Engine shutdown at 3000 RPM / 80 mph - Road Star Warrior Forum : Yamaha Star Warrior Forums

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Old 05-25-2009, 11:45 AM   #1 (permalink)
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Default Engine shutdown at 3000 RPM / 80 mph

I wanted to run my troubleshooting process by you guys and see of this makes sense. First, a little background. A few days ago I started a bunch of mods to my 2007 midnight (already had Bigshots). Added Churckey VBAK, Coil & Sensor relocation, AIS block off, added a PC3 (used a map from the downloads section with my exact setup).


So I get finished and go out on the 10 mile test drive. At one point I was going about 80mph and slowing down slightly when the engine seemed to cutout for 1 or 2 seconds. It was so subtle that I wasn't even sure what happened, so I started thinking and remembered that in my excitement to go on the test drive I forgot I was supposed to zero out the throttle position on the PC3 (I think, that must be the problem). Went home, and did that, then went for a 50 mile ride. no more engine cutouts. The next day I went for another 100 mile ride and in the first 20 minutes the engine completely shutdown at right around 3000 rpm (80mph) about 8-10 times for anywhere from 2 to 6 seconds. I could recreate the same feeling by riding at 80mph and flipping the kill switch off, then flipping it back on, so I knwo the engine was completely shutdown and just restarting as soonas I got spark again. So now I've got a problem. I first checked all the work I did and everything looks good.Then I start searching on here for possible causes.


The search reveals, CPS, TPS, LAS (Lean Angle Sensor), as leading possiblities. My mods didn't really mess with any of these other than the fact that the PC3 is interacting with the TPS. I found a post that said that the LAS is located near the rearhorn, so I thought maybe I screwed it up with the bike jack somehow. I unplugged the LAS and when it came off the little black sheath around the wires poured out about a teaspoon of water. Those sheaths don't seal up at the connector, and mine was positioned with a loop in it so that it held water. I'm thinking that at 80 mph I got enough pressure or suction to move the water out of the loop and into the back of the LAS connector, which activated it. I blew the wires & connector with a hair dryer and went for a 30 mile ride. No problem. Went for another 50 mile today. No problem.


So it SEEMS like my problem was water pooled up near the LAS, but conventional problem-solving would suggest that if you change a whole bunch of stuff, and then immediately start having a problem, the problem is related to the changes. In my case the LAS and waterwas completely unrelated to the changes, so I'm having trouble convincing myself that my problem is actually gone. What do you think? Anybody have any other guesses on what this might be?


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Old 05-25-2009, 11:55 AM   #2 (permalink)
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Default Re: Engine shutdown at 3000 RPM / 80 mph

sounds like you found the problem I might put some dielectric grease in the connection to keep it from happening again but keep an eye on it and mabey check your plugs sure seems odd that it only happened after the mods.
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Old 05-25-2009, 11:56 AM   #3 (permalink)
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Default Re: Engine shutdown at 3000 RPM / 80 mph

Hey Jamie, I had similar issue: Riding at sustained 3000 rpm/80 mph, bike would cut out...and would be difficult to restart at times. I checked every connection and sensor that could cause the problem...I concluded that my LAS was bad (no water in it.). I went to my local Yammi dealer and the service guy replace it. No problems yet. Good luck, John
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Old 05-25-2009, 11:57 AM   #4 (permalink)
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Default Re: Engine shutdown at 3000 RPM / 80 mph

Nice detective work! Those are the toughest kind of problem, and yes... I would have been looking at the recent work too. Only time will tell.


You might check the trouble code history, you covered everything else.
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Old 05-25-2009, 02:29 PM   #5 (permalink)
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Default Re: Engine shutdown at 3000 RPM / 80 mph

i did my BAK, AIS, coil relocation and PC3 saturday. wired the coils wrong so it was firing 180 out. flames out of the pipes are cool. got that fixed, rode it and no problem. washed the bike yesterday, rode it, no problems. went to ride it today, got about 100ft from the house at very low rpm's and the bike shut down... like the battery was disconnected. no dispaly or lights. turned the key off and you could hear the fuel pump run for about 2 seconds. turned it back on, lights good, display good... fires right up. no problems since then. i'll have to check my LAS to see if there's water in the connector!!
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Old 05-25-2009, 03:22 PM   #6 (permalink)
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Default Re: Engine shutdown at 3000 RPM / 80 mph

Time will tell, but coincidences do happen which is why we have a word for them! I any event the symptoms match the LAS so hopefully you solved it (but you'll have to tell us if it comes back!).
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Old 05-28-2009, 10:20 PM   #7 (permalink)
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Default Re: Engine shutdown at 3000 RPM / 80 mph

Thought I'd provide an update on this. I've got 450+ miles on since I discovered the water in the sheath around the lean angle sensor. No problems, no shutdowns, cutouts, or error codes in the computer. And that's with a lot of 3000 rpm/80 mph riding.


So I'm calling this case closed. If you run into this problem this is an easy thing to check for, so maybe it will help somebody in the future.


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Old 07-14-2009, 03:03 PM   #8 (permalink)
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Default Re: Engine shutdown at 3000 RPM / 80 mph

would anyone by chance know what the part number for the LAS is? Do they have a tendency to go bad?

If it is cheap enough I might just buy a spare to keep handy....



credit to ohiostar11 for posting this a while back:

"The LAS is on the left side of the Bike directly behind theHorn. Two
10mm nuts for the horn, one 8mm bolt for the bracket to the LAS and two
hex screws to remove the switch housing. Un plugold switch,
di-electric grease and plug in a new switch and I am back in business,
so I beleive. More riding (testing) necessary until I am 1000%
confident it's fixed. Will post againtomorrow after some more riding
(testing)."

When I had similar symptoms I replaced my CPS and I have not had that problem ever since. The LAS replacement seems like an easier job than the CPS lol...
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