Help, I need an exorcist!

[FieldDoc]

Hi,
I am a real noobie to the hobby and I have a brand new HPI RS4 3 RTR. When I first got the car and was going through the initial 'getting ready' steps, such as fitting the batteries, I noticed that the steering and throttle servos were twitching, just a little bit, when the car was turned on and the radio was on. I thought nothing of this (being a noobie, I figued it was harmless interference or something)....
.....Shortly after getting the car started, the car took off (straight into a damn wall....fortunately, the car was only superficially scratched). Since this accident (ie, during the remainder of break-in) I have had the car on a block to keep the wheels off the ground...but twice during the tank, the car just caned it into full throttle and I couldn't stop it with the radio. It also twitches the wheels as well. This only seems to happen when both the car and radio are on. If the car and radio are off, but I have the engine running.....it idles fine.
Does anyone have a clue what could be causing this? I have checked all the cables for a loose connection, double-taped the radio and batteries in place in case it is a vibration problem but still the problem persists. I have almost finished the break-in cycle, but there is no way I am letting this car loose if I can't control it!!!!!
Help!!!!
Thanks
P.S. The tqitching seems worse if I move the transmitter around.

 

[M@xximillion]

Something close to you is interfering, try taking it someplace else to be sure it's outside interferance and not the electronics. Outside interferance could be caused my a number of things so it could be anything electronic, broadcasting or an electric motor running.

 

[NCNitro]

Make sure there is no metal to metal rubbing, this will cause glitches. If it is an outside interference causing the glitch, try changing the crystals to a different frequency. Also make sure your batteries are good. Buy a fail safe.

 

[FieldDoc]

I suppose it could be interference, although it has happened in two different places, about 2 miles apart. What do you mean by metal-to-metal rubbing? What components in particular? Also, when I said the car launches into full throttle, the only way to stop it is to shut the engine off - its as if the radio becomes useless!
I thought an RTR car would be easy to use!!!

 

[x_789]

If it goes full throttle and you are right next to it I am wondering if you are using new aka GOOD batteries. Next I would look at my trims they are the little knobs on the Transmitter that center the servos. Turn on the RX and TX but dont start car make sure you have the throttle centered so that its the carb is closed when you dont give its in a nutral postion and make sure that the wheels are centered. Also Does it glith while the car is the engine is not running...X

 

[SkyMaxx]

Loose metal to metal contact is a source of pain for anything electronic once it starts vibrating. The source of the vibrations is usually the engine running.

If the controls (servos and radio) are glitching with the engine off, then you have an outside source interfering with your receiver. This could be something as simple as radio source close to where you are operating or something as insidious as a powertool running nearby.

If the glitching only shows up with the engine running, then you most likely have something loose in the metal to metal area. Check all screws for tightness. Check out all areas where you have metal to metal contact. One of the biggest trouble spots is the engine mounts themselves. If you have a metal chassis plate and you do have a metal engine mount, and they are not tightly secured...once the engine starts hitting any level of rpms, the vibrations will start to generate what is known as EM (electromagnetic) interference. This causes servos to glitch and in the extreme to rotate to the full extent of their motion (ie way open throttle).

Hope this helps.

 

[NCNitro]

FieldDoc, remove the screws holding the engine to the chassis. HPI does not use locktite on these and they will fall out, trust me I know. Locktite these screws before you run it.

Also if you have not already done so install a fuel filter.

 

[FieldDoc]

I am getting twitches of both servos with the engine off. However, the throttle has only thrown itself fully open when the engine is running. I will check the screws for tightness and buy some threadlock for the screws. Out of interest, Would not having threadlock on the screws cause them to vibrate on the aluminium chassis and cause EM interference?
Before I do anything else though, i'm gonna fit the failsafe I bought yesterday!

Just a quick update. The servos seem to twitch when I move the transmitter...if I keep it perfectly still it doesn't seem to twitch

Actually, scrap that...it definitely happens if I touch the antenna on the transmitter......although it is screwed in as tight as possible

 

[NCNitro]

How are the batteries in your transmitter, with my RS4 3 if they start getting low on juice my servos also act eratically. You might also have a bad connection to the antenna inside the radio, like possibly a cold solder joint or something similar. Do you have a friend with another 27mhz radio you could try to see if it is indeed the radio causing the problem?

If the engine screws are loose this will cause twitching but usually only if the car was running. The reason I mentioned the locktite is two of my four screws fell out right after I first bought mine when I thought RTR meant ready to run. Its obvious HPI does not know the benefits of threadlock.

Once you get these small problems ironed out you will have a blast...trust me, don't give up. Nitro RCs can be very frustrating at first. But once you get the hang of it you will be addicted.

 

[Lason]

Another thing to look for is to make sure the antenna wire on the car is not touching any metal or graphite. If it is that will deffinetly cause glitches. I have never seen an RS4 up close but those touring cars dont have much room and something could be rubbing on it. Just another thought. Also if you have a buddy with a spare am radio, try to switch crystals with him and see if it still glitches and if so use your reciever and his radio with a matching set of crystals. IMHO these RTR radios suck.

 

[FieldDoc]

Thanks for the suggestions guys....have now fitted a failsafe and will speak to my brother and try to use his crystal and see if that works.
Can I ask an unrelated question? What do you guys mean when you talk about leaning the fuel? The reason I ask is because my car will only start if it's given about 1/3 throttle (ie the hole under the air filter is set about a 1/3 of the way - instead of the 1mm it is supposed to be according to the manual). If I close to this said 1mm - I can't get the engine to start - or it starts then stalls.

 

[x_789]

Your stalling is more than likley because the engine is cold. You also have then enigne super "RICH" which means lots of fuel going in... You run a engine rich on breakin so that it has plenty of oil... Lean is the opposite lean means you turn the needls clockwise which will close them this is the highspeed and low speed. The thing you are moving to open up the carb is called the idle screw that adkust how much air comes in when the car is idling the reason you have to open it so wide to start it and keep it running again is because you are running so rich. Once the motor is broke in you will lean it out and then you can close the hole more becuase less fuel will need less air.. Also you can close it some now down to 1.5 -2mm and when you start it hold your transmitter in one hand and give it some throttle a couple times before pulling then hold it about a 1/4 throttle this will do the same as having the carb opened so far. Also once it warms up when you let the throttle back to nutral it should idle closer to normal....X

 

[NCNitro]

X the RTR3 has a single needle carb, before I replaced mine with an OS I had to open my throttle some to get it started. I did it by using the throttle trim on the remote as opposed to constantly messing with the idle screw.

I hate to tell you Fieldoc, but that single needle carb is crap. Replace that as soon as you get a chance, I would wait until after break in though. Mine never really ran well until I replaced that stock carb, then it was like a different car.

 

[x_789]

That is Sad that companies even put out single needle carbs anymore. I know that are supposed to be easier to tune but come on they are junk...X

 

[NCNitro]

I totally agree with you X. My RS4 3 ran like total crap until I put the OS carb on it. What a difference!! It runs great now. It would never idle right before, you had to compromise high speed adjust and idle because of that stupid single needle carb. I always had to mess with the throttle trim just to keep it idling.