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TRX 3.3 Won't start

Old 06-05-2022, 05:32 PM
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Default TRX 3.3 Won't start

Bought a new Revo 3.3 cause I wanted to give Nitro a try so I'm pretty new to this. I followed the break in process to the letter. Everything seemed good, motor started performing better over the course though you could tell it was running rich. I did have to richen the LSN as it was idling way too high and taking off on it's own. I checked the idle and it was around .7mm, basically a paper clip end will fit in there but not much else. I also reset the HSN per the manual 4 turns out from fully closed just to be safe. I took it to the park today to try and tune it and I was slowly leaning the HSN out an hour at a time and making a few passes to see how it ran. I didn't turn it maybe 1/4 to 1/2 a turn when I pulled up to check it and it just died. I also noticed some greyish white smoke coming from where the glow plug is. Very very faint, not smoking per se. Could not get it started again after that. Took it home, started checking things, tested the glow plug and it does not glow. This was a brand new glow plug I put in before this run. I chucked the one from the break in as the Traxxas manual said it would be pretty fowled and it was when I took it out. I also noticed when I went to take out the new glow plug that it was pretty lose and I always tighten plugs just a bit past snug. I'm trying to figure out if this was maybe a fluke and just a bad plug or if it's something more serious. I forgot my temp gun, I was just gonna run the one tank and then run home and grab it so I didn't get far in the tuning process however I used some water and it wasn't instantly evaporating but it sizzled for a few seconds and then evaporated. I don't think it was overheating. I just can't figure out the smoke unless the glow plug came loose and it just lost compression?
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Old 06-06-2022, 02:28 PM
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if the glow plug was loose it would shut off.. replace glow plug and go again..

If glow plug comes loose again you may have a dated head
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Old 06-06-2022, 06:56 PM
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I went to my LHS and bought 5 new glow plugs just so I have some spares. Both my LHS and Traxxas said it sounded like it was running too rich. I changed glow plugs, reset to traxxas factory settings on the HSN and LSN. Tried to start it and got it to briefly start once, died and tried to start it again and it turned over and just would not start. Traxxas manual says 4 turns out from closed on HSN and LSN flush with washer. I had to go to 6 full turns from closed and maybe .5mm past flush on the LSN to get it to run somewhat decently and actually start. At around 4 1/2-5 full turns it would run up to second gear and just stutter and/or die going into second. Made all adjustments an hour or a click at a time. As I richened the HSN I was able to lean out the LSN a little bit so it's closer to factory setting but still on the rich side from that. I feel like it's still rich, back of the car up to the shocks is very oily and there are drip marks on the pavement where the exhaust drips. I get lots of blue smoke past 1/4 throttle and then once it gets to about where it wants to shift into second the smoke tapers off. LSN may still be a bit rich. Only thing odd I noticed is that turning the needle for the HSN also turns the bronze nut underneath a little.

I now definitely think it overheated and probably cooked the glow plug. I think it was running rich on the bottom somewhat and super lean on top. Break in was mostly 1/4 to 1/2 throttle 2-3 second runs and even going to WOT was very brief really. I wonder if there's perhaps something wrong with the HSN?

Also for the glow plug being loose, I don't know if overheating could have caused that but the plug was dead. I was using the supplied wrench and maybe I didn't torque it on enough when I replaced it? I used my 8mm socket and driver and torqued a little past snug with the new one and it seemed to still be on there tight after a full tank run.
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Old 06-14-2022, 03:37 PM
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I think I'm done with this. I've spent hours trying to get this thing to just run stable going lean, going rich, starting over from factory settings. I've watched a ton of videos on tuning and 99% sure I'm, not doing anything wrong. I just can't find anything that works.

The idle screw does not change my idle speed at all, it just stays the same until I screw it in and it can't stay running. I've set it with feeler gauges to .7-1mm tried .7-.8-.9-1mm. Only way I can control my idle speed is with the LSN. The HSN is a turn and a half out from factory settings. If I start going in from that it runs hot and starts blowing glow plugs. It won't shift at WOT it just revs up and stays there, I have to slowly give it throttle through the powerband. This seemingly gets better if I start richening the HSN to a point. Checked throttle servo and 100% throttle is carb fully open and flush with the carb intake. Everything points to it running too lean, the tailpipe and the mess coming out the back say's waaaaay too rich and I'm blowing plugs which traxxas says means it's too rich but it will hit 300 F and smoke after 2-3 WOT passes if I start leaning it out. I keep trying to richen it but I don't want to just keep going and going. Conversely, leaning it out like I said blows plugs and I don't want to buy glow plugs every 2 tanks which is about what it's averaging. I make very small changes, 1/8-1/16th a turn at a time and do a couple passes.

forgot to add it seems to want to move on it's own and If I lift the truck the wheels will spin like crazy and the engine revs up pretty good. I have to richen the LSN so it doesn't do that because the idle screw does not change the idle speed at all.

Also this was a brand new truck and I did the break in process with the Traxxas factory settings which seem to be too lean but are actually supposed to be very very rich. I've also only used the Traxxas top fuel, 20% to break it in plus 5 more tanks and now I switched to 33%.
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Old 06-14-2022, 04:24 PM
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Im no expert by any means but I hate to see someone about to give up. You say the idle screw won't adjust the idle, is your throttle linkage in a bind? The last time I needed to lower my idle, I didn't have any slack in the linkage so when I made the adjustment on the carb the linkage wasn't letting the slide actually close further and I didn't see any difference.
I had a traxxas with a 2.5 when I was young and we had so much trouble tuning it. After some research, I blame it on the traxxas fuel. I don't see any other reason it should have been so inconsistent. I've found quite a few people on the internet saying it makes motors harder to tune and run hotter compared to other fuels.
I've been using VP fuel in my most recent car and its been great. I spend a couple of minutes getting the tune close when I first start my day and usually never touch it again unless the temp swings a lot. I started out running their high oil 20% and ended up switching to their 30% lower oil content fuel. It ran great on both, I had no problems tuning for the switch either.
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Old 06-14-2022, 05:24 PM
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It adjusts the slide inside the carb, linkage isn't in a bind, but both in terms of the motor revs and the truck trying to move forward on it's own it does absolutely nothing. Tried three full turns, going to extremes trying to get it to do something and revs never change truck will still creep forwards but then it will slowly die. It's my first nitro, I don't know how much is too much fuel out of the exhaust but the entire back end of the car is completely covered in unburnt fuel, Literally from the back of the fuel tank all the way to the plastic chrome bumper. That seems excessive to me like it's running stupid rich. If I start leaning it out from factory settings it will just start dying if you give it any throttle. I've only really adjusted the LSN to get the idle right and to tune the acceleration from a dead stop. Even that though seems to drift. I'll get it where it sounds good, good idle speed, doesn't roll forwards and then a few passes it will bump up in idle speed and start rolling or it will sound like it developed a deviated septum, idle will start dropping and it will start dying. I honestly think something is wrong with the engine if conventional wisdom is factory settings are supposed to be rich for break in and I'm having to go the opposite way.

Traxxas support was pretty terrible. First guy asked my name and then just put the call on hold indefinitely after getting my name, waited like 5-6 minutes. Second guy at least sent me a replacement glow plug and said it sounded rich and just hung up. Fuel was suggested to me by my LHS, I figured Traxxas truck, Traxxas fuel should work. I've heard bad stuff about them and the only reason I went with them was I wanted a truck because I run mostly on grass and buggies from what I've seen and heard just don't run good on grass. More for sandy or dirt tracks. Maybe I shoulda went HPI but good luck finding it locally and I have yet to find someone who retails them online.
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Old 06-14-2022, 05:55 PM
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I also want to add that the glow plugs that have gone bad don't look blackened or damaged really. One was a bit more of a bronzed color but it actually lasted like 5 tanks and the one from when I broke the motor in was blackened pretty bad. It didn't stop working I just replaced it cause the manual suggested to.
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Old 06-14-2022, 06:00 PM
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I would definitely avoid taking big swings at anything, even if it is just your idle screw. Careful doing that, you'll really end up in left field.
Something is keeping the carb from sliding more towards closed though if you really put that many turns on it and nothing happened. You're not directly moving the carb slide with that screw, you're setting an end point. In my case, a collar on the throttle linkage didn't have enough gap and as I closed the carb gap I put the linkage in a bind not allowing the slide to go to its endpoint.
Try some different fuel if you get a chance
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Old 06-14-2022, 06:27 PM
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It's moving, I can take the air filter off and close it if I want to and watch it slowly close. No bind. It still doesn't affect motor RPM literally at all. I'm actually starting to think there's some sort of air leak or compression leak. Could be fuel and I'll try to order some VP 30% to test it out. The fact that there's so much fuel residue all over the car, not just out of the exhaust and having such a hard time tuning, maybe the bearings are shot or there's a leak somewhere? For a new engine that's stupid but things happen and it wouldn't surprise me.

Also big difference between taking big blind swings and wanting to test that turning something to the extreme does absolutely nothing. If I know I turned it 3 full turns I can always turn it back. I wanted it to die and/or I wanted it to rev up and start moving on it's own etc... Sadly it did neither.
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Old 06-14-2022, 09:42 PM
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If you had the filter off and watched the carb shut all the way and it was still running, you have an air leak. Follow the residue that didnt come out of the exhaust and you'll find it
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Old 06-15-2022, 03:23 PM
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I've never closed it while it was running, I've never tried anyways. I have closed it while it was off and I was looking down the carb though so I know it's not binding was what I meant.

Tried it a bit today. Feels like I'm getting closer but I think it's the fuel. I'm gonna try to get it to run on the rest of this traxxas top fuel and then switch to something else. I stand corrected, the idle speed screw is affecting the idle speed but it's very very minute. Also it will be seemingly running good and after a high speed pass I will bring it back and it will just die for no reason. Maybe the fuel causing it.

Prolly the only nitro I will ever buy. With as many issues as this thing has had it's too much a pita to just go out and have some fun. Wouldn't be bad if I could just get it dialed in and make a change here and there but this is just constantly having to play with the needles to keep it running. Maybe I picked a crappy starter truck and starter fuel but really electric is just so much easier. I like my 1/5 scale stuff and I've been eying a gas powered Losi DBXL or 5ive-T so I might venture into that territory at some point for my loud fuel powered RC fix.
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Old 06-15-2022, 03:30 PM
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If you have fuel all over the car you have a leak some where, until you find where it is leaking it will never run right... small leaks cause the world of problems

What you are describing is growing pains, same as I had back when I started wth a Tmaxx.. these things are beginner or intro into nitro cars. you learn on these then progress to higher end stuff. But nitro and the all idiosyncrasies that come with it is not for everyone... Takes allot of time and patience

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Old 06-15-2022, 04:32 PM
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I guess you could call it idiosyncrasies but It's the inconsistency that I can't deal with. Like If I have to tune something but I make progress I can mess with it all day as long as I can clearly see I'm making progress or regressing.

Should my car have unburnt fuel, like I can run my finger along the bumper, exhaust, pipe, fuel tank, rear shocks and come away with a finger covered in fuel. That's how it is every time I run it. If I run it in the grass, grass and fuel are caked onto the rear bumper and the rear of the body. Lean or rich it does this.

Upon acceleration I get a huge cloud of blue smoke no matter the LSN setting. Way more than I've seen in most video's and nothing has changed that. I just do the pinch test to set the LSN. it revs up and dies within 2-3 seconds. It will shift into second but if it's WOT it instantly goes to full rev. HSN seems right, I get a nice thin trail of blue smoke. Engine doesn't bog down and temp seems ok. I had it like that last time I took it to the park and blew a glow plug in a half a tank. Had it like that this time and it started dying on me when it would idle after running today. Idle would slowly go down and then dead. Have to blip the throttle to keep it going. Inconsistent.
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Old 06-15-2022, 06:33 PM
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Fuel all over your car is not normal, on your fuel tank is even weird . Is the tank sealing properly.. lots of things to check.. my advise is to clean off all fuel on the car.. brake cleaner and compressor.. then run it again making sure to look fort hat leak. If you have a leak you will never get it running.. I mean never
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Old 06-16-2022, 01:12 PM
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I use simple green, works good and safe on plastics from what I've seen. Cuts through fuel and oil just smells bad to me. Tank seems to be sealing fine, O-ring on the gas cap seals when pressed down. Doesn't look like it's leaking from there. I wondered if maybe from the head or the exhaust because the concentration seems to be on top of the exhaust pipe coming out the back of the engine. I'll check bolts and make sure they're all tightened down good. I'll try to clean it and look for any leaks. There's fuel residue all the way up to the wires running to the engine that go along the back of the fuel tank and also residue on the tank itself. It's mostly concentrated it seems like though from engine back. I'll just try to check and see if there's a leak.
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