• Welcome to RCTalk! 🚀

    Join the #1 RC community where hobbyists connect, share, and get expert advice on RC cars, trucks, boats, drones, and more!

    • ✓ Friendly & passionate RC enthusiasts
    • ✓ RC tips & troubleshooting
    • ✓ Buy, sell & trade RC gear
    • ✓ Share builds & upgrades

3.3 Engine Troubles

This site may earn a commission from merchant affiliate
links, including eBay, Amazon, and others.
N

newfienew

RCTalk Basher
Messages
46
Reaction score
1
Points
0
RC Driving Style
I have a 3.3 engine in my Tmaxx. It will start and idle perfectly, and run at half throttle with little to no problem. However, when I hit the throttle full it will cough, sputter, backfire and blow unburned fuel from the exhaust. If I let off on the gas it will sometimes idle again and other times I may just have to restart it. It burns a lot of fuel as well. I have reset all needles to factory settings, thus it is not over rich. As well I am not new at tuning the 3.3 engine. I've done plenty of that including my (working perfectly) revo 3.3. Any advise would be appreciated

Newfienew
 
Factory settings are only for break in. You need to tune it for performance, while making sure it doesn't overheat. I'd change the glow plug and start slowly leaning it out. One hour at a time. Watch your temps. You'll want them between 240 and 270, give or take.
 
I have tuned nitro engines plenty in the past. I'n not a novice to tuning. This seems to be a different issue!!! It only happens at full throttle. COughs, sputters and backfires while spewing some unburned fuel from the exhaust.

Any other suggestions
 
I was having a similar problem with my 3.3 slayer, and it turned out just being a bad glow plug. I changed the plug, and it works perfectly now
 
it's too rich, the popping and backfiring you are hearing is called a flame out. this is caused by either a fouled plug or an INCREDIBLY rich tune. get it as tuned as you can, replace the plug, and make final adjustments.
 
I have it tuned ok as it ran perfectly 10 minutes before the popping problem. As for the glow plug, I thought that glow plugs were only used for starting the engine and then had no other function???? Am I wrong on that point???

Thanks Guys

Newfienew
 
I don't understand how they do this without a constant power supply but the glow plug keeps the engine running by ignighting the fuel. I'm sure someone else will come in and explain it better
 
The compression of the engine keeps the plug glowing. Change the plug and tune it. Have your temp gauge handy. You'll probably have to open the lsn a little as needed as you lean the hsn.
 
there is also a platinum coating on the filament ..platinum is a catalyst and reacts with alcohol ....so , compression + platinum+ fuel = glowing plug ..and boom ...

some plugs will look good and glow when you hook up the glow warmer , but the engine will stall as soon as you unplug it ....thats because the platinum coating is gone ..so no chemical reaction with the fuel ...and wont run
 
So will the platinum burn off the glow plug wire if the engine is too lean, or does it just burn off with time.

Thanks
Newfienew
 
I would also check for a possible crack in the block and seal the engine if it's ok. It could be a hairline crack that's not causing much trouble until you try to run it hard.
 
Thanks to all who helped with the problem. I ran it tonight with a new glow plug in 8 degrees celcius, and man it screamed. It was perfect. I did have to slightly retune as it was a little lean. I reset everything to factory settings and went from there. By the time I had half a tank gone it was wheelie on demand and mad speed!!!!! All seems to be well and I've learned a lot about how glow plugs and the glow system works this week. I was always under the assumption that glow plugs were for starting the engine only. I had no idea they stayed glowing once the engine was going. Live and learn I guess.

Thanks again to all who responded

Newfienew
 

RC Builds

Back
Top