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Help needed! - Hardest to run engine I've ever found (MGT 4.6)

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Help needed! - Hardest to run engine I've ever found (MGT 4.6)

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Old 01-24-2008, 05:15 PM
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Cabbage
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Default Help needed! - Hardest to run engine I've ever found (MGT 4.6)

Hey all, I need help with an engine. It's my friends MGT 4.6. When he first had the truck about a year ago we tried to start it but found it would only run with the glo starter attached. After lots of mixture adjusting and resetting we solved the problem by changing the glo plug (despite the fact the original one worked fine). After break in the truck ran fine for a while before being left around for a while. When trying to get it going again a month ago he had the same problems, it would run with the glo starter but then cut out after 2-10 seconds of running without the glo starter. Tonight I sat down and gave myself a good couple of hours working on it. I tried 3 different glo plugs all of which worked. The one I spent the most time with was an MC-59. After resetting the needles and and then leaning the high speed probably about 1-2 a turn to 3/4 of a turn the truck would run for about 10-20 seconds (after being driven around with the glo-starter on for a minute to get the engine up to about 180F (air temp is about 45F)). Then as I continued to tune the run times started coming down again. There is a lot of smoke coming out of the exhaust but the behaviour is lean such as stuttering on acceleration and full cuts outs if I go to full throttle. Operating temps are around 160-180 but are pretty irrelevant because its not running consistently or long enough to get a proper reading.

I have tuned Traxxas engines, Thunder Tigers (easiest engines to use and tune ever!), an RB 523, a team Orion .12 touring car engine and a Picco P2 .26 engine but I have never come across an engine as hard to tune/run as this associated 4.6. Does anyone have any ideas what the problem could be? Fuel pressure is there and the engine is pinching the carb tight so I doubt theres an air leak there.

I look forward to your replies!
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Old 01-24-2008, 06:06 PM
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Default RE: Help needed! - Hardest to run engine I've ever found (MGT 4.6)

Check the back plate for leaks.
Usually they are sweet engines and hold a tune well.
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Old 01-24-2008, 07:02 PM
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Default RE: Help needed! - Hardest to run engine I've ever found (MGT 4.6)

Yeah, the MGT is known to have the easiest stock motor to tune.

I love mine with over 8 gallons through, it could be an airleak or bad tuning. I know you've had several vehicles, but maybe the pipe is throwing you off or something...
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Old 01-24-2008, 07:07 PM
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Default RE: Help needed! - Hardest to run engine I've ever found (MGT 4.6)

^^ Wut he sed


I have tuned Traxxas engines, Thunder Tigers (easiest engines to use and tune ever!)..
The MGT 4.6 is a Thunder Tiger motor.
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Old 01-24-2008, 07:14 PM
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Default RE: Help needed! - Hardest to run engine I've ever found (MGT 4.6)

lol


I didn't even see that! lmao!


Are you really sure that the engine is running lean?
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Old 01-24-2008, 07:56 PM
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Default RE: Help needed! - Hardest to run engine I've ever found (MGT 4.6)

ORIGINAL: duckedup
The MGT 4.6 is a Thunder Tiger motor.
Fair enough, I wasn't aware of that! I'm sure it's a pretty good motor normally and I'm fairly certain mine has some kind of fault because if they all ran like this there'd be some kind of product recall!

I haven't checked for air leaks, would the backplate be the main place to check?

And no I'm not sure whether it's running lean... I'm not sure of anything anymore lol, this motor is destroying my soul! [&:]
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Old 01-24-2008, 08:13 PM
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Default RE: Help needed! - Hardest to run engine I've ever found (MGT 4.6)

lol

Anyways, yeah. Find some something sort of like [link=http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXSF70&P=ML]this[/link] and seal up the needles on the carb. Just unscrew them, put the sealant on the o-rings, and screw them back in.

As for the backplate, see if all the screws are tight first, and if the carb isn't the fix, you need another type of sealant, but I totally forgot what kind it is. maybe someonee can help me here...

Also, I believe a member, scottywilkes, may have had a problem like this with his front crank bearing. I'm not sure if that caused this sort of problem or just instability, but maybe give him a PM.
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Old 01-25-2008, 01:59 AM
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Default RE: Help needed! - Hardest to run engine I've ever found (MGT 4.6)

u said its only runnin 160 u talkin faren? If your talkin celsius 160 is way to lean, thats over 300 faren, around the 130celsius mark is kinda where u wanna be, when i take a reference once i have the motor tuned, my motors usually hang around there

If your talkin 160 faren, your way to rich, lean the HSN a bit more, about a 1/4 turn, and go from there, my TTR28 ran best around the 270 mark, and its still to die with 14 gallons on it lol
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Old 01-25-2008, 02:01 AM
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Default RE: Help needed! - Hardest to run engine I've ever found (MGT 4.6)

nah my rear bearing completely let go, wasnt leaking, just shat its self lol, new bearings from AE under warranty and i was off again, its down and out at the moment because of a screwed rear bearing again lol
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Old 01-25-2008, 08:11 AM
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Default RE: Help needed! - Hardest to run engine I've ever found (MGT 4.6)

If you have tons of smoke pouring out of the exhaust pipe w/unexpended fuel your running it way to rich, which will also cause it to stutter and cutout, I.E. to much fuel and not enough air in the mix. Also your running temps are to low, that motor should be operating at minimum 220 degrees to have good power through out its rpm range. If your starting that engine in cold weather you might want to use a hairdryer to heat the motor up before you start it, makes it alot easier Reset to factory settings, turn the HSN 1/4 turn lean, heat with a hairdryer and then fire it up and go from there. Just remember that colder weather requires you to run leaner to get the motor to the proper operating temperature range.
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Old 01-25-2008, 06:51 PM
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Default RE: Help needed! - Hardest to run engine I've ever found (MGT 4.6)

It was 160 Farenheit not Celcius.

Problem seems to have been cured My friend had taken the backplate off to remove his broken recoil starter, I took it off to check it and oil looked like it had escaped across the surface. So I cleaned up the surfaces, found some hermatite gasket sealent and resealed it. THen fueled it up and it ran fine, was popping lifts and temps running about 260 tops.

Cheers for the help fellas!
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Old 01-25-2008, 06:55 PM
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Default RE: Help needed! - Hardest to run engine I've ever found (MGT 4.6)

See its a good motor
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Old 01-25-2008, 07:01 PM
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Default RE: Help needed! - Hardest to run engine I've ever found (MGT 4.6)

You have to richen your needles in winter and lean them in summer. Cooler air is more dense than hot air therefore more oxygen, so if youhave more oxygen you need more fuel to keep your fuel-air ratio right. Every engine I have run in cold weather hadto be richened at least 1/2 -3/4 turns from where they run in summer. Lean is hot and rich is cold but what is rich in summer can be lean in winter.
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