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Old 09-12-2010, 03:10 PM   #1
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Questions?? Nitro Engine moves forward on idle

I have a TMAXX 2.5 and for some reason the truck is moving forward at idle. Its probrably a simple fix but it is accelerating once I turn on the radio and receiver. The brakes is also not responding well. The car was running fine yesterday. Anyone knows what could be causing this issue. I have messed with the carb running it lean and rich but seems to accelerate still. Someone Help!
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Old 09-12-2010, 03:17 PM   #2
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Default Clutch

Probably your clutch bearings are out or some part of the clutch binding and causing it to engage at idle.

It could also be the EPA on your throttle servo is off. When you turn on your Transmitter it could be engaging the throttle servo to slightly open the carb just check when you turn it on. Does it move a little. Also check your clutch.
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Old 09-12-2010, 03:35 PM   #3
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Is your idle too high ?
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Old 09-12-2010, 03:55 PM   #4
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Your idle could be too high.

I'm not 100% sure how the T-max clutch works but I believe there is a slipper clutch you could have that too tight.

Or as mentioned above clutch bearings take apart your whole clutch assembly and look it over for worn parts and replace as necessary.

Also on your radio you could have turned the throttle trim too high (Small circle nob) there should be lines or a 0 somewhere around the circle.

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Old 09-12-2010, 03:58 PM   #5
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#1 you shouldn't start your rig until the radio is on and you have tested the throttle and steering to make sure its ok.
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Old 09-12-2010, 03:59 PM   #6
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clutch springs.
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Old 09-12-2010, 04:07 PM   #7
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If it's accelerating after you trun the radio on, then your throttle linkage is probably messed up. You need to set it to where you carb is as far shut as your idle gap allows, when no throttle is applied.
And like the other guy said, don't start your engine until you have your radio on, and have made sure everything is responding like it should.

With you engine off,turn on your radio, and take off the air filter and make sure that when you let off the throttle you carb is closing like it should, and when you hit the brakes the carb is not moving any farther closed then it does with no throttle at all. If when you hit the brakes, and then let off the brakes your carb is opening then your throttle linkage is messed up. You carb shouldn't move at all unless you are applying throttle.
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Old 09-12-2010, 05:12 PM   #8
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Thanks for all the advice. I will check the clutch for sure. Something could have come loose..
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Old 09-12-2010, 05:19 PM   #9
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I'd start by adjusting the idle screw and seeing what happens. Also remember, day to day the engine tune will vary slightly meaning it could need to be leaner or richer depending on the day's conditions.
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Old 09-16-2010, 02:05 PM   #10
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Thanks everyone for your help.. Truck is running pretty good.. Took it to NorCal and ran it on the track for almost two hours .. Had a blast.. Tuning issues or User error.. whatever it maybe but I found the right mix on the carb.. Day to day adjustments seems to be the best advise.. I guess in this case patience is key..
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