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Discussion Starter · #1 ·
I recently had an issue with my bike having a dead miss (one of the cylinders wasn't firing). I replaced all the spark plugs and it rode fine for a couple hundred miles (only thing was the idle jumped around a bit) but yesterday I took it up to the mountains, it did fine, but on the way back it felt and sounded like it had the same problem as before. When taking off from a stop is when I really noticed it, once up to speed to seemed to be acting normal (we were doin 90mph+ trying to outrun a storm... no problem with the bike)

It didn't always do it though, sometimes it felt OK. I just got back from a short ride to see how it would do and it did fine too. Whats going on here?

Also, I wanted to run some injector cleaner through it (don't know if this could be the problem but it couldn't hurt, right?) and was wondering can I use the same stuff for a car or do I need something for a motorcycle specifically? Any recommendations?

The bike running normally:
http://www.youtube.com/watch?v=erlXH-tUMqY

The bike when it had a dead miss (and how it sometimes sounds/acts now):
http://www.youtube.com/watch?v=3-gMeFeO8iM

The bike & idle after I replaced the spark plugs (after the video above):
http://www.youtube.com/watch?v=EVPKAELs4pY

Thanks!
 

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you look at your coils at all when you had them off? any of them look like they had a whole or any burn marks on them? also you idol is a little low turn it up to about 1300. from the sound of the video it all sounds good. my bike has a rough idol as well but i havent had the time to sync my throttle bodies.
 

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I recently had an issue with my bike having a dead miss (one of the cylinders wasn't firing). I replaced all the spark plugs and it rode fine for a couple hundred miles (only thing was the idle jumped around a bit) but yesterday I took it up to the mountains, it did fine, but on the way back it felt and sounded like it had the same problem as before. When taking off from a stop is when I really noticed it, once up to speed to seemed to be acting normal (we were doin 90mph+ trying to outrun a storm... no problem with the bike)

It didn't always do it though, sometimes it felt OK. I just got back from a short ride to see how it would do and it did fine too. Whats going on here?

Also, I wanted to run some injector cleaner through it (don't know if this could be the problem but it couldn't hurt, right?) and was wondering can I use the same stuff for a car or do I need something for a motorcycle specifically? Any recommendations?

Thanks!

Just got back from a 2 hour ride this evening in the mountains trying to diagnose this same exact problem. It originally started during a trackday some months ago, and like many others I replaced my plugs/coils thinking that would solve it, but it hasn't done much. If anything the problem has gotten worse and more easily reproduced. It didn't hurt I had the bike dyno'd and the guy said he noted a high speed misfire. The plugs were indeed shot, and one of the coils didn't meet specs...but I had a lingering feeling it wouldn't totally resolve it.

The bike seems to surge a lot coming off fully closed throttle after I've run it on the freeway for a large portion of time. If the bike is turned off and allowed to sit, it runs normally the next time you go to start it. Sometimes it'll fall on it's face and not idle, and sometimes it will do just fine even after a trip of the same distance.

As I figure it, the ECU initially is running in an open loop system where it sets the fuel to WOT for warming. Once it's passed that phase, it starts the closed loop phase where it adjusts for atmosphere/runs the usual map. By the time that happens the ECU is paying closer attention to incoming air levels and the effects it has on engine delivery. Hence slight throttle changes from fully closed are harder to adjust for than ones when you're closer to WOT.

When my PC3 is hooked up the problems show up almost immediately and very pronounced, but when I unhook it it isn't as bad. The only thing I can figure is when the PC3 is hooked up the ECU has a harder time compensating for whatever it is causing the hiccup, so it takes it a moment to fight past what the PC3 is giving it. Either that, or the PC3 processes the incoming signals slower than the ECU does. Also I notice the bike runs rougher as the temperatures rise (more vibration from the engine at a given RPM).

I must clarify I'm no motorcycle mechanic...I've done a lot of car work and I fix computers for a living, but this is pretty out of my scope. Judging from what I've diagnosed so far, this seems to be on the right track.

If you don't already have the service manual from this site, you'll need to grab it. The things I plan to check are as such:

1) check TPS and verify it's within spec (doesn't bounce around on the meter) as well as check it's adjustment.
2) run the check on the air induction valve that's above the spark plugs as well as inspect and verify the connections of all vacuum hoses
3) check that the slides in the throttle bodies are smoothly opening/closing.
4) verify the synchronization of the throttle bodies.

It's interesting what hullbrose said about the idle...i've noticed my bike is idling a lot lower than it used to as well...usually was close to the half mark above 1k, but lately it's been 1k dead on. I think that may have something to do with this issue.
 

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Discussion Starter · #5 ·
Hey thanks for the input... like you, I'm no bike mechanic either and I think you're already over my head. My bike stock though, I don't have a Power Commander or anything like that. My bike also has never stalled out, it just don't have the power, and I haven't put together any pattern, it seems to just be random.

I actually broke my leg a few weeks ago, so my bike has been sitting in the garage as is :weeping ...I haven't had to ability to check on anything really as I have a hard enough time walking right now. I'm probably going to just take it in somewhere and see what they have to say about it, so hopefully when I'm able to ride she'll be good to go, but did that other thread solve your problem (I just skimmed it quickly)??
 

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Discussion Starter · #6 ·
Hey, skimming the other post I see its something about the ECU and error codes with the TPS, right? Well I have never seen my check engine light come on (other than when it is supposed to when all the lights come on when first turning the bike on). I'm going to check to see if any codes have been stored though. Also, is there any way to test an ignition coil? When I replaced my plugs they all looked normal... but I guess I didn't inspect them too closely, but I was wondering if the dealer could test them or something.
 

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Interesting update

I know what you're saying about the engine light...I haven't had one at all either.

So, I finally got done doing the throttle body sync this morning and the issue was still there (all 4 cylinders were out of whack, mostly #1 which was much further off than the rest). Letting it sit to run and warm up, it started messing up pretty bad. Checked the TPS yesterday, and it checked out fine. Along with that I discovered my idle speed screw was turned all the way out, so I put that back and got some idle back. When I sync'd the TBs it helped to explain my idle problems as well considering what shape things were in.

Pulled the coils, checked them to spec...all coils checked out. Plugs I didn't look at, but something my roomie came up with was asking if my battery was good. I hadn't thought to check it (duh, complicated fixes ftw right?!). So, we throw it on the meter and it's giving all of 10 volts. 6 on startup. Bad. tried starting it around 3/4 times in a row and it gave out completely.

Mind you, I had been running the bike for approx. 30 mins before that trying to get it to heat up/tune all 4 TBs. So, it should've ben charged right?

Check your battery, and if that checks out then take a look at the regulator rectifier. I've picked up a new battery but my test ride will be tomorrow/later this evening. If it turns out that fixed it I"ll be sure to let you know.
 

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Discussion Starter · #8 ·
I finally broke down and just dropped my bike off at a shop 30 mins ago. I just don't have the time or I guess enough knowledge, and I'd rather spend my time riding, and riding on a bike that I know isn't going to start acting up as soon as I get to the mountains. I'll be sure and let you know what they have to say about it. Did your battery help with your situation at all?
 

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turns out it was the battery 100%. Ra around with it on another hour long canyon jaunt and it pulls great, no idle issues, and it doesn't cut out even with the PC3. I did an additional sync this morning to clear up a small bit of hesitation I was getting and fixed the TB sync. Bike idled even better after that.

The TB sync smoothed the bike out a LOT but the issue we were discussing is gone entirely since replacing the battery, and in thinking aboutnit I don't feel it could be a rectifier. I'm hitting willow springs tomorrow so if it comes back that'll be the day to know for sure. Good luck at the shop!! I hope they can suss it out for ya. It's indeed frustrating :(
 
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