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WouldsAssassin

2011 YZ450F Sputtering

15 posts in this topic

Gents,

 

My '11 YZ has started sputtering at certain times and power settings. It seems to have a pretty consistant low RPM misfire as I slowly roll on the throttle. I've found it will also sputter, sometimes quite badly, when cruising the dirt roads between trails. I've gotten good at replicating the studder my slowly rolling on power, backing off slightly, then slowly rolling on again. When on the trail I don't notice the low RPM studder so much as it actually makes the power delivery a little smoother, but has screwed me when approaching obstacles. When I get the low RPM stumble usually a good whack of power and it pulls really hard to the upper revs. The cruising stumble, is pretty much a big loss of power. doesn't stall, but wont accellerate at all.

 

What I've done:

 

It seemed like fuel starvation, so I replaced the fuel pump and filter and had the injector serviced. No changes, still does it

 

Replaced the air filter and spark plug. No changes, still does it. 

 

Years ago I wired in some lights. I thought they could be affecting the electrical system and ignition. Removed it all and cleaned all the electrical plugs and connections I could find. No change, still does it.

 

Valves are in spec

 

Fresh oil and filters

 

It still starts how it always did, really well when cold and really inconsistantly when hot.

 

I'm at the point where I think I need to replace ignition components. I just don't know where to start.

 

ECU, injector, ignition coil, condensor, rectifier, plug wire? 

Edited by WouldsAssassin

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I am not a FI dude at all, but have you pulled the injector to ensure it's clean and that the fuel pump is alive and well? Your description does sound like a fuel problem to me.

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What I've done:

 

It seemed like fuel starvation, so I replaced the fuel pump and filter and had the injector serviced. Replaced the air filter and spark plug. No changes, still does it. 

 

Years ago I wired in some lights. I thought they could be affecting the electrical system and ignition. Removed it all and cleaned all the electrical plugs and connections I could find. No change, still does it.

 

Valves are in spec

 

Fresh oil and filters

 

It still starts how it always did, really well when cold and really inconsistantly when hot.

 

 

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Pull the stator cover and look for ferrous debris stuck to the pick up.

 

Pull the stator harness plug apart and look for corrosion.

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Derp, sorry - I don't read so good I guess. It still sounds like a fuel issue somehow, hope you figure it out.

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Stator pickup is clean. In fact the whole area looks like new. I guess it should with just 175 hours.

I'll check the stator connection tonight or this weekend.

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I would also test your TPS calibration, and harness connection.

 

You need to test the TPS in several throttle positions to see if the Carbon wiper is damaged.

 

An open or short would indicate this. 

Edited by KRANNIE

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A TPS fault will also show up as a trouble code.  With any system like this, you should pull codes first.  Doesn't always lead straight to the problem, but it can help.

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About to go out and check the stator output and the other connections I didn't check in the initial cleanup.

No trouble codes reported on the PowerTuner. I haven't done a TPS resistance check, but did note the position % on the tuner and with my calibrated eyeball gauge there weren't any noticeable changes, jumps or lags when opening or closing or holding the throttle at various positions as I would when riding. I'll hook up my multimeter to it after I do another plug check.

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162 hours on the meter. No faults unless 0 is an error code. 

 

I pulled the stator and regulator/rectifier plugs and was found quite a bit of dirt in the reg/rec plugs. Cleaned them and put it all back together. It started right up like always, but I was lacking the sobriety to take a test ride in my neghborhood. 

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162 hours on the meter. No faults unless 0 is an error code. 

 

I pulled the stator and regulator/rectifier plugs and was found quite a bit of dirt in the reg/rec plugs. Cleaned them and put it all back together. It started right up like always, but I was lacking the sobriety to take a test ride in my neghborhood. 

 

Pfffttt....

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Pfffttt....

Yeah yeah, just trying to be neighborly.

I got called out of town for work, won't get a chance to test it again until Wednesday.

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I finally got to test the latest round of repairs and I think that one dirty plug coming off the reg/rec may have been it.

Thanks Krannie for the advice.

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I have been having almost the exact sane problem w/ my '11. No error codes either. I am going to check my regulator/rectifier tonight.

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