2019 yz250f Back firing

NextGen
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9/5/2018 5:45am Edited Date/Time 11/21/2020 12:06am
I was wondering if it was normal that my 2019 yz250f back fires if you go from wide open throttle to engine braking and that it back fires same thing jumping. currently running the hard hitting map(Yamaha provides this tune stock) that is in the app also have the TP map load on map 2 they both make the bike back fire bike has 7hrs on it and as soon as I broke the motor in and went out for my first hard ride it started this back fire situation

also if I run t4 or renegade mx4 bike begins to back fire more under heavy riding
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Paw Paw 271
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9/5/2018 6:32am
Reset your TPS. It is set too lean from the factory.

Paw Paw
NextGen
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9/5/2018 8:17am
Reset your TPS. It is set too lean from the factory.

Paw Paw
im assuming it tells you how to do that in the Manuel?
NextGen
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9/5/2018 8:19am
is it a real loud back fire?
with the race gas yes but when im just running pump just like a decel pop not to loud

The Shop

kb228
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9/5/2018 8:23am
Tps needs adjusted. Youll have to hook up a volt ohm meter to it to do that. I
NextGen
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9/5/2018 10:04am
kb228 wrote:
Tps needs adjusted. Youll have to hook up a volt ohm meter to it to do that. I
what should the reading be ??
Paw Paw 271
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9/5/2018 11:25am
Most OEM TPS settings are about .5v, but most find improvement at a setting of .58-.62 v.
You will to make or purchase a wiring harness for this adjustment. ( and no, this adjustment is not in the owners manual)

Paw Paw
moto671z
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9/5/2018 4:29pm
My 19 yz250f also has a slight popping note in the exhaust when the throttle is chopped and on decel. My bike had crate damage to the mid pipe and the dealer replaced the it with a new one so I thought maybe they didn’t replace the gaskets or damaged one during the install. I am also interested in the procedure for adjusting the TPS voltage. The manual refers to a Yamaha diagnostic tool and adjusting to a specific code reading. See manual section 7-9. How are you guys measuring the TPS without the diagnostic tool?
Paw Paw 271
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9/5/2018 4:39pm
Do a search on line for TPS test wiring for your bike. If you don't find one then you may have to make one or get the dealer to reset it for you. There are many good videos on Youtube about this.

Paw Paw
NextGen
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9/6/2018 5:05am
moto671z wrote:
My 19 yz250f also has a slight popping note in the exhaust when the throttle is chopped and on decel. My bike had crate damage to...
My 19 yz250f also has a slight popping note in the exhaust when the throttle is chopped and on decel. My bike had crate damage to the mid pipe and the dealer replaced the it with a new one so I thought maybe they didn’t replace the gaskets or damaged one during the install. I am also interested in the procedure for adjusting the TPS voltage. The manual refers to a Yamaha diagnostic tool and adjusting to a specific code reading. See manual section 7-9. How are you guys measuring the TPS without the diagnostic tool?
im starting to wonder if this is a normal thing for the new 19 motor... because so far everyone that ive spoken with have the same sort of thing happening... the dealer where I bout it says to me its because of the stock muffler its cause a decal pop...
kb228
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9/6/2018 6:01am
The diag tool plugs into the ecu and displays all of the sensor information.

For my bike i made a “T” shaped harness that i could plug in between the harness for the TPS. Kawasaki had detailed schematics on where to put each wire. Then i used my multimeter to read and set the voltage. I would think you can do this on your bike. Might just take some guess and check work to get the voltage reading if Yamaha doesnt have schematics in the service manual.
kb228
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Heres a sketch of what i made.
moto671z
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9/8/2018 6:24pm Edited Date/Time 9/8/2018 6:25pm
Do a search on line for TPS test wiring for your bike. If you don't find one then you may have to make one or get...
Do a search on line for TPS test wiring for your bike. If you don't find one then you may have to make one or get the dealer to reset it for you. There are many good videos on Youtube about this.

Paw Paw
Thanks, I ended up ordering test wiring from TPS Tool. I turns out the 19 uses model 1. I did some research and saw that people are having luck with increasing the voltage into the .61 - .65 range but that was for KTM's. Is that voltage range also applicable for this bike?
moto671z
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9/10/2018 3:37pm
kb228 wrote:
Heres a sketch of what i made.[img]https://p.vitalmx.com/photos/forums/2018/09/06/285528/s1200_A2099030_489C_4172_83A8_CC89BE6508A0.jpg[/img]
Heres a sketch of what i made.
Stock voltage was set at .48. I bumped it up to .52 for now and will try it out when it stops raining. Anyone have an idea what the voltage should be for this bike?
tobz
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11/16/2020 1:45pm
kb228 wrote:
Heres a sketch of what i made.[img]https://p.vitalmx.com/photos/forums/2018/09/06/285528/s1200_A2099030_489C_4172_83A8_CC89BE6508A0.jpg[/img]
Heres a sketch of what i made.
moto671z wrote:
Stock voltage was set at .48. I bumped it up to .52 for now and will try it out when it stops raining. Anyone have an...
Stock voltage was set at .48. I bumped it up to .52 for now and will try it out when it stops raining. Anyone have an idea what the voltage should be for this bike?
Found this thread through google as my 2020 WR250f is popping on decel.

What was the outcome of this?

Thanks!
Paw Paw
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11/16/2020 3:12pm
The TPS setting should be between .5 volt and .62 volt as completely closed throttle. ( It will not idle with the throttle closed.) I would not go higher than about .65 volt.
Then check your WOT TPS reading. In theory it should be 5 volts at WOT, but most will not get that high right from the dealer. Then check the voltage change from closed to WOT and make sure the change is smooth through the stroke. If reading wanders or jerks as the throttle is opened the TPS is faulty.
Remember that the TPS tells the computer how to adjust the fuel delivery either more or less fuel based on the throttle opening. A pop in the exhaust on deceleration indicates a lean. The TPS adjustment can help solve this.

Paw Paw

Paw Paw
tobz
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11/17/2020 1:43am
Paw Paw wrote:
The TPS setting should be between .5 volt and .62 volt as completely closed throttle. ( It will not idle with the throttle closed.) I would...
The TPS setting should be between .5 volt and .62 volt as completely closed throttle. ( It will not idle with the throttle closed.) I would not go higher than about .65 volt.
Then check your WOT TPS reading. In theory it should be 5 volts at WOT, but most will not get that high right from the dealer. Then check the voltage change from closed to WOT and make sure the change is smooth through the stroke. If reading wanders or jerks as the throttle is opened the TPS is faulty.
Remember that the TPS tells the computer how to adjust the fuel delivery either more or less fuel based on the throttle opening. A pop in the exhaust on deceleration indicates a lean. The TPS adjustment can help solve this.

Paw Paw

Paw Paw
Following the manual, it appears to be in range, but not in the values that you’ve given. The pic shows 5v, and the manual says it should read between 4 and 6 volts. I just need to get a torx bit to adjust it to read slightly higher and hopefully should get rid of the popping in decel.

Fwiw the voltage doesn’t change when I open and close the throttle.



tobz
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11/17/2020 1:50am


Paw Paw
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11/17/2020 4:48am
Your voltage must change or it is not functioning correctly, if connected correctly.

Paw Paw
tobz
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11/20/2020 2:43am
Paw Paw wrote:
Your voltage must change or it is not functioning correctly, if connected correctly.

Paw Paw
Thanks, turns out that’s just the v5 that the tps uses, I moved the probes to the Yellow and black/blue wire and found these results, throttle at closed position shows this:




And then at wide open throttle:




Looks as though the voltage drops, is this something with the newer models? Would I then what the voltage to drop a bit lower to make it richer?
Paw Paw 271
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11/20/2020 4:55am
The voltage increases when working and set correctly. That is the industry standard for the TPS operation.

Paw Paw
tobz
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11/20/2020 12:28pm
The voltage increases when working and set correctly. That is the industry standard for the TPS operation.

Paw Paw
Ah right. So I still have the meter hooked up to the wrong wires? Sad
moto551
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11/20/2020 2:19pm
Try turning your idel down. I was adjusting my sons 2020 yz250f idea higher and he was having backfire issues. Turned down problem solved.

tobz
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11/21/2020 12:06am
Alrighty. For anyone else reading this, you slip the probes into the wires at each end of the connector. A probe doesn’t go into the middle wire.

From there you can read the tps input. Mine was .48v, shifted it to .58 then it moved to .60 when tightening.
I expect it to be a bit too rich but I’d like to see if it removes the popping on decel then maybe adjust it back until it begins to pop again, then I’ll know where the happy place is.

Thanks for your help PawPaw

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