3.3 Tuning Problem

[joshman1204]

I have been having a strange problem with my 3.3 lately and I can't figure it out. The engine will not start and run on the same tune. What I mean is that I have to lean it way out to start it and then once it is fired up I have to richen it up almost 3 full turns to get it running properly.

I have never had this problem in the past but have been having it for the last few weeks and can't get it solved. The truck runs great but just will not start on the same tune it runs on.

I am running byrons speedblend 30% with a mccoys mc8 plug.

 

[Punisher]

So when you are running, what are you settings - how many turns out on the HS needle?

Should be 3-4 turns out depending on fuel, weather, filter and pipe . . . if you are running at 6+ turns I reckon you may have an air leak.

Seal the carb and back plate . . . .

 

[2revo1maxx]

Should be about 3-5 turns. Possibly more than 5 if it's cold out.
The high speed needle should not have any effect on starting, but if it does I'd have to say your lsn is too lean and/or you may have the idle set too high.

 

[Grave]

If running in cooler Air Temps try a hotter running glow plug

 

[ozziii]

3 turns on the needle of a 3.3 is a fair bit, them needles normally only need very small adjustments to make a difference to the tune, would have to be an air leak or something somewhere. Not sure what temp the McCoy #8 is but the 3232x (heavy duty) from traxxas is a hot plug so would be the one to use for cooler weather, well its the one Traxxas say to use all the time. The Mcoy #59 is hot & the O.S LC3 long reach is hot, both of which should be right for the 3.3, they are the same length as the Traxxas plug.

 

[2revo1maxx]

The plug heat range has nothing to do with engine temps.
I would run a medium or medium/hot if it's real cold out. If you were running high nitro, fewer shims, or an expensive aftermarket engine you would want to use a medium or even a cold plug in cooler weather.

The only way to make a nitro run properly in cold weather is to cover the head so it can run rich enough for the cold weather and still warm up to safe operating temps.

 

[joshman1204]

I think it is probably just a fuel/glowplug problem but I dont know enough about how weather and nitro content affect glowplug choice. I know that in the summer time I run 30% with a medium plug and it works great but now I am having hell with that combo. Strange thing is that I am still using the same fuel/glowplug in my XL and it is still working great no matter the weather.

I guess I will grab a hot plug and see if that changes anything.

 

[2revo1maxx]

It won't. Your problem is on the low end and/or idle.

I forgot, are you pre-heating the engine? That might be all it takes to get it going.

 

[joshman1204]

Put in a good hot plug and problem solved. I guess the little 3.3 just needs a little more heat than my big blocks.

 

[2revo1maxx]

A hot plug isn't going to provide any more heat, it advances the timing.