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  1. #1
    RC Racer
    Join Date
    Dec 2003
    Posts
    171

    Unhappy cant get my engine tuned...

    I have been trying for days to properly tune my engine. My maxx was already broken in when I got it, but the person never reset the break-in settings.

    So, I have been using the manual and info here on the forums to attempt to tune the engine for performance, but I am not having any luck.

    I cant even get it started without having to recharge my ez start batteries 2-3 times. And then if I can get it started, it stalls as soon as I give it throttle.

    I have read that this can be a comin pain with the 2.5 engine, that people spend more time tuning then driving, but I guess when you finally do get it tuned properly, it makes up for all the time and frustration.

    Anyway, is their any tips on tuning the engine to make it easier? I am using the blue Dynamite brand fuel (20% nitro), same fuel I run through my Nitro Sport with no problems. I start at the factory default settings, and even then I cant start the truck sometimes.

    But anyway, lets say I close the high speed throttle control all the way. They say 4 full turns is the stock setting for breaking in. How many turns would it be for good performance? I just want an idea on where to set it.

    Also, once I get the high speed set, what is a good setting for the low speed? Does it even need much adjustment usually?Would that affect my Idle, because I dont think my idle is set good either, because 9 out f 10 times I cant shift into reverse, it goes into neutral instead and revs up like crazy.

    Thats about all for now. Any help with this would be really appreciated. I would love to get some real use out of this truck before winter comes (and even when winter is here, since I got my plastidip ready ).

    One last thing, lets say I wanted to get a different engine just to rid myself of the tuning issues. Say I went with the Sirio .23 t maxx drop in, what else would I need? Would I just need to use all aluminum gears and shafts in the transmission? Is there anything else that would need to be strengthened? Most likely, I wont be doing this anytime soon due to the price of that engine, but I would just like to know what else needs to be replaced. Thanks in advance, I will eagerly await all of your replies .
    Last edited by Goanna; 09-24-2004 at 09:23 PM.
    -Traxxas T-Maxx 2.5, GH tuned Pipe, GH cooling Head, OS 10D carb, Motorsaver Filter, Venom Failsafe and Temp Sensor, Modified Receiver/Transmitter using 2500 mah NiMH batteries, RPM A Arms and Custom Painted Proline Hummer Body
    -Stock Traxxas Nitro Sport pro .15 (Possibly upgrading to a 3.3 soon).

  2. #2
    Banned by Warnings
    Join Date
    Jun 2004
    Location
    socal
    Posts
    243
    have you checked your glow plug? have you done a pinch test?do you have an air leak anywhere? low speed needle should be flush with inner flange on carb. high speed needle should be 4 turns out for default. i would check glow plug first off.then go from there? check your carb make sure its not cracked anywhere.i came across that problem.good luck. be patient!! get er done!!

  3. #3
    Banned by Warnings
    Join Date
    Dec 2003
    Location
    warwick NY
    Posts
    373
    git er done is rite take your time and if you have too much troble with it do you have a lhs that will help you out....

  4. #4
    RC Racer
    Join Date
    Dec 2003
    Posts
    171
    Originally posted by 2tuffmaxx
    have you checked your glow plug? have you done a pinch test?do you have an air leak anywhere? low speed needle should be flush with inner flange on carb. high speed needle should be 4 turns out for default. i would check glow plug first off.then go from there? check your carb make sure its not cracked anywhere.i came across that problem.good luck. be patient!! get er done!!
    Glow plug is fine

    What is a pinch test?

    Carb is not cracked to my knowledge, but I will double check.

    I was going to take it to my LHS, but the owner went on vacation for 2 weeks and the store is shut down till hes back, and I dont really want to wait that long. The next closest hobby shop is pretty far away, and they arent very helpfull. There are a few ones in the next state over, but thats an even furthur drive, plus tolls . I guess if I cant get it done on my own though, ill have to take a trip to one of the other shops.
    -Traxxas T-Maxx 2.5, GH tuned Pipe, GH cooling Head, OS 10D carb, Motorsaver Filter, Venom Failsafe and Temp Sensor, Modified Receiver/Transmitter using 2500 mah NiMH batteries, RPM A Arms and Custom Painted Proline Hummer Body
    -Stock Traxxas Nitro Sport pro .15 (Possibly upgrading to a 3.3 soon).

  5. #5
    Banned by Warnings
    Join Date
    Jun 2004
    Location
    socal
    Posts
    243
    well you have to be able to get the truck to run before you can apply pinch test.so use default settings.the truck should start and run if there isnt a severe air leak.ok once you get it running do a couple high speed runs.if it seems real sluggish.lean the hsn a 1/16 of a turn.then try again.do this until it seems to have full or lots of power.ok when you reach that point.you move on to lsn.after you do a couple high speed runs where you feel the truck is doing good.bring it in while stilll runing. and pinch the fuel line going to carb.about an inch or two from carb.if truck revs up and dies in about 4 seconds or so.you can call it good.if it dies instantly.richen lsn 1/8 turn.run a couple more high speed runs and try again.you get the picture now im sure!! page 34 in your manual!!good luck hope this helps!

  6. #6
    RC Racer
    Join Date
    Dec 2003
    Posts
    171
    Okay, well I made some progress today.

    I got it to where it starts up almost instantly, it idles good (doesnt jerk forward), and I am able to drive it around without stalling, but if I give it WOT, it dies out, and I still cant shift into reverse (The manual mentions that the idle needs to be set properly for reverse to work, or somethign like that?).

    The manual says that could be that it is running lean, but it is still spitting out fuel as if it is running rich? That has me a bit baffled since I have the high speed needle set lean (unless I am confused here, is counterclockwise lean or rich?).
    -Traxxas T-Maxx 2.5, GH tuned Pipe, GH cooling Head, OS 10D carb, Motorsaver Filter, Venom Failsafe and Temp Sensor, Modified Receiver/Transmitter using 2500 mah NiMH batteries, RPM A Arms and Custom Painted Proline Hummer Body
    -Stock Traxxas Nitro Sport pro .15 (Possibly upgrading to a 3.3 soon).

  7. #7
    RC Enthusiast
    Join Date
    May 2004
    Posts
    25
    Do you have a temp gauge ? Even if you gon't with the fuel spitting out the exhaust and it dying when you go WOT I think you are too rich. I would richen it 1/16 and if you get better performance then you know you are doing the right thing. I would not lean it up too much until you get a temp gauge though

  8. #8
    RC Enthusiast
    Join Date
    May 2004
    Posts
    25
    sorry, I meant to lean it up 1/16

  9. #9
    RC Qualifier
    Join Date
    Sep 2004
    Posts
    271
    lean is clockwise and rich is counterclockwise

  10. #10
    RC Qualifier
    Join Date
    Oct 2003
    Location
    Aurora, Colorado
    Posts
    276
    Originally posted by Goanna


    counterclockwise lean or rich?).
    The more you screw in the HSN (clockwise) the leaner it runs, and the more you turn it out (counterclockwise) the richer it is. How much fuel is spitting out. If it is only a little it may not be something to be concerned about, the oil in the fuel is chosen because of its flash point, the point that it ignites). Generally you will have some oil coming out of the pipe. It sounds like you are too rich. I would try to feather the gas a little and get it to move. I know that when I first start mine that it can be difficult to get it going, and sometimes it is way rich. You could also be partially flooding the engine when you start it. Not recommended, but you could get it started and then pick it up, and feather the gas to get the wheels spinning, and work up to full throttle. When I say that it is not recommended Traxxas says not to run the truck at WOT with it freewheeling (in the air). I have had the truck so rich sometimes that I have to do it and get all of the fuel to blow out of the engine. After you get it to run long enough that the engine warms up it will be much easier to work with.

    Let us know your progress.
    Later
    Codfish

    PS. a call to traxxas with a cordless phone might be a good idea.
    O.M.G. You spent how much..........sorry honey.....I love you!!

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