New T-maxx, need help

[thatguy]

Ok My wife bought herself a new T-maxx, and we got it started last night but have to do the break in today when she gets home. So heres where we are at, last night had it started and the idle would start to go up on its own and it started jumping forward, it would'nt go anywhere just bump,bump,bump,ect. I am new to the sport and have no idea how to fix it and would like some info before she gets home because she kinda got wigged out about and thought her truck was broke. Thanks in advance.

[koolstrike]

Ok My wife bought herself a new T-maxx, and we got it started last night but have to do the break in today when she gets home. So heres where we are at, last night had it started and the idle would start to go up on its own and it started jumping forward, it would'nt go anywhere just bump,bump,bump,ect.

-Are you able to control the front wheels with the remote control (transmitter), meaning is the remote control working the steering and throttle servos?
If the steering and throttle servos DO respond to your transmitter, go ahead and restart the truck. Make sure NEW fresh batteries are in the truck AND transmitter.
Does the truck have new FRESH fuel in it or does it have fuel that may be old or borrowed from a friend?
If the truck restarts and just has a high idle or erratic idle and just goes bump, bump, bump that sounds like the LOW speed fuel mixture is too LEAN. Check the Traxxas manual to see how you adjust the LOW speed idle. Make only SMALL adjustments at a time.


A smart investment would be to buy a temperature gauge so you can make sure you don't overheat the engine and ruin it. A decent gauge will run about $30.

Try these suggestions first and if you still have problems, repost.

[thatguy]

Thanks for the input, and you were right just had to fine tune it.

Which brings up another question,, I understand the whole lean and rich mixer varies with outside temp, but if I have set my low needle is it set now or will it have to be set everytime I mess with the mix needle?

Also should there not be ANY unspent gas coming out of the exhaust?

[koolstrike]

Which brings up another question,, I understand the whole lean and rich mixer varies with outside temp, but if I have set my low needle is it set now or will it have to be set everytime I mess with the mix needle?

-GENRALLY speaking you do not need to adjust the low speed mixture as much you adjust the high speed mixture. High and low speed mixtures vary not only with temperature but also elevation and humidity changes.
To answer your question yes you will need on occasion need to adjust the low speed mixture.

Also should there not be ANY unspent gas coming out of the exhaust?

-There ALWAYS should be some upburnt gas coming out of the exhaust. Get yourself that temp gauge, it will help prevent you from overheating and burning out your engine. You cannot tune by temperature alone, as you progress in the hobby you will learn how to "hear" the engine note and compare it engine temps to adjust the fuel mixture for optimum power and response.

[thatguy]

Thanks for the input.

So correct me if I'm wrong.....running temp should be around 220-230 and to raise the temp lean out which is clockwise.???

[koolstrike]

So correct me if I'm wrong.....running temp should be around 220-230 and to raise the temp lean out which is clockwise.???

--Temp should be around 220 to 230 is correct. HOWEVER, you can have a car in the 220 to 230 temperature that is either too rich or too lean. So yes, shoot for that 220 to 230 temp once you get the car running cleanly, meaning it is not too rich (or lean) on the high speed screw. Too rich and the car has no top end power, too lean and the temperature goes too high.

Same with the low speed screw, too lean and the engine tends to have erratic or high idle, too rich and the engine will "load up" and idle poorly. By the way an RC engine if tuned correctly WILL begin to load up if you let it idle 5 to 7 seconds.

To lean either the high speed or low speed mixture screw the mixture screw IN (clockwise); to richen the mixture, screw the mixture screws counterclockwise.
What you are doing when you screw in the mixture screw is you are making the hole where the fuel enters the motor smaller, which allows less fuel into the engine, thereby leaning the mixture.

Hope that helps.

[thatguy]

Yes your a big help, its running great now, she has burned almost 3/4 of a gallon today and its 9:30 at night and she is still running it as I type this.

[koolstrike]

I would also suggest buying a "Fail Safe" so that when the batteries get low on either the transmitter or receiver you do not get a "run away" condition and have the truck lose control and literally "run away" have alot of damage from hitting something.
Also, don't forget to clean the air cleaner, every 45 minutes of running (and more frequently if dusty conditions) remove the air cleaner, clean and re oil. Traxxas includes extra air-cleaners, so always keep one clean and oil and in a plastic bag, ready to install. Once you change the first air cleaner, clean it so it can dry. Once dry, oil it and put it in the bag.

Also, use a zip tie to secure the air filter to the carb, dust can get into the base real easy and destroy the motor.

[LSXEric]

What engine is it? If its the 3.3 its okay its tourqey by design. The 2.5/2.5r mabye turn the idle down little by little.
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Look at my avatar, its a T/E-maxx hooters body. I (heart) hooters!

[thatguy]

It is the 2.5.