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Picco max has me scratching my head

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B

Bash

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I bought a picco .26 max off ebay. It supposedly had under a gallon ran through it. When I got it, I sealed off everything with RTV copper. Back plate, carb, needles, everything.

It's about 55 degrees F here today so I took it out for some testing. I have a problem that developed about 5 minutes into testing. The truck is running at about 200 degrees with a nice blue smoke trail.

The problem is that when I accelerate, the engine will cut out, but NOT bog. This isn't a bog problem that I would associate with being to lean. I've fiddled with the needles and nothing.

The engine simply acts as if I'm chopping the throttle. Say I accelerate and keep the trigger at a steady 3/4 throttle, the engine in the car will rev up like it is supposed to and then idle back down, then start accelerating again and idle back down. I took the engine off and noticed I had a leak around the exhaust header, sure enough I forgot the header gasket. I put a new one in and tested again... but nothing. I have changed glow plugs aswell and same thing.

The servos are working fine. That is not the problem. I have tightened the head bolts and the carb is tight...

any help?????
 
I tried richening it up to the point that it was very sluggish off the line with lots of blue smoke, but it would still cut out.


I picked the truck up and gave it a constant half throttle and it would just just as it did on the ground. I noticed that the throttle servo arm was actually closing and opening like it was fighting to keep a signal.

The thing is when the car is off the throttle servo works perfectly and doesn't flucuate at all.

What could cause that?

BTW the grass was a bit wet and I was running with the body off, but how could this explain the servo working perfectly with the engine off?
 
found the problem.. the wires connected to the throttle servo chip were ripped away...

can these be soldered back together?
 
Well I tried soldering but failed. Hands aren't steady enough LOL

So I put an old 2018 traxxas servo in. It works alright for the time being. Gonna pick up a hitec 645 as soon as I can.

Otherwise the truck runs awesome. Wheelies like crazy. I'm just waiting for something to snap in the drive train! LOL
 

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