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Old 02-18-2012, 05:40 PM   #1
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Default Problems with hpi rs4 3 rtr

I am trying to help out a friend who just bought a barely used hpi rs4 3 rtr with the nitro star .15fe. The guy he bought it from had barely used it. The bottom of the chassis looked brand new and he said it had just been finished breaking it in.

The problem I am having is no matter how I tune it I cant keep it idling. It doesn't matter if it is running very rich or lean. I can do full throttle all day long and have no problems but as soon as I stop it will idle for 10-20 seconds then die. I have reset it back to factory settings so many times I have lost count and no matter what I do it will not idle correctly and stay idling. It is also having issues starting, Usually I have to put it at half to full throttle just to get it to start. I have to prime it 4 or 5 times every time i start it even if the engine is warm and just died 10 seconds before.

I have tried 3 brand new glow plugs and none of them seemed to change a thing at all. The carb is a rotary carb with only a idle gap and HSN. It does not have a LSN to adjust.

So am I doing something wrong tuning this or is there another problem causing me and him these headaches?

Thanks for all replies.
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Old 02-18-2012, 06:04 PM   #2
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You need to adjust the idle screw.

http://www.hpiracing.com/manuals/pdf/10053.pdf
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Old 02-18-2012, 06:15 PM   #3
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I have tried adjusting it and it seems to make no difference what so ever. The manual link you posted is to a different version of his car. In the box from his car there was a receipt for the car itself dated 4/14/2003. I think the car sat untouched for several years
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Old 02-18-2012, 07:16 PM   #4
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I would try starting the engine with the radio/car off with the air filter removed, that way I could see how far the carburetor is open and make my adjustments again once the engine is started. I make sure I don't run the car with the air filter removed.

Once it's idling with the radio/car off, turn on the radio and the car and see what happens.
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Old 02-18-2012, 08:54 PM   #5
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Originally Posted by Bubblehead View Post
I would try starting the engine with the radio/car off with the air filter removed, that way I could see how far the carburetor is open and make my adjustments again once the engine is started. I make sure I don't run the car with the air filter removed.

Once it's idling with the radio/car off, turn on the radio and the car and see what happens.
I just tried this and it still won't idle. It will idle a little longer (roughly 30-40 seconds) but it will still die.

Anything else I can try?
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Old 02-18-2012, 09:34 PM   #6
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Do you see air bubbles in the fuel line and how old is your fuel?

Check the fuel line for any holes make sure the pressure line is not blocked and the lid of the fuel tank has a good seal. Check the motor for leaks, (motor head, back plate, carburetor is not loose)
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Old 02-18-2012, 09:37 PM   #7
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Have you changed the fuel lines? If the car has been sitting that long the fuel lines are probably shot, any cracks or holes would make idling tough. I would also check the fuel tank.

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Old 02-18-2012, 11:16 PM   #8
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This maybe crazy as i dont know all there is to know about nitro engines but my car was doing something similar and it ended up being a bad glow plug
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Old 02-19-2012, 12:17 AM   #9
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As soon as he got the car we replaced the lines with brand new lines, The fuel is brand new as of a week ago, and we checked the tank for air leaks(and cleaned it out completely before running it), I am probably going to pull the motor out tomorrow and check it for leaks as I have no other idea of what could be causing it.

The funny this is the tank seals fine but it seems like around a half tank it will get some bubbles in the line and die but after that it doesn't do it again till empty. It doesn't have air in the lines when it is idling just always at half tank. The weird thing is the car runs perfect as long as you don't let it sit and idle. it has good power and it doesn't overheat or anything like that. it just wont idle no matter what we do.
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Old 02-19-2012, 02:24 AM   #10
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Quote:
Originally Posted by AADrcw View Post
As soon as he got the car we replaced the lines with brand new lines, The fuel is brand new as of a week ago, and we checked the tank for air leaks(and cleaned it out completely before running it), I am probably going to pull the motor out tomorrow and check it for leaks as I have no other idea of what could be causing it.

The funny this is the tank seals fine but it seems like around a half tank it will get some bubbles in the line and die but after that it doesn't do it again till empty. It doesn't have air in the lines when it is idling just always at half tank. The weird thing is the car runs perfect as long as you don't let it sit and idle. it has good power and it doesn't overheat or anything like that. it just wont idle no matter what we do.
AADrcw,

When you immediately try to start it again, does it start first time?
If so, it would seem your bottom LSN needle is a little rich, regardless, this is normal, a nitro engine is normally tuned a little rich on the bottom as to lubricate the engine off throttle while at full throttle it will be lean and in need of lubrication

The more you attempt to tune the engine to achieve a permanent idle, you are very likely to run into problems when running thec ar under load and a throttle after run is what I expect you to have to deal with next.

By opening the idle gap too far and allowing too much air in during a rich idle mixture will pose other problems when you lean out the engine down a long straight

Ideally, you should clear the crank after 4-5 seconds while idling to keep the engine crank from flooding.
You should also check your clutch.
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Old 02-19-2012, 04:29 AM   #11
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Will the engine idle if you have the car on a car stand?

Is this the engine page(s) 31-34?: http://www.hpiracing.com/instruction...t-n3typess.htm
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Old 02-19-2012, 01:45 PM   #12
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Quote:
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AADrcw,

When you immediately try to start it again, does it start first time?
If so, it would seem your bottom LSN needle is a little rich, regardless, this is normal, a nitro engine is normally tuned a little rich on the bottom as to lubricate the engine off throttle while at full throttle it will be lean and in need of lubrication

The more you attempt to tune the engine to achieve a permanent idle, you are very likely to run into problems when running thec ar under load and a throttle after run is what I expect you to have to deal with next.

By opening the idle gap too far and allowing too much air in during a rich idle mixture will pose other problems when you lean out the engine down a long straight

Ideally, you should clear the crank after 4-5 seconds while idling to keep the engine crank from flooding.
You should also check your clutch.
If I try to start it right after it dies it will not restart without priming it again. also it does not have a LSN at all, just a HSN and a idle gap screw

bubblehead it will still die if it is on a stand or on the wheels
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Old 02-19-2012, 01:48 PM   #13
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bubblehead I tried to post a link to the engine but I do not have enough posts yet to do that. it is the 15fe with the purple cooling head
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Old 02-19-2012, 02:31 PM   #14
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What type of plug are you using? I would try O.S. #6 or McCoy MC59
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Old 02-19-2012, 03:03 PM   #15
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we just put a brand new mc59 in it yesterday. we have also tried 2 new mc9 plugs and nothing changed with any of the plugs
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