REVO expert tuner needed badly !!!

[dgsmooth]

cheers all - i am in dire need of some help with my revo 3.3. i had it running a number of times over the last couple weeks and have been working on getting it tuned just right. went to start it today and it won't start. i set the high, low and idle screws all back to factory break in settings. both lights on the easy start light up nice and bright and its fully charged etc. it will start and run for 2 seconds then quit. if i hit the button again it will start instantly again but will always stall again. if i use the throttle and rev it up once it fires it will respond really well and the engine will increase according to the throttle i'm giving it but it will still stall no matter what i do. i had the wheels of the ground incase it was the clutch or something, still stalls. if i have it off the ground, use the easy start and throttle and get it reving up with wheels spinning, still stalls. according to the traxxas knowledge center it could be a number of things, but none really make sense. i don't thinks its the clutch or bearing as it starts and revs up. i don't think its the mixture screws etc because it starts very well and if i move the low mixture screw either direction a 1/4 turn it won't fire-up nearly as easily, leading me to believe the mixture screws are good, or at least close enough to perfect that it should run. for the 'starts but then stalls' section it also lists glow plug as possible cause but i thought the glow plug was just to get it running as once you remove the easy start the glow plug isn't doing anything anyway ????? i'm lost......i just got this thing and now i'm really getting frusterated. it was running so good but today this happens. i'm a HD mechanic by trade so i'm doing my best to not get mad and just use logic to go through and isolate the problem but having no luck. is my engine toast? what could have happened since the other day that it won't run now? the only thing i can think is maybe some dirt or debris got in somewhere? how sensitive are these things to fuel pressure? i have fuel dripping out the exhaust, but i'm not sure if it thats from being to rich or just from trying to start it over and over again for 20 min. the thing is basically operating temperature from running 2 seconds at a time 2 hundred times, so it should just run. i tried going a little on the lean side just to get it to run but no matter what it won't run for more than 2 seconds. sorry for the long read but i am desperate and my pride won't allow me to drop it off somewhere to be fixed and me not understand the problem, especially now that i know i can't figure out myself. the person who helps me out and figures this out will be me new personal r/c hero and i'll be spreading positive accolades around town with his name attached for a long time.......thanks to anybody who can give even a slight help in the right (or any) direction. cheerio, dennis.

 

[GusMax86]

Age?

How many gallons have been through the engine?

 

[RevoAxial28RR]

First thing i would sugest is to put a new glow plug in it, the glow plug is what causes combution, its keept at opperating temp after you remove the starter by the heat of the combustion, so if its worn out then it won't stay running. Second thing to fidget with is your low speed neddle, if it starts and stalls like that, its probibly too rich, causing it to kind of flood the motor with too much fuel expecialy if your getting alot of fuel in your exaust. Nitro motors are sensitive to the slighest air temp and humidity changes. Also you may want to check to make sure all your fuel and pressure lines are good and your tank lid doesn't leak air out of the tank. You'll feel a HUGE difference when you "blow" a motor, you'll know it for sure. This may be a dumb suggestion if you already thought if it, but make sure you idle squrew is set open enough. But like I said first, your glow plug is the first thing to check and most likley the problem. I know my 3.3 fried glow plugs like chicken wings, where as my .12 os tz 5 goes forever and a day on a single plug. Try a hotter plug if you can too.

 

[Rolex]

Yup, new glow plug for starters. The glow plug gets heated up by the igniter, then when the engine starts, the constant compression and ignition keeps the filament hot enough to ignite the next cycle.
As for your tuning, if you're spitting oil, you're too rich. Set both needles to factory, then lean both of them by about 1/4 turn. Start the engine. If it starts and wants to stall, you might want to set your throttle trim tab up slightly. Let it idle till it starts to warm up. When you blip the throttle enough to engage the clutch, make note of if it seems sluggish or if it responds. If it's sluggish taking off, lean the LSN another 1/8 of a turn. When it takes off nicely, lean your HSN for WOT but make sure you keep a nice trail of blue smoke. Check your temps.
Once the idle and LSN are set correctly, you'll still need to make regular slight adjustments on the HSN for ambient temps and humidity.
Keep us posted.

 

[dgsmooth]

well thats sort of what i was thinking from other advice i found. i have 'the real macoy' glow plugs. where i bought them they told me mc8 in the summer, and mc59, which is hotter, in the fall. i got two of both and have tried the hotter one but same thing. actuallt when i first put the hotter one in it ran for probably 20 seconds, then stalled. when i re-started maybe 5-10 sec, then 2 again over and over.......if i turn the low speed/idle mixture screw in a smidge then it won't even run for the 2 seconds???? everything is at factory settings from traxxas, .7-1 mm on idle screw, 1.5 turns out on low mixture and 4 turns out on high mixture. if i move the low mixture screw either direction 1/4 turn then it won't fire at all. i removed one of the starter motor wires and used a jumper wire between, then i start it and remove the jumper wire and then keep on the easy start trigger to keep the glow plug going - if i do this then it will stay running, but when i release, out it goes. thanks for the direction mate, it sure seems like a glow plug issue but it ran so well the other day.......this is killine me...........

 

[RevoAxial28RR]

i had a macoy plug once, my 3.3 never liked it, hard to start and stalled all the time fouled out the first day i ran it. the traxxas plug always ran better in it, but hey some people love macoy plugs, i've always had good experience with O.S. but i use turbo plugs

 

[Captain Chaos]

The 3.3 likes a long reach plug.Traxxas 3232X(I think), OS LC3,LC4,and I have had great luck with the OS A3 that is not a long reach plug.

 

[Runaway Jim]

I read through the threads and since no one has mentioned it yet, I figured it wouldn't hurt to ask... What does it sound like when it is running? Does it sound normal or does it sound like there's something else going on in there? I only bring this up because I had a 3.3 that was defective from the get go and it sounded like someone dropped a box of plastic forks in it from the get go. Also, have you checked to make sure that everything is tightened really well? The cooling head screws get lose every now and then and also the screw/nut holding the carb on should be checked every now and then for tightness. If it doesn't sound good when it's running, bust into that thing and see what the piston head, connecting rod and sleeve look like. If you notice any pitting on any of them you may have got something in the engine that caused some damage which could really hurt the regularly high compression level of the engine...

 

[Rolex]

Post #5 said it all. If you can keep it running with an igniter on the glow plug, then you are running too rich. Try leaning the LSN slowly while spinning the starter till it will stay running without the jumper. You're flooding it on the low end, it seems.

 

[dgsmooth]

okay, thanks for the help, i got it running, but something is still out. it seems to idle high and run-on, like when you let of the throttle to coast the engine takes a second ot two to come down. and when i first crack the throttle from a slow roll it bogs for a second before taking off, even though there is a trail of blue smoke behind it once it takes of.....it got too late here and too loud so i had to come in. for tomorrow i'm thinking get in running again, then maybe lean the LSN a smidge more? but leaning it would seem to make the racing at idle and run-on even worse.......or do i need to richen to LSN to bring the idle down? ciao, dgsmooth.

 

[MrClean]

Your idle should be the last thing you set. If you are bogging down from a dead stop, then your LSN is on the rich side. Start leaning it out 1/16 of a turn at a time until you get a decent launch without the bogging. If you have a good smoke trail now, then setting the LSN isn't going to affect that. Then you can adjust the idle setting.

Do you have a temp gun? If not, you really should consider getting one. It can also help with tuning as well as ensuring you're not leaning the engine too much.

 

[Rolex]

If you're sluggish getting going once the engine is up to temp, you need to lean the LSN a little more. Keep a close eye on the temps because if you go too lean it will heat up quick. Leaning it will probably mean lowering the idle also. Make sure the throttle trim is turned down to zero, and apply your brake when you adjust it, then you won't be stalling when you go to stop it.

EDIT: MrClean posted while I was still typing, but there you have the second opinion.

 

[dgsmooth]

yeah we have a temp gun at work.......what kind of temperature is a normal operating temp and what is getting too hot? how much does ambient temperature affect that do you think......be about 20 deg.cel here tomorrow.

 

[Captain Chaos]

I had a 3.3 that was screwed from new.Acted eracticly after break in.Sent it back to Traxxas and they rebuilt it noting a bad bearing.Greatr customer service.It made some weird clattering noised also.You can have a lean bog if the low speed is to lean.I was running my ls to lean and my hs to rich.Now that I have fatted the l end and leaned the high end the engines are working much better.You don't want to get it to hot early in the break in.Plenty of smoke,tank one 180,tank two 190,tank 3 200 tank 4 210 you get it,stay below 230 until after 6-7 tanks.Maxx is like 270-280 after break in.

I am not an expert so take this advise at your own risk

I am getting it down now but I have enough paper weights to survive a hurricane during the learning curve.

 

[MrClean]

If you're sluggish getting going once the engine is up to temp, you need to lean the LSN a little more. Keep a close eye on the temps because if you go too lean it will heat up quick. Leaning it will probably mean lowering the idle also. Make sure the throttle trim is turned down to zero, and apply your brake when you adjust it, then you won't be stalling when you go to stop it.

EDIT: MrClean posted while I was still typing, but there you have the second opinion.

I noticed my comment was similar to yours, Grasshopper has paid attention Master.

yeah we have a temp gun at work.......what kind of temperature is a normal operating temp and what is getting too hot? how much does ambient temperature affect that do you think......be about 20 deg.cel here tomorrow.

Weather period plays a big part in tuning a nitro rig. Different conditions require a different fuel/air ratio. Most times it's just a little tweak here and there of the HSN (once a motor is properly tuned). My Revo 3.3 (and most other TRX3.3 motors in general) likes to run hotter than other motors, it screams right along at 270-290F........oops, sorry - 130-140C... You don't want to let it go over 149C for very long. If it does get that warm, don't start making huge adjustments to your needles, just keep tweaking them a little at a time. Running it a little hot for a short period of time won't kill the motor right away.

 

[Captain Chaos]

Good advice Mr. Clean now go to bed:beard:...LOL .

 

[MrClean]

Good advice Mr. Clean now go to bed:beard:...LOL .

.........no way, the clowns are waiting

Where did you get that smilie from? I can't tell if it has hair on it's head, but the goatee is correct. I think Woodie made a smilie just for me.

 

[dgsmooth]

well i got running this morning, it would cut out for a second when accelerating and at speed, so i richened the high needle a bit and that fixed that. still seems to hesitate on launch still, so i'm slowly leaning that down. is it possible to overheat the engine at an idle? if you lean the LSN too much will it overheat just idleing or just idle too high? it seems if i get it running decent then shut it off i have to re-fiddle with it to get it going again. thanks for all the good advice, i'm getting there........i think i had the high speed needle to lean and the low too rich. i used the temp gun and got 269.F, and its only like 15 deg.c outside right now. i'll try a little richer on the high and a little leaner on the low, then worry about idle speed last right? stay tuned, i can feel the 'runs awsome!' post coming.............

 

[dgsmooth]

the 'runs awsome' post !!!

anyways i think i found the problem. somebody on another post had mentioned an internal leak in the fuel tank, as this would suck in air at times and lean the mixture, but mostly it would explain the inconsistent performance. i was pretty sure the tank was okay as its almost new, so i started checking other things - low and behold i found the carburetor was loose, almost came out in my hand when i wiggled the air cleaner tube off. the o-ring looked good and everything so i made sure it was pushed all the way in and tightened it up. tried again the next day and fired up immediety - and now it responds to tuning as it should. i was way rich from where i had it, so with some high-speed passes i got the HSM set right, then found the LSM was rich as it would run-on for like 5 seconds when i did the pinch test. leaned that down a little so it would launch nice without hesitating, that raised the idle slightly so lastly i lowered the idle a bit - perfect. that was yesterday. this morning i went to the local track - put in the starter and fired right up. ran perfect, idles beautifully. before it would 'run-on' after you let off the throttle to coast from the air leak leaning in but now it runs so perfect. did a couple laps and wow - its so smooth, the throttle and brakes are so sensitive and responsive, and the suspension! its like art in motion........thanks to everybody who posted something for me - every post helps because you have to go through one step to get to the next. with all the experience and know-how of everybody that reads these forums, anything is possible and nothing can't be solved. salutations to everybody who trys to help somebody else out - i hope i'll be able to help out somebody else, when you feel such appreciation for something the most instinctive way to make yourself feel you've properly thanked is to pass on the good nature to somebody else and help spread goodness. cheers.

 

[MrClean]

Glad to hear you found the problem, makes you feel good that it was something actually wrong and not a 'user error' You can also use some RTV to seal around the carb to ensure it doesn't leak again. There are a few threads with pics on how to do this. It's a good off season project.

My Revo loves to run around 270, for some engines that's a little on the warm side, but mine seems to like it the 260-280 zone. If I try to adjust the motor any richer, it starts to get sluggish.

Good luck and happy bashing!!