ECU cuts out

[dfrew]

I have an 08 KFX450R, and I will notice that at mid-high RPMs, it starts cutting out. I have to shut the quad completely off, and then turn it on and then try it again. Sometimes this takes 2-5 resets to get it to run right. I have a Power Commander III (brand new), a new wiring harness, K&N filter, and Two Brothers pipe. I've also adjusted the Throttle Position Sensor per Ron Wade's tips. Any thoughts?

[johnnyboy]

I would say it sounds fuel pump/filter related but there are much more qualified people on here to give you pointers but its what I would look at first

[AZkfx450rider]

is your tps wire damaged from tapping the pc3 up? also check all of your grounds, most of mine looked good but i went ahead and scuffed up the frame to ensure good contact anyways, did you dielectric grease ur connectors?

[dfrew]

I got a new wiring harness about 2 months ago (because the quad wouldn't even start...that was the problem), and I used dielectric grease for every connection. I adjusted the TPS per Ron Wade's instructions, and seemed to make it worse, so we set it back to the original position, but it's still doing it. I didn't know if it could be a Coil, Rectifier, O2 Sensor, TPS, or ECU. It definitely seems to be electrical because once it gets set right, it runs great. So the problem seems to be intermittent.

[Duster]

Quote: Originally Posted by dfrew

I got a new wiring harness about 2 months ago (because the quad wouldn't even start...that was the problem), and I used dielectric grease for every connection. I adjusted the TPS per Ron Wade's instructions, and seemed to make it worse, so we set it back to the original position, but it's still doing it. I didn't know if it could be a Coil, Rectifier, O2 Sensor, TPS, or ECU. It definitely seems to be electrical because once it gets set right, it runs great. So the problem seems to be intermittent.

The TPS is a rheostat... output voltage increases as it is rotated more.

What is does is tell the ECU how far the throttle butterfly is opened for fuel metering.

Increasing this voltage just makes the entire throttle range richer.
The ECU is metering more fuel to less actual air coming in.

Check the PC's wire tap on the TPS wire.

The coil and coil wire are easy to check per the manual.
While doing so, check the condition of your plug... as you might be rich.
Or your plug just might have been fouled some before you started this stuff.

Rectifier... not really so easy to check.
If you have proper voltage at the battery when at idle and revs, it's likely OK.

No o2 sensor to deal with.

[Dust Devil]

Quote: Originally Posted by dfrew

I have an 08 KFX450R, and I will notice that at mid-high RPMs, it starts cutting out. I have to shut the quad completely off, and then turn it on and then try it again. Sometimes this takes 2-5 resets to get it to run right. I have a Power Commander III (brand new), a new wiring harness, K&N filter, and Two Brothers pipe. I've also adjusted the Throttle Position Sensor per Ron Wade's tips. Any thoughts?

(DFI) self-diagnosis Chapter 3-33 (Service manual)

http://files.me.com/bauman43/tl8ntm

Does your FI light stay on???or flashes? when you turn your ignition on... (Which is next to your neutral light)

on your (Hood)... Also check your mapping on your power commander III? you might need a different map setting to adjust from...

http://www.powercommander.com/powerc...dl=143&yr=2008

Rectifier... not really so easy to check.
If you have proper voltage at the battery when at idle and revs, it's likely OK.

See manual (16-30 electrical system) about the Voltage regulator/rectifier and the resistance chart to test from...