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TMaxx engine is driving me crazy, it won't idle

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TMaxx engine is driving me crazy, it won't idle

Old 02-19-2003, 02:48 AM
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Wookie
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Default TMaxx engine is driving me crazy, it won't idle

I've done everything I can think of to get it to idle. Here is what I've done so far:

-Leaned it out
-Richened it little
-Pulled the engine out, taken off the carb, cleaned it up and tightened it down (seals are fine)
-Taken off the starter and cleaned up the area around it and re-assembled
-Changed out the glow plugs.
-Changed the fuel line and pressure line
-Zip tied all of the ends for the fuel and pressure lines

On top of it not idling it doesn't like to start. I can turn it over for 10-15-20-30 seconds with not even a burp. Then other times it starts after about 1/2 a second.

I think it's an air leak but I've done everything to seal up the areas where air could come in.

Here is what the engine does:

When I get it started. It will rev really high when I get it started. Then I will take off for a short warm up and when I stop it will stay at a high rev. Then after about 5 seconds the revs will start to lower. Then they will go up and down for about 3 seconds then it will die. If I keep a little gas on it will continue running.

When starting it looks like it's getting too much fuel by looking at the exhaust. It also looks like the glow plug it fouling up a little based on the light on the starter, sometimes it's strong other times it dims out.

What it up with this thing?
Old 02-19-2003, 03:02 AM
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crash_me_over
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Default TMaxx engine is driving me crazy, it won't idle

What plug are you using? I would recommend using OS #3 or #8.

Try this:

1. Reset the needles back to factory settings....High speed needle should be at 4 turns out from stop.....low speed needle should be at 2 turns out from stop.

2. What fuel are you using? What percent of nitro? Is it fresh / new? If not....buy some fresh fuel.

3. Is your carburetor seated all the way down onto the engine? The small lock nut came loose on mine and caused similar problems as your having. Check for proper seating and tight nut.

4. Is the lid on your fuel tank sealed tight? To check for air leaks in the tank....remove both fuel lines...tank emptied....pinch the line going to the carb....now blow into the line removed from the exhaust. Listen for air leaking....or the ability to actually blow air through the fuel line.

5. Have you run the engine without an air filter....ever? If so...is it possible that you have dirt in the needles? Just a thought.

6. Is this a new rig? Is the clutch ok?

7. Have you adjusted the needles "ONLY AFTER" the engine is fully warmed up....then made the adjustments?

8. Changed out the fuel lines in the event of a pin hole leak?

Keep looking....if it's not a defective engine from the manufacturer....then it's something going on with one or more parts of all that makes the engine run and work. If you cannot find the problem...then give Traxxas a call. I hear they have excellent support and it's a toll free number.


Good Luck!
Old 02-19-2003, 03:14 AM
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Default TMaxx engine is driving me crazy, it won't idle

Answers to your questions:

1. I've readjusted back to the stock settings several times

2. Blue Thunder 20% Nitro

3. It is seated all the way down. I took it off, cleaned it and installed it. When I installed it I pushed down on it while tightening the lock nut. I also used lock tight on the lock nut.

4. I removed the tank from the truck and submerged it under water covering the fuel and pressure holes. No air leaks could be seen.

5. Never ran the truck with out an air filter, it's barely made it through the break in proceedure. (about 6 tanks through it now)

6. New rig, clutch seems to be fine.

7. Adjusted before, after, during, you name it.

8. Changed the fuel lines with no success today.

Got any other ideas?
Old 02-19-2003, 03:19 AM
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Default same thing here!

yeah im having the same problem with mine, sept i havent changed fuel line yet! will give that a try!
Old 02-19-2003, 03:22 AM
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Default TMaxx engine is driving me crazy, it won't idle

Which glow plug are you using? If it's the original....the Traxxas brand....switch to the OS brand. I went through 5 traxxas glow plugs on break in.....switched to my ole trusty OS # 8 and it still works.
Old 02-19-2003, 03:25 AM
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Default TMaxx engine is driving me crazy, it won't idle

I've got a McCoy MC59 in it right now.

When comparing it to the stock glow pluc with my other glow starter it's much brighter and is producing much more heat than the original.
Old 02-19-2003, 03:44 AM
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Default TMaxx engine is driving me crazy, it won't idle

WHAT HAPPENS IF I USE THE WRONG PLUG?

If you have used a plug that is too hot or too cold for your application, this will be revealed in one of two ways. If the plug is too hot, the engine may suffer from detonation, pre-ignition and high running temperatures. Detonation occurs when the fuel mixture explodes quickly rather than burns. You don't want this to happen because it can damage the engine. The telltale signs of detonation are a "miss" in the exhaust tone at high speeds and a pitting of the cylinder head around the glow plug and the top of the piston. Severe detonation can cause the coil element of the glow plug to come loose, and this can severely damage the engine. The primary cause of detonation, however, is excessive compression. Simply using a hot plug will not usually cause detonation, so don't be afraid to experiment. If you're using high-nitro fuel and have increased the compression by reducing head clearance, however, a hotter plug may just push the engine too far and cause damage. At the very least, an excessively hot plug will cause pre-ignition, in which the fuel mixture begins burning well before the piston reaches the top of the cylinder.

Using a plug that is too cold will result in a loss of acceleration and top speed and will cause poor engine idle. If the plug is much colder than it should be, you might notice an excessive raw-fuel discharge from the exhaust pipe, but don't confuse this with an excessively rich fuel mixture.


WHAT MAKES A GLOW PLUG HOTTER OR COLDER?

Many elements influence a glow plug's temperature range, but primary is the thickness, length and composition of the wire used to form the coil. It will be impossible to find out anything about the composition of the wire because most manufacturers keep it a secret, but the wire can certainly be measured. Other factors that affect a glow plug's temperature include the size of the hole in which the wire is installed, the type of plating used on the glow-plug housing and the material the glow plug's housing is made of.

http://www.rcnitro.com/rn/articles/glowplugs.asp
Old 02-19-2003, 03:53 AM
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Default TMaxx engine is driving me crazy, it won't idle

I am not totally sure what could be wrong with yours, but I will tell you what I did with mine. Maybe it will help.

After my break in runs, and I was done with that I started to tune my engine for speed and consistency. I leaned it out, and got it to where I thought it should be. Adjusted the LSN and the idle screw. I thought I was set, but I found out later I wasn't.

I went home that night, and had used the last of my fuel. I bought a different brand, and set up to idle a tank of the new fuel per the many suggestions from RCU users. When I started the engine, it idled fine. Then it started to idle high, then idle low, then high, then low and finally die. I was very frustrated. I was meeting up with Crash_Me_Over the next day, so said screw it and went in for the night.

The next day I met up with CMO and he happened to remember the stock needle settings. I returned them to the stock positions. on the HSN turn clockwise to lean it until you feel it get a bit tight. Don't go too tight you might hurt something. Once it's a bit tight turn it 4 complete turns(counter clockwise) out aka richen. This is the stock setting for the HSN. The LSN should be returned to flush.

I warmed the engine up and did a few high speed runs. When I got up to full throttle the engine would start to cut out. According to the manual this is supposedly too rich, but on the contrary CMO told me it was actually too lean. So I richened up the mixture, slowly 1/8th of a turn ,with a couple of high speed runs between each adjustment, until it stopped cutting out on me at high speeds. I like to run my engine more rich, for longer engine life. So I richened it up even more just to make sure there was plenty of lubrication.

So then I adjusted the LSN by using the recommended pinch test. and then adjusted the idle speed.

It's running great now, just like it should. I hope this helps, I have seen others having the same problem, so I wonder if the factory settings for the 2.5 are too lean for cold weather break ins.

Good Luck
Old 02-19-2003, 04:01 AM
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Default TMaxx engine is driving me crazy, it won't idle

Originally posted by Dlock
It's running great now, just like it should. I hope this helps, I have seen others having the same problem, so I wonder if the factory settings for the 2.5 are too lean for cold weather break ins.

Good Luck

Dlock has hit the nail on the head with the temps playing a factor on where "YOUR" needle settings will be. The colder it is outside...the need for a richer setting is important. In our winter time temps...we set the needles richer for better runs.....and this is somewhat covered in your manual.


Good job Dlock!
Old 02-19-2003, 04:07 AM
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Default TMaxx engine is driving me crazy, it won't idle

Now THIS was a HELLA GOOD thread.. full of consolidated information, helps solve problems, interesting to read.

THANKS!

My thoughts

Just because it sputters out fuel when it starts doesnt mean its rich.. could be that the fuel got there just because you were pulling on it so many times and the fuel just leaked thru the engine.
"Engine revvs up then cuts out"... CLASSIC sign of "lack of fuel"..

I cant think of anything that could cause it seeing that you did all this work on it.

Dont give up.. I'm sure its something small and stupid!

Take a break and go back to it.. I know its frustrating.. but when it runs fine.. you will be even happier

Only after you go through frustration can you enjoy the true effects of success
Sorry about the lecture..lol
-ram
Old 02-19-2003, 12:16 PM
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Default TMaxx engine is driving me crazy, it won't idle

Ok, I stopped reading around the 4th post cause I gtg, but my buggy had the same trouble. It was a pain to get it started, and it would remain idleing for me. To get it to start better I heated it to about 80-100 then it would start first pull. After it was running I would drive around a bit and it would just stall. Start it up drive 5 feet come to a stop then it would STALL......

My idle screw needed to be ajusted runs great now.... thank god.
Old 02-22-2003, 01:37 PM
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Default TMaxx engine is driving me crazy, it won't idle

HEY WOOKIE GLAD TO SEE ANOTHER OREGONIAN IN THE CHATTS

TELL YOU WHAT I HAVE A FREIND THAT IS EXCELLENT WITH THE TUNING AND CONFIGURING OF ENGINES EMAIL ME IF YOU WOULD LIKE TO DISCUSS THIS FURTHER

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