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random throttle cut out

Old 05-03-2008, 08:07 PM
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Ziggy46802
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Default random throttle cut out

I have a completely stock T-Maxx 3.3 and it runs fine but sometimes (probably every 2 or 3 tanks) all of a sudden nothing happens when I pull the throttle trigger and the car is just sitting there idling (it's not a problem with the throttle arm, but with the servo). I can move the wheels just fine so I don't think it's the batteries (even though I do use rechargeable 1.2V batteries for both the car and the transmitter, I charge them often). Usually to get the throttle servo to work again I just turn the switch for the receiver (on the car) off then on, it takes 2-3 seconds to "turn on" and then I hit the throttle and the car zooms off. The throttle arm doesn't seem sluggish or anything so I don't know what could be going on. The car is about 1.5 years old but it doesn't even have a gallon of fuel in it because I only ran it a little when I first got it and now I'm starting to run it again (reason I stopped running it before was that I broke some stuff that my local hobby shop didn't have at the time) so I don't think the servo's are dead yet and the steering works fine and the wheels have never just stopped turning all of a sudden on me before so it's only with the throttle servo itself. Sometimes after a tank or two it'll happen, I turn it off/on (the electronics not the engine), I start going and then bam the throttle cuts out again after driving a few feet. Sometimes it happens, I turn it off/on and then it doesn't happen again for awhile. Turning the transmitter off/on doesn't work, only turning the receiver off/on. Any advice would be much appreciated!
Old 05-03-2008, 08:52 PM
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systemlord
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Default RE: random throttle cut out

Its got to be a bad on/off switch, sometimes the metal contacts in the switch can get hot if theres a lot of resistance. I had a throttle servo die on my real slowly, at first when I let go of the throttle trigger, for some reason instead of slowing down it would rev then return to neutral or idle. Shortly after two weeks of this the servo started having the twitches almost like it didn't no what to do.
Old 05-03-2008, 09:10 PM
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Ziggy46802
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Default RE: random throttle cut out

Wouldn't that affect the steering too though? Right now I have taken apart the throttle servo and found out that there are 2 rods in there and I think they might be loose so I'm glueing them down onto the servo. I think the problem was that the middle rod would come out of its hole so the bottom most gear could wobble, which would make it so it couldn't transfer to any other gears, which results in the red light above "function". Glueing them down would make it so they cannot become loose. I'll check out the on/off switch too though. Should I be able to see the problem or will I just have to get a new switch?

EDIT->Whenever the throttle dies the car will all of a sudden stop (I've never had it happen while I was going very fast luckily) and then, after my confusion for a second, I realize the throttle servo died. It happens in an instant, the servo doesn't slowly die down.

EDIT2->What I thought was probably wrong since, after putting the top of the servo on, the rods don't seem loose so I doubt the problem lies in the servo itself. I'll check out the on/off switch though.

EDIT3->I was just playing around with it and I turned very hard (directly to max) and it happened. The throttle was stuck a little bit higher than idle and I got the flashing red light above "Function". I tried doing some more hard turning and after a little bit (a few hard turns) the flashing red light went away, green light came up, and my throttle was working again. I was doing all of this while the engine wasn't running too. The throttle shut off within a minute of turning the car on too (just played around with the throttle, then it cut out right when I did a hard turn).

EDIT4->Right after posting EDIT3 I tried it again and about 3-4 seconds after turning the car on it happened. I turned it on, started slowly pushing in the throttle trigger and then it happened about 2 seconds after starting my throttle pushing. I was doing it slowly too (I wasn't very far into the throttle when it happened) so I guess it's not sudden max throttle/steering that triggers it and now I know steering doesn't trigger it either, it's just random. When it happened the throttle arm suddenly shot back to slighting braking and then the red flashing light came on so I couldn't do anything. After waiting for a little under a minute I got my throttle back. This happened while the front tires were sitting on the ground, making them not be able to turn very fast or very far while the car is not in motion. This is making me think that the problem is the rechargeable batteries. The batteries are only 1.2V instead of 1.5V like normal batteries so maybe doing something like steering hard while the car isn't in motion (something that would probably take a lot of energy) takes too much energy for the steering servo and doesn't let the throttle servo have any energy, resulting in it cutting out and you have to wait until energy can get back to it (this is the only weird part, it takes awhile even when I'm just sitting there doing nothing). Would this probably be the problem and I should get normal batteries or is it probably just the on/off switch?

EDIT5->I checked out the on/off switch and it looks fine, nothing seems to be wrong with it at all. Sorry about all these edits too, it's just that I don't want to double post and all these edits happened in a few hours of each other anyway.

EDIT6->Well in the next few days I'm hoping to buy the reciever battery pack and wiring harness which will resolve the problem if it's the rechargeable batteries fault or if it's the faulty on/off switch's fault.
Old 05-03-2008, 11:59 PM
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systemlord
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Default RE: random throttle cut out

Very strange indead! Have you tried another servo for throttle to rule out the servo as the fault? I'm also thinking can your radio/servo could be going into fail safe mode because of using weak regular AA's instead of the nicad or NiMH batteries that these radio were designed for? One thing, when you post can you break-up your huge paragraphs into many little one's please.
Old 05-04-2008, 08:39 AM
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Ziggy46802
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Default RE: random throttle cut out

Well I don't have a failsafe unit on it so it can't be that (unless the 3.3 comes with one already installed?) but I think it's just the batteries. I do have some old servos from an old T-Maxx so I'll try replacing the servo and then running it later to see if it ever happens. Even if it fixes it I'll still get the battery pack and wiring harness though.

EDIT->Well I just looked it up and saw that it does come with a failsafe so that's probably what it's doing. The optidrive only looks at the voltage for the throttle/shifting servo's and if it's too low then the flashing red light will come up and it'll go into failsafe mode (slight braking). You can still steer though so that would perfectly explain it. The only problem is I remember it happening shortly after replacing the batteries (charged up rechargeable ones). I guess rechargeable batteries just have too low of a voltage for it even if charged. They seem fine in the transmitter though since I haven't gotten the flashing red light on it yet, but would a lower voltage with rechargeable batteries affect the signal at all?

I'll just put in some real batteries so I can run my car until Tuesday afternoon, which is when I can get that battery pack and wiring harness.

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