Author Topic: downtown 125 rough idle  (Read 739 times)

Hezi241

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downtown 125 rough idle
« on: July 31, 2016, 03:32:55 PM »
Hi,

After replacing piston and rings
Put all together and get fault codes
P1120
P1121 both related to throttle position sensor
Tried all reset prucedures of the dt 300 and nothing work
What should i do?

Thank you

CROSSBOLT

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Re: downtown 125 rough idle
« Reply #1 on: July 31, 2016, 07:06:58 PM »
Could be the TPS is turned out of range so initialize won't do the trick. I don't recall what resistance equivalents are but the volts are what the ECU sees. You could turn the TPS after you reset the ECU and clear the codes and see what happens. The reset procedure is similar to initialize except you hold the throttle open for 10 seconds instead of 8. The sequence should be: 1. reset ECU 2. Initialize 3. test for codes. Then, if you show codes: 1. reset ECU 2. turn TPS in one direction 3. initialize 4. test for codes. Then if you still have codes do the same thing over, moving the TPS in the same direction the same small amount as the first time and repeat the above sequence. Do this three times and if you still have the codes set the TPS back where you started and start over moving the TPS in the other direction until codes disappear. This is way easier with the Kymco analyzer tool but I am assuming you don't have one.

Karl
Karl

Three motorcycles 1960-1977 (restored a 1955 BSA)
Agility 50
Yager 200i
Downtown 300i
Navy tech, Ships Engineer, pilot and aircraft mechanic

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