TPS Problems on 03 WR450
Posted March 05, 2005 - 07:31 PM
Performed the manuals testing and all voltages were good. It must be a CDI issue, but was wondering if this had happened to anyone else?
Also, does it hurt to run without the Throttle Position Sensor?
Thanks in advance
Posted March 05, 2005 - 07:37 PM
Posted March 05, 2005 - 07:45 PM
Posted March 06, 2005 - 04:04 AM
Unplugging the TPS should be in the Jetting troubleshooting guide as it will save some people from the jetting fire drill routine. One benefit from this experience is, I am getting good at removing a WR/YZ carburetor.
Posted March 07, 2005 - 07:31 AM
Posted March 09, 2005 - 11:22 PM
When rejetting, did you try going to a richer needle (not just change clip position)? On my 03 I first tried just going to richer PJs and this helped quite a bit but did not completely eliminate the stutter. I kept stepping up the PJ until it was obviously too rich but the stutter remained. I finally tried replacing the stock needle (Yamaha #OBDUT) with one a few steps richer (#OBDUQ) and the problem disappeared completely! I then reduced the PJ back to a #48 to clean up the richness at idle. The motor now E-starts easily hot or cold, accelerates smoothly right off idle and runs like the proverbial striped-ass ape.
Tried all combinations of jetting
You might give it a try before replacing the ignition module.............
Posted March 17, 2005 - 07:22 AM
I first worked on jetting. I tried every needle setting and even another leaner needle. The bike stutter acted rich and sent me on a long runaround, although I learned a lot. I believed what Vortex told me about the spark plug voltage dropping, because I had a 250WR act rich when the battery was dischaged with the head lights turned on. (It had a Baja design kit and I did not change out the high wattage stock bulb for the low wattage bulb Baja suggested. So it wasn't a Baja problem.)
The Vortex ignition is a CDI unit that replaces the stock CDI.
The stutter at 1/4 throttle occurs when you try to ride at a constant rpm. I noticed as I got use to the bike the problem is not as pronounced on the stock map because I give it more gas. The YZ seems to want lots of throttle or off, not in between. It was hard to show the dealer this problem because the young guys there ride on and off. When I used a constant throttle, they were surprised at the stutter. After calling Yahama, etc. they said they could not fix it and thats when I looked into either replacing the TPS or going with the Vortex.
I went with the Vortex because it has 10 different maps from traction to performance including the stock map. The traction maps did not have the stutter while a few of the performance maps did. Again, I guess a racer does not sit at 1/4 throttle. It was very enlightening how the CDI can cause one to think they have a jetting hole.
I still wonder why the CDI can't just throw all 12V to the plug all the time rather than varying. I guess it is a software bug when the unit drops the voltage to <1V and causes the stutter.
Posted March 17, 2005 - 06:07 PM
Posted March 21, 2005 - 04:16 PM
To sum it up, I think that a racer or perfectionist will notice the map changes dramatically. A newbie or person who just likes to ride easy, for fun, small 2 ft jumps (i.e. old man like me) will find the map differences not that big a deal. (But then set the map on the highest performance.)