had the same thing happen to me about a year ago. It would happen about 2x a day

I would be slowing down to a stoplight and right when I shifted down the power would just die.

But my problem was fixed when I just adjusting the idle speed to 2k. So I'm wondering since you tried that, what else it could be

I've never had it above 2k---my thought was that if my bike has to idle at that speed, then there is something much bigger I need to worry about.

I.e., I prob should have multi-quoted these last 3 responses lol.

Texas636 08-26-2014 07:11 PM

Have a Power Commander or a Bazzaz, Tune, etc...?

TheSloMoShow 08-27-2014 03:45 AM

Quote:

Originally Posted by Texas636 (Post 950833)
Have a Power Commander or a Bazzaz, Tune, etc...?

Negative. All stock fuel map.

Hilters Cat 08-27-2014 04:06 AM


RJ2112 08-27-2014 05:41 AM

Also, look at the inside of your fuel tank and see whether it is free of rust..... you could be clogging your fuel delivery at some point. What does your filter look like?

Steel 08-27-2014 04:25 PM

Ugh, this isn't ever an easy thing to diagnose. The issue that you're having is a secondary effect, and it could be caused by about a dozen things.

But before I start giving you things to go check, here is what I believe is happening. The main symptom of the problem is a poor air/fuel ratio at lower rpm (and possible throughout the whole range). It isn't necessarily going to be bad enough to notice while idling without moving, but, as you are riding and let off the throttle, the rapid air pressure change in the intake box makes the air/fuel ratio go so far from ideal that it doesn't make enough power to keep the engine running. By increasing your idle speed, it just means that when you let off the throttle again while moving, the engine still generates enough power to continue running; however, there isn't correcting the main problem, just treating the apparent symptoms.

Anyhow. As already said a few times, you should check that your throttle bodies are sync'd.
Beyond that, I'd force the subthrottle to stay open and make sure that isn't an issue. Check that your inlet air temp sensor is reading properly, IIRC it is an RTD so you'll just need an ohm meter and another temp probe that you trust. Same thing with the inlet air pressure and atmospheric pressure sensors.
And then....fuel pressure could be bad, either because the pressure regulator, fuel filter, or the pump itself is having issues.

TheSloMoShow 08-27-2014 04:30 PM

Quote:

Originally Posted by Steel (Post 951207)
Ugh, this isn't ever an easy thing to diagnose. The issue that you're having is a secondary effect, and it could be caused by about a dozen things.

But before I start giving you things to go check, here is what I believe is happening. The main symptom of the problem is a poor air/fuel ratio at lower rpm (and possible throughout the whole range). It isn't necessarily going to be bad enough to notice while idling without moving, but, as you are riding and let off the throttle, the rapid air pressure change in the intake box makes the air/fuel ratio go so far from ideal that it doesn't make enough power to keep the engine running. By increasing your idle speed, it just means that when you let off the throttle again while moving, the engine still generates enough power to continue running; however, there isn't correcting the main problem, just treating the apparent symptoms.

Anyhow. As already said a few times, you should check that your throttle bodies are sync'd.
Beyond that, I'd force the subthrottle to stay open and make sure that isn't an issue. Check that your inlet air temp sensor is reading properly, IIRC it is an RTD so you'll just need an ohm meter and another temp probe that you trust. Same thing with the inlet air pressure and atmospheric pressure sensors.
And then....fuel pressure could be bad, either because the pressure regulator, fuel filter, or the pump itself is having issues.

I'll take a look at these this weekend-- hopefully one of these issues is the true culprit. Thanks again.

kingofthehil 08-28-2014 07:57 AM

Dont know if it helps, but my B2H was in the shop for 4 weeks trying to diagnose a problem where it stalled off throttle and wouldn't start again immediately. Sometimes did sometimes didn't.

After working through everything they found that the cable loom on the right hand side below the tank (and feeding the throttle position sensor) was shorting to the frame intermittently. Re-insulated - now runs perfectly!!


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