PwnMe

Just need a little bit of help for my Tmaxx.

It's a 2.5 Tmaxx project truck with the 3.3 and the slipper clutch upgrade. I bought it used. The truck is an absolute beast when I hit the throttle, zero hesitation. The engine dies after 4 seconds of pinching the fuel line so everythings fine with the LSN.

The issue is that the truck past 3/4 will bog down. It will then clear out and run. Also if I mash the throttle the exact same thing happens, but if I don't let off it'll stall. It never reaches the point to shift. I thought about lowering the point for it to shift just to check to see if it even will since I bought it used.

I read many many posts on this situation. Some people claim that it's too lean and isn't getting enough fuel at those RPMs. Some people claim it's too rich and is flooding the engine. Another major issue is that at about a half tank it'll stall. Also it's horrible to start, but I blame the crappy EzStart.

So two questions

1. Is the engine too rich or too lean? I've reset to factory and attempted to go in both directions with the needle with really no major change.

2. Is the crappy tune of the engine preventing the shift? If I run at 3/4 of the throttle and it doesn't bog down it still never reaches the shift. It'll run in first gear all over my yard.

Also the engine is newer and I bought it. It was broken in correctly.
I was gonna post a few fun pictures of it in action, but guess I gotta wait til I acquire some more posts.

bobbyc1127

iTrader: (7)

I would say check for air leaks in your fuel line and tank as well. BUT also...it does sound like you do have a tune issue...now is it to lean ot rich I would have to listen to it...but check the fuel lines as well as the pressure line and make sure everything is tight and no leaks...also is the sleezy start new? after the shaft wears on the brass bushing on the back plate that will also allow for a air leak also...

PwnMe

Any simple way to check for airline leaks? Tank is sealed pretty tight I'm sure. I'm gonna pull the engine and the tranny off later and look the inside of the tranny over. Also it idles pretty crappy. It'll heat up and if I hit the throttle I get an automatic stall. I tried leaning it out with no results. Damn near impossible to start after that.

bobbyc1127

iTrader: (7)

how old is the motor? how much fuel have you ran through it?

ckblood05

iTrader: (15)

when you give it full throttle is there alot of smoke coming out the pipe?

got_nitro

iTrader: (24)

Sounds like your tune is messed up from the "Also it's horrible to start, but I blame the crappy EzStart.." No air leak no anything else. The 4 second "rule" on your pinch test is just a quick way to make sure you are with in the range. If it's dieing out at 3/4 throttle, it's starving for fuel.

Your LSN is too rich and your HSN is too lean. Most common tuning problem.

PwnMe

Too cold and dark for me to attempt tuning anymore tonight.

Here's a small update and some details...
I tore apart the entire transmission, everything is in perfect working order. The screw for shifting was tightened almost the whole way and the other screw was way too loose that holds the gear on. I suspect that's from the last owner so I fixed that issue and loosened the shifting set screw 2 and a half turns.

The engine has only had about 6 tanks after break in. I did it myself during a warmer time of the year and it went in storage for a little since I had an insanely busy summer. I am eliminating the engine as an issue.

The smoke is a bit of an issue, I have the exhaust aimed out the bottom of the truck. It appears as though some smoke is coming out and when it is at an idle is makes the wet grass under it smoke. I wouldn't say noticeable smoke, but I know it's not damagingly lean.

Got nitro sounds like he may have the answer. I am gonna completely start from factory settings tomorrow and see if I can get it to richen.

Another fact that may point to it being too lean... It will stall after about 5 minutes or a half tank of running. I'm assuming this could be due to it being too lean. How many turns of the HSN should I go in the rich direction before I rule out the mixture being wrong?

Also a random little side note... I respect the fact that I may have originally posted in the wrong forum, but the Nitro Offroad forum clearly states "For discussions of nitro-powered off-road vehicles, from buggies to monster trucks and everything in between." Perhaps that should be changed.

got_nitro

iTrader: (24)

Lean out your LSN (the engine will start to rev up high RPM's) now, turn your idle down.

Lean out your LSN till you can have a nice, easy low idle, your idle gap should only be about .5-.6mm. That's a .5 to .6mm idle gap. You will know if you leaned it out too much because now you will have a lean bog (out of the hole) with little to no smoke. If thats the case you simply turn the LSN back out 1 hour on a clock. Doing this it will make the idle even LOWER now. To fix this you simply turn your idle back up.

Once you get your idle down and a nice out of the hole launch (only holding it open for about 4 seconds), now it's time to tune the HSN.

If you can hold it wide open and it revs up now and shifts right (which I doubt because it's lean up top) with a nice smoke trail then leave it alone. If you have a nice launch and it revs up and starts to lean bog with high RPM's like you have now, you want to richen up the top (HSN) 1 hour at a time until that goes away. Now it's tuned...

PwnMe

You sir have taught an idiot how to tune in one post. Trucks starting on the first try, with zero hesitation and still smoking on launch, and no bogging down at high RPMS.

Still no shifting, but since I took apart the two speed that's probably on my end.

Thanks a lot dude.

got_nitro

iTrader: (24)

No problem.

ClintonRC

if a guy were to tune from the LSN first, something thats affected directly by the HSN, according to the manual.

ive been taught that tuning the HSN first, because its what controls the pressure to the LSN, then following up with the LSN and finally idle.



if you turned on the tap a little to your house, then flushed the toilet you will see less water flowing out of the tap because the system before it has less pressure, then when the toilet tank fills up and stops using water, the pressure becomes up to normal again. making the water out of the tap flow faster, even though its not fully open, like before.

just axing.

got_nitro

iTrader: (24)

Your right, in most cases this is the correct way. Going off of what the OP has typed I knew exactly what his problem was. I would not normally tell someone to tune the LSN first but in this case I knew his HSN was almost there. (lean bogging at 3/4 throttle) and LSN (bogging out of the hole)

Had it been a different problem he was describing, I would have typed a different way to tune (accordingly)....

ClintonRC

fairs enough. i only know enuff to keep my truck rippin fast enuff