Run away ! Help needed
 

Hi

I have recently purchased my first nitro powered buggy (HPI Trophy 3.5)
I have had electric cars in the past so have a small bit of experience,
But no amount of my experience prepared me for what happened on my maiden voyage today,

I had my buggy all set up and ready to go,
I firstly warmed it up letting it idle for a few minutes and then off I went,
Everything was going perfect for around five mins, then I started noticing slow response of the steering followed by slow response of the brakes, then all hell broke loose and the Car shot off at full speed, nothing I could do about it. Luckily it flipped over and a shot over and pinched the fuel line.

The buggy is fitted with fail safe, which applies the brakes in the event of signal loss, so I know it's not this. It is a used buggy so had been run in.

I'm at a loss as to the issue as nothing's sticking and all is free.

The only possibility I have been informed of is it had upgraded servos (Etron digital) or so I'm told. And somebody mentioned the AA battery's in the receiver have insufficient power and will result in the car running away when low power is registered .

Any ideas on my problem?

Cheers guy

The fail safe will only work if there is sufficient voltage to move the servos into the fail safe position. It sounds to me like your AA batteries went dead. I assume they're just alkaline batteries? I'd invest in a rechargeable Nimh battery pack.

Yes standard AA energiser batteries, I've ordered an HPI rechargeable pack.

Do you think all those symptoms point towards flat batteries ?

Yes.. Def. sounds like dead batteries to me...

Yes, without a doubt.

Yep. Fail safes only work when there's electricity available. Dead batteries = no electricity.

You also should consider investing in a throttle return spring which may help when the battery dies by pulling the throttle servo into a closed position. The spring requires no electricity.

Let us know if it is the batteries. I had the same thing happening to me. And I'm not sure, but I think on one occasion I made sure that my batteries was charged, and I still had a runaway. I have a failsafe too. I checked my failsafe to see if it works by turning on everything except the engine; then turning off the transmitter. The failsafe did its job. Then while having everything on except the engine I moved the throttle and brake servo back and forth with the transmitter and noticed that after a while that the servo would get stuck in WOT. I checked the linkage, spring and boot. Nothing seems to be binding. I did see a kink in the boot, but I don't think that's the problem. So, I came to the conclusion that it's the servo. Haven't had a chance to drive it cause its cold outside.

True, a stuck servo will not be helped by a fail-safe or TRS. I still say that your best insurance is a strong TRS, it works.

For sure this is your batteries going dead. Investing in a good rechargeable pack of some kind will be money well invested. I did this same thing when I was a kid with my first nitro car. You'll never forget this now that it happened once.

Also make sure the fail safe is setup correctly. It should be also sensing voltage and 'fail safe' before the voltage gets too low to activate!! Furthermore it sounds to me that it's reversed going to WOT instead of neutral or full brake.

You also need to put a throttle return spring on the slide valve on your carb to make your throttle servo close it when your radio goes nutzz! there is one made by dynamite and a rubber band made by gmk supply that does the same. This is a must have when you run nitro as it will keep your car from running away.

Always charge receiver pack and radio batteries when running glow. I was breaking in an airplane and have the receiver pack go dead on me...I had to hold the plane in place for 10 minutes at full throttle until the fuel ran out...that wasn't fun either :)

The neck of a balloon does the trick too and much cheaper! Been using them for years...