Please help me get my R/c tuned

[truggy83]

Hello, I have just completed my project but it seems to have some tuning problems. First off I have adjusted the servo and linkage to where it closes all the way at the neutral position. Tell me if this gap looks ok for a good idle speed. This is with the transmitter and car on and in neutral.

Here is the position at full throttle. Notice how the Throttle only appears to open about half way instead of fully. I don't know how to fix this because if I move the rod so it pulls the throttle more, it than doesn't close the throttle enough in the neutral position. It is like you change the position of the rod and it changes both the throttle stop position and full throttle position. I don't know what to do.

Full throttle. Only open about 1/2 way.

Linkage at neutral position

Linkage at full throttle

Can you please help me so I can get this adjusted right now that I got all the right parts.

 

[truggy83]

Car is not starting. If I prime the heck out of the engine it will attempt to start however as soon as that fuel is burned off it goes back to not even trying. Glow plug is working like it should. I end up flooding the engine just trying to get it started. The only thing I adjusted was the carb idle position. I also have installed a muffler which the car never had on before when I ran it. The muffler is of an OS engine off and HPI. I plan on installing the factory traxxas muffler once the parts come in. The thing is I ran it last night for like 10 minutes and it ran fine. I didn't change any of the needle setting or anything since than and it started later last night but would die as soon as I hit the accelerator. Now today it barely even tries to start. I removed the fuel filter and installed a different fuel feed line and that didn't seem to help any.

here is what it is doing.

 

[charliejp]

Reset that carb to factory settings. On those OS motors they're set pretty darn rich to begin with so lean that sucker out from there. Sounds like you're just too rich. As far as you the linkage, I'm not too familiar with that model.

 

[truggy83]

I turned both the high speed and low speed needles all the way until they were tight. I backed the high speed needle out 2 full turns and the low speed needle 1 3/4 turns. The car starts up and will idle but dies if I let it idle after a few seconds and it dies if I give it gas. The engine that is in it in the trx .15. I couldn't fit the os engine in. I also turned the idle screw so the carb opens up a little more so it matches the picture in the manual. It still just dies after idling for so long or if I give it throttle.

 

[Fuel Crazy]

When you took the pipe off....i didnt see you disconnect the pressure line. Do you not have a pressure line going to the tank? If not...thats your problem, you have no fuel being pushed to the carb other then what you prime it.

 

[truggy83]

the car has a pressure line fitting at the manifold that I hook up to the tank. That is how I got it. Here is a video of how it acts not that I set the settings back to factor. I just don't understand how it won't even idle with the factory settings.

 

[charliejp]

I've never had a car with that pressure set up. Is there a place to connect the line on the pipe? If so, plug that hole at the manifold and reroute to the pipe. If not, pull that apart and make sure that it's not blocked or plugged with old fuel.

 

[truggy83]

What can I seal the manifold up with? I somehow just had it running a few minutes ago. When you pull the trigger all the way back it bogs down and the engine doesn't even accelerate like it should. If I blipped the throttle a couple times it managed to get up to speed. I ran it for a good ten minutes. When I tried to start it again it acted like it was flooded.

 

[truggy83]

I tried turning the high speed needle down 1/8th at a time. Most of the times when I turn it the engine dies. Sometimes the engine starts back up sometimes it doesn't. The high speed needle was only about 3 full turns out from being all the way in when I started adjusting it. Stock settings are 2 full turns out from being all the way in. Does changing the hi speed needle change something else cause I can't see why it is dying when I turn it clockwise 1/8th turn.

 

[Fuel Crazy]

have you tried a new plug in it? I dont see how having the pressure coming from the manifold right off the head would give it proper pulse though..

 

[bgbdwlf2500]

I tried turning the high speed needle down 1/8th at a time. Most of the times when I turn it the engine dies. Sometimes the engine starts back up sometimes it doesn't. The high speed needle was only about 3 full turns out from being all the way in when I started adjusting it. Stock settings are 2 full turns out from being all the way in. Does changing the hi speed needle change something else cause I can't see why it is dying when I turn it clockwise 1/8th turn.

3 turns out and it dies when you're turning it clockwise or "in" as you say, you're probably leaning it too much... go the other way and see what happens

 

[truggy83]

Ok I found a little more info for you guys. I don't know how it runs off manifold pressure but it does and I don't believe that is the problem as it ran fine before hooked up to the manifold. I may have found some of the problem. As of late it has been starting up and running and even idling for me. I am thinking maybe it was somewhat out of tune and I got it pretty close to running good. Adjusting the hi speed needle was making it cut out. Luckily I notice that if I turn the trim on the transmitter a little that the acceleration almost doubled and it will now due full acceleration take offs. If I turned the trim all the way up, the car would accelerate on it's own and you would have to hold the brake in for it to stay still or turn the trim down.

I set the trim in the middle and it now no longer bogs down upon hard acceleration and it doesn't move on it's own at idle. I do believe that something is off with the throttle and brake linkage though. I was messing with it today and the car barley has any brakes and it seems like the throttle is not opening up all the way.

While running the car I got a little too excited and it took a nasty cartwheel off a bump that I didn't think the car would catch air on which broke the rear shock support. Here is a video of it running after I set the trim about halfway and was varying it throughout the run. I still believe the car isn't accelerating to it's full potential and I believe that is partially due to the servo horn and throttle linkage not being adjusted right along with it maybe still being a little out of tun. I will take some videos of the throttle linkage setup and maybe someone can point me in the right direction about how it should be adjusted.

Here is the video of it running after I adjusted the trim and broke the rear shock tower Actually in the very beginning of the video when she goes outside and you see it laying on the blue tarp is right after it wrecked and landed on the tarp breaking the shock tower. At the end it flipped and shut off however it did start back up and run until I called it quits. Didn't want to break anything else for the day.

 

[truggy83]

I made a video of how the throttle servo is set and how it reacts. It seems like it moves more for the brake side than the throttle side. I took the servo apart and everything fell out. I managed to get all the gears back in correctly and none of them looked worn. It makes a buzzing sound and shakes a little when you hold the throttle or brake in. The batteries are fresh and it did this before I had it apart. Sometimes when you stick the glow plug starter in to start it, the servo moves when the glow plug starter touches the cooling head like there is some ground issue.

With the trim in the middle or close to it (my transmitter has no 0 indicator) the throttle on the carb opens at max halfway. Sometimes the servo moves the carb a little less than half and sometimes it opens closer to half way. If I turn the trim all the way so the throttle is open more at idle and the carb is not resting against the throttle stop, the car moves on its own at idle, but the carb opens up a little more past halfway and the car has better acceleration. If I have the trim in the middle the carb has the 1 mm gap for a good idle without it driving off but the carb only opens half way max. Is there something wrong with my setting or servo? or is this normal.

Here is the video I made

 

[truggy83]

Just started it up and the wheels are spinning. When I hit the brake it dies. The carb is adjusted down to 1 mm. I don't understand why it is doing this. When I took the engine out the clutch shoes and spring looked good. Not sure why it is doing this.

 

[Metalhead Matt]

Does it idle until you hit the brakes?

 

[truggy83]

here is the video with it accelerating on its own.

at the end I believe it dies because the fuel tank was low and tilted at an angle. It does have to do with the location of the fuel pressure line either. I changed it back to where it was and it still accelerates out of control.

Does it idle until you hit the brakes?

it will stay running until I hit the brakes. The brakes stop the wheels which stops the engine.

 

[Metalhead Matt]

Either there's a problem with the clutch or the gap in the carb is closing off too much.

 

[truggy83]

when I turn the trim on the transmittor to open the carb allittle bit that just increases the idle even more and makes the car take off even more

 

[charliejp]

I'm sorry for not going over this earlier. Lets try to get that linkage right. Turn on your TX and RX, 0 your trim then center the servo horn. With the trim zero out and the horn center, loosen the colars on the linkage next to the springs. Adjust the colars so that theres just a hair gap before they engage and tighten. This should get you to a good starting point to make any other adjustments. If your servo is still twitchy, you may need to replace it first. If that thing is sick it could be moving a little every time you turn it on.

 

[hamz9561]

If it's trying to take off at idle and dying when the brake is held, it sounds like the clutch to me. I would check that out also.