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Need help from experienced diagnostic mechanics

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A little history, (KX 450F 2011)I have had coolant temp. sensors issues in the past. I found that problem using the wiggle method. I replace the sensor and the connector on the harness, all was good for about 50 hours of ride time.

Yesterday the bike shut off in the air and fired back up upon touch down. When it started back up it was acting like it was missing. I started wiggling every connector I could touch to see if I could pin point the problem but there was no change. I disconnected the coolant temp sensor while it was running and still no change.

I didn't have an ohm meter at the track with me so I decided to change the plug just to see if maybe I fouled one. I have never fouled a plug in one of the four stroke bikes so I don't know how they react.

After about 10 minuets I had the spar plug in and it ran normal. Just to check I put the old plug back in and it also ran normal. Now I am freaked out because I know I didn't find the problem.

I am guessing the amount of time it cooled off corrected the problem but now how do I find it? Should I buy one of the inexpensiveicon1.png trouble code reader kits and see if it points me in the rite direction? I know it should show a coolant temp. code because I disconnected it.

I rode the bike for about another hour and kept the wheelsicon1.png on the ground and it never acted up once so now I am really freaked out.

I'm going to put an ohm meter on a few of the sensors to see If anything shows it's face but I would also like to be able to check for codes.

Have you had any luck finding these type of gremlins?

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Your problem sounds like the same one my friend had on his KX450F. It turned out to be the tip over sensor.

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Your problem sounds like the same one my friend had on his KX450F. It turned out to be the tip over sensor.

Any idea how they pinpointed it? Did his run, just not well? I would think if that sensor failed it would not run or would not shut it off during extended tip overs.

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Sometimes a faulty ignition coil can cause problems when hot. As the temp rises the internal wiring can shift and disconnect if there is a break in the wiring somewhere. As the coil cools down the internals contract and reconnect the break in the wire. This type of problem can be very intermittent at first.

You can test the coil with an ohm meter both when cool and at operating temp. Also check the plug wire and plug boot to make sure all connections are solid.

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Any idea how they pinpointed it? Did his run, just not well? I would think if that sensor failed it would not run or would not shut it off during extended tip overs.

His would pop and quit in the air when jumping or right when he landed and hit the throttle. He had a Kawasaki tech look it over at a race and he said to try it. So far so good.

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Here is what I think I know so far... Kawi omitted the section where they tell you how to erase trouble codes. Without the ability to erase codes you never know if the code is current with the software they use.

They also state the ECU stores codes. I can't get mine to store a code unless it is currently in fault. My ECU didn't show any codes so I forced it to show a code by disconnecting the coolant temp. sensor. Code 14 showed up and as soon as I plugged the sensor back in the code went away. So basically if you have an intermittent open or short it will only show the code during that intermittent time.

With this design I need to force a hard fault, intermittently, then try to get the code out of it before it decides the intermittent time is up. Rite now I feel like I want to choke the brains behind this design... who knows maybe I need to choke myself for not knowing how to operate it.

What are your experiences with it so far and does the 600 dollar software help any better with diagnostics than just reading the noid light?

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I've seen these similar issues on yz's. when the bike gets hot it causes the stator to malfunction. The symptoms of a stator are similar to a fuel pump. The only way to check and see what is broken is to use a ohm meter and see what is out of spec. I rad your other post and it sounds like you replaced the pump already so it may be the stator.

I had a similar issue and changed out my temp sensor first but no go. I had a connect on a fuel pump so I tried that and it fixed the problem.

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I was in the same boat earlier this summer with my 09.....

http://www.thumperta.../#entry10684079

I do have a good stator and coil if you would like to rule those out.

Thanks a million for the offer, I may take you up on it. I read your thread and you hit the nail on the head with having a donor bike to test with.

I used to be a very experienced diagnostic tech. for Toyota and Chevrolet and the design of this DFI system drives me nuts. It is almost the bare essentials to eliminate the carb.

My major issue now is I can't replicate the problem and of course the ECU doesn't show any codes.

We went to a private practice track and I had 4 guys rotating through every 10 minuets for an hour while I stood waiting with all the diagnostic tools laid out and ready to go at a moments notice and we couldn't get it to act up. Basically until I can force the problem to show itself we are guessing and if I start throwing parts at it I won't know if we fixed it.

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