Engine misfires under load

[Keyzcat]

My 2005 just started misfiring,mostly under moderate acceleration,sometimes on startup. I can feather throrrle through it and all the power is back. No codes,t.p. is in specs and smooth,new plugs,new fuel w/ring free added. Kinda feels like a lean situation,I am an ASE certified AUTO mechanic so I've tried all the tricks that I would use for diagnosis on a car,but to no avail. This is the first problem I've had in 38,000 miles. Otherwise-flawless

Thanks for any info

 

[Bengt Weil]

I would suspect possible ignition high tension leakage - path of least resistance under load... Kinda tuff to test for without a dyno. Just a thought based on the age and the information given (perhaps plug wire failure during installation of new spark plugs?). Might be able to locate the cylinder by measuring the exhaust temp, looking for lower temp than the rest. Good luck!

 

[03HiYoSilver]

keyz,

In addition to what Beng stated, here is some other ideas:

Corroded Harness; https://www.fjrforum.com/forum//index.php?s...st&p=449902

Check for Kinked Lines under the tank

Since you stated you have New Plugs, there is a possiblity you distubed the wire(s) from the cap and/or may need to be reseated.

https://www.fjrforum.com/forum//index.php?s...83&hl=frank

Or it could be a TPS but they usually would code?

Hope this helps.

 

[ponyfool]

Is it happening in every gear, or just one? When I had my bent shift fork/gear dog issue, I first thought it was ignition misfire.

 

[Keyzcat]

Is it happening in every gear, or just one? When I had my bent shift fork/gear dog issue, I first thought it was ignition misfire.

No,happening in every gear. Definatly dropping 1 cyl. Took all advice and checked and cleaned ALL connectors,no real corrosion though. I had a code 30 in memory,coil for 1&4,but need to test it. I'm starting to lean that way. BTW,changed plug because of this problem first and am always very careful of ign. wires(tested those too)

Thanks for all the input. I'll keep ya posted

 

[Geezer]

Did you fill your gas tank shortly before this started?

 

[2WheelTiger]

Did you fill your gas tank shortly before this started?

That's exactly where I was gonna go. Is this possible compression detonation due to a seasonal change in fuels or a 'bad' gas station supply?

A quick and cheap test could be done by adding some octane booster to your fuel and seeing if the problem goes away. If not, they proceed to the more difficult solutions offered above.

 

[Geezer]

Did you fill your gas tank shortly before this started?

That's exactly where I was gonna go. Is this possible compression detonation due to a seasonal change in fuels or a 'bad' gas station supply?

A quick and cheap test could be done by adding some octane booster to your fuel and seeing if the problem goes away. If not, they proceed to the more difficult solutions offered above.

Well, I was thinking that maybe he just got some bad gas. It happened to me once. While I was trying to figure out what was wrong I used up the gas and filled up again. Problem went away.

 

[motorcycle-ed]

This happened to someone at EOM, turned out he had a failed Powercommander. Do you have one installed, if so, reconnect the stock plugs and try it.

Ed

 

[FJR1300KEN]

I would suspect possible ignition high tension leakage - path of least resistance under load... Kinda tuff to test for without a dyno. Just a thought based on the age and the information given (perhaps plug wire failure during installation of new spark plugs?). Might be able to locate the cylinder by measuring the exhaust temp, looking for lower temp than the rest. Good luck!

This is exactly where I'd be heading. Sounds like a plug wire breaking down under load. Make sure you use dielectric(pure silicone) grease on all connections including coil electrical. :clapping: Good luck!!

 

[madmike2]

One of the bikes at NAFO had the same problem. IIRC, it was Duff... It ended up being water in the gas that had settled in the injector for that one cylinder.

Just a thought. You might PM Duff and ask him if it was him and if that was the solution.

Let's hope it's something simple to repair.

 

[Keyzcat]

One of the bikes at NAFO had the same problem. IIRC, it was Duff... It ended up being water in the gas that had settled in the injector for that one cylinder.
Just a thought. You might PM Duff and ask him if it was him and if that was the solution.

Let's hope it's something simple to repair.

I greatly appreciate all of the responses,at first I thought bad gas,but after 2 tanks I shifted my thoughts. I have now pulled the tank off and will drain the gas to see if any water is occupying the fuels space

Again,thanks for the feedback

 

[madmike2]

I greatly appreciate all of the responses,at first I thought bad gas,but after 2 tanks I shifted my thoughts. I have now pulled the tank off and will drain the gas to see if any water is occupying the fuels spaceAgain,thanks for the feedback

It wasn't just bad gas, but something he'd fought for miles. As I said, evident'y the water had pooled and fouled one injector nozzle,

He was parked next to me but I was involved in many other activities and don't remember the entire story. That's why I posted to PM Gary and ask him. I don't remember if he had to pull the injector and blow it out or what other solution he came up with. I DO know that it was running on all four cylinders for his trip home from Golden, CO to the L.A. basin.

 

[Keyzcat]

I greatly appreciate all of the responses,at first I thought bad gas,but after 2 tanks I shifted my thoughts. I have now pulled the tank off and will drain the gas to see if any water is occupying the fuels spaceAgain,thanks for the feedback

It wasn't just bad gas, but something he'd fought for miles. As I said, evident'y the water had pooled and fouled one injector nozzle,

He was parked next to me but I was involved in many other activities and don't remember the entire story. That's why I posted to PM Gary and ask him. I don't remember if he had to pull the injector and blow it out or what other solution he came up with. I DO know that it was running on all four cylinders for his trip home from Golden, CO to the L.A. basin.

Just emptied the tank only to find-RUST. And too much of it. Rusting right at the lowest part of the tank by the fuel pump. I can't believe these things don't at least have a sock filter on the pumps,let alone a fuel filter. So now I'm looking for a new tank.

 

[Geezer]

Just emptied the tank only to find-RUST. And too much of it. Rusting right at the lowest part of the tank by the fuel pump. I can't believe these things don't at least have a sock filter on the pumps,let alone a fuel filter. So now I'm looking for a new tank.

Sorry to hear this.

I always figured that the 10% alcohol in our fuel would be sufficient to absorb any normal amount of water that gets in the tank. You must have gotten a pretty good gulp of water from a gas station or something to get enough in there to rust the tank.

The tank can be saved unless the rust has eaten through far enough to weaken it.