Please help.My son's Ofna ultraLX comp keeps trying to run away.We have put new batteries in the radio and the reciever on the car,but still loose control.We tried testing to see if the servo reacts.from several distances and it seems to react fine while the engine is not running.But when he tries to drive it around it does not respond the way it should.It seems to be both steering and throttle but not so bad on the steering.The throttle not responding properly is the big problem.We are fairly new to the hobby and this is my first post,but what a wealth of information on this forum.Please give us some advice on how to test or trouble shoot this problem.

Thanks everyone!
Larry E.

Make sure the crystal is in all the way into the receiver and the transmitter. Make sure nothing is loose on the car, and no metal to metal contact. You receiver might be shot also but the above should help.

My advice to you...get rid of that AM radio(asuming you still have the original radio in it)...it's junk and will glitch from the radio noise generated by the engine and/or any metal to metal rubbing. You can try pulling your pipe out of the header coupling a bit, sometimes they rub together and create glitch city with AM radios. Really, you should be able to find a DX2 on ebay for next to nothing...no more glitches or signal interference.

Before we deduce that the radio set is the culprit, try the following few things-

+ Make sure the receiver antenna wire is complete and not cut or frayed anywhere. To be completely sure, run a continuity test from the end of the antenna to where it solders into the receiver (will have to pull the receiver case apart); should be 0 ohms.

+ While you are in the receiver, look for any sign of water intrusion or foreign matter.

+ Make sure the antenna is fully threaded in the transmitter

+ Pop the crystals out of the car AND the transmitter and verify that you get a nice positive engagement; on the receiver, use a ziptie to secure the crystal into the receiver. I usually also ziptie the servo leads into the receiver as well

+ Pop the servo horns off of the servos and make sure the servo teeth or the horn teeth aren't stripped- where it would grab sometimes but maybe not others.

+ Make sure the throttle servo and linkage smoothly moves the slide valve in and out of the carburator. If the linkage is setup wrong or at a bad angle, it can bind when going in and out and get stuck.

It could be a case of a bad RTR radio set. If I tried the things above, I would replace the radio set (TX/RX). It can be an AM set if you are on a budget. Typically for RTR 1/8 scale buggies, you could move the stock steering servo up the the throttle position and then get a decent metal gear servo for steering (Hitec MG645 very popular)

Also, if you are close to power lines or a radio tower or cell tower, those can cause interference. Maybe run the car in a different spot and see if it works any better.

Good luck!

Thanks alot guys!

I had a customer that had two different Ofna cars run off on him 3 different times. Turns out the receiver crystal went bad. 3 different crystals.

He replaced his radio with a Spectrum, and let his kid have the good crystal for the stock radio, and has not had a problem since.

Kind of unusual to have that many bad crystals. The only bad crystal I've had in almost 20 years was one I stepped on! [X(]

Rotor

BY-PASS the power switch on the car, this is a problem i had and took for ever to figure out, worth a try

my two 2 cents i have notes that my car would remain exallrated even after fully closeing the carb it would take 2 to 3 seconds to die. this was do to the fact that my carb was loose. making my car continue to run even after hitting the break.