Stuttering problem, I'm at a loss (Update, Problem Fixed)

My bike is a 2004 with 111,000 miles on her. Several months ago, she developed a stuttering problem. Afterward I -

changed plugs,

adjusted the valves,

ran Seafoam in the tank,

did a throttle body sync,

trimmed the ends of the spark plug wires that screw into the boot,

checked and cleaned (not really much) the corrosion inside the spark plug boot after pulling apart,

and last summer I cleaned and used dielectric grease on the large white plug under the thermostat ...

I am going to use a meter to test the coils and I am going to flush out my injectors.

I have a feeling that it could be the coil/wires for cylinders 1&4 because this weekend I pulled the plugs and 1,2,3 looked fine but 4 looked a little wet. I believe that they all are getting at least a weak spark because last night I had the bike running and pulled 1 injector at a time and each one I pulled, caused it to run more rough. Another reason that I am thinking coil 1&4 is because as it was getting darker out,(all I have to work in is a carport) I was letting her run at about 2500 RPM for a while and as I released the throttle, I noticed that the headers were glowing only on cylinders 2&3.

A little more info that is odd. When cold or cool, it stutters the most with about 80% power in the whole RPM range. At idle, the stutter is light with just a little bit of popping. The stutter is more evident while riding. Now the kicker, if she gets 3+bars temp especially on a nice warm day, the stuttering gets a little bit less and I have about 98% power. Yes, she is running better all hot and bothered.

Ideas? If I keep scratching my head like this, I am going to go bald! I don't really have much money to throw at it.

Carl

n2osx said:

A little more info that is odd. When cold or cool, it stutters the most with about 80% power in the whole RPM range. At idle, the stutter is light with just a little bit of popping. The stutter is more evident while riding. Now the kicker, if she gets 3+bars temp especially on a nice warm day, the stuttering gets a little bit less and I have about 98% power. Yes, she is running better all hot and bothered.

Click to expand...

You seem to be chasing electrical problems but the problem could also be fuel injection. It been a while since I looked at the how the fuel injection system determines fuel enrichment but I think the coolant temperature sensor is one of the data points. If you have a bad sensor telling the ECU that the engine is hot or cold when it actually is not then the fuel mixture may be off until the engine eventually gets "all hot and bothered" (this is not not my area of expertise so please fact check everything I said).

If the problem is the 1&4 coil you should be able to switch the coils and see if the problem shifts to the 2&3 cylinders.

As for your plug test, remember that the 1st and 2nd Gen FJRs use a wasted spark design. So when you unplug one spark plug wire, both plugs fired from that coil do not fire.

That is a good call that I will continue to look into as well. Thank you

Carl

You forgot to mention you broke shit.. Just thought I'd remind you

Hire a speech therapist for your bike.

Bustanut joker said:

You forgot to mention you broke shit.. Just thought I'd remind you

Hire a speech therapist for your bike.

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You probably gave my bike the Herp last time were out this way. There has been a constant ooz coming out of both mufflers ever sense the Reuben Run 2013! Leave my bike alone you Prick!

shot battery?

Spud said:

shot battery?

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New last summer and still extremely strong. Good call tho.

Carl

If it was mine I might do a compression test just for fun.

I did that last weekend. I believe they were 168, 180,183, 180. Just a touch of oil down the hole of #1 shot the reading way up. Not too bad for 111,000 miles.

Carl

Then I might take her out on some backroads and wring the shit out of her.

Show that bitch what hot and bothered really means.

If it doesn't kill her it will make her stronger.

Maybe....

rushes said:

Then I might take her out on some backroads and wring the shit out of her.Show that bitch what hot and bothered really means.

If it doesn't kill her it will make her stronger.

Maybe....

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LOL I have done that as well.

However, while sitting here at work with my thumb in my ass (unfortunately I have large thumbs!), I think that I figured it out. Last summer I installed a used Techlusion Fuel Controller. When I started having problems, I turned all the dials down to 1 or 0 and that is supposed to bring the bike back to bone stock fueling. I am going to go home and disconnect it altogether and I am guessing my problem may go away. I may just have a bad controller or maybe a wire is messed up or something. I hope that it's not altogether bad because I liked benefits that it gave the bike.

Carl

Rushes may have it. My opinion would be clogged Catalytic converter. You either need a replacement or a Catsectomy done on the old bitch.

Good luck,

Dave

08FJR4ME said:

Rushes may have it. My opinion would be clogged Catalytic converter. You either need a replacement or a Catsectomy done on the old bitch.

Good luck,

Dave

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A clogged cat (!) will cause power loss at higher RPM but not a rough engine and it will not change with engine temperature.

It is telling that the header temperatures are different with the two inside pipes appearing hotter. Could be fueling, could be spark. It is notable, as you noted, that cyls 1 & 4 don't glow the headers and are sparked by the same coil. Sometimes life likes to goof on ya and throw in what looks like a sure thing only to have something else quite less likely to be the real root cause.

I think it is a great idea to take the aftermarket fuel trim unit out of the picture before going on with other ideas.

As always, change just one thing at a time, measure/note/confirm any changes and then move on to the next item.

I assume that the engine was not completely up to operating temperature or perhaps the battery wasn't fully charged when the compression check was done.

n2osx said:

rushes said:

Then I might take her out on some backroads and wring the shit out of her.Show that bitch what hot and bothered really means.

If it doesn't kill her it will make her stronger.

Maybe....

Click to expand...

LOL I have done that as well.

However, while sitting here at work with my thumb in my ass (unfortunately I have large thumbs!), I think that I figured it out. Last summer I installed a used Techlusion Fuel Controller. When I started having problems, I turned all the dials down to 1 or 0 and that is supposed to bring the bike back to bone stock fueling. I am going to go home and disconnect it altogether and I am guessing my problem may go away. I may just have a bad controller or maybe a wire is messed up or something. I hope that it's not altogether bad because I liked benefits that it gave the bike.

Carl

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I think you have just nailed it. Of course you never revealed that you had such a thing connected or we'd have all jumped on it like BeemerDonS on a donkey's backside.

+1

Fred W said:

n2osx said:

rushes said:

Then I might take her out on some backroads and wring the shit out of her.Show that bitch what hot and bothered really means.

If it doesn't kill her it will make her stronger.

Maybe....

Click to expand...

LOL I have done that as well.

However, while sitting here at work with my thumb in my ass (unfortunately I have large thumbs!), I think that I figured it out. Last summer I installed a used Techlusion Fuel Controller. When I started having problems, I turned all the dials down to 1 or 0 and that is supposed to bring the bike back to bone stock fueling. I am going to go home and disconnect it altogether and I am guessing my problem may go away. I may just have a bad controller or maybe a wire is messed up or something. I hope that it's not altogether bad because I liked benefits that it gave the bike.

Carl

Click to expand...

I think you have just nailed it. Of course you never revealed that you had such a thing connected or we'd have all jumped on it like BeemerDonS on a donkey's backside.

Click to expand...

Hell, that's how I came to the thought. Just going over everything in my head and the controller popped into my head like a light bulb. If I thought of it earlier as I was writing the first post, I probably would have just deleted the whole thing till I tried that. LOL I will keep you guys updated on what I find after I check into that tonight.

Carl

Uhg..... I absolutely hate anything aftermarket added to already high performance machines....

They tend to muck things up more then they improve them....

What exactly is the reason for this device ?!?!

Warpdrv said:

Uhg..... I absolutely hate anything aftermarket added to already high performance machines.... They tend to muck things up more then they improve them....

What exactly is the reason for this device ?!?!

Click to expand...

Allows you to add fuel where you want in order to smooth out the running where Yamaha often leans out the fuel in stock form. Example being often cruising through city streets at about 35 mph, most of the time the stock Yamaha settings will give you a little bit of a surging sensation due to being a touch too lean. You can set this box to richen it up where you need it.

Carl