Expert Tuner Needed - Please Help.

[Blackbird85]

I need some help. I have run and tuned plenty of nitros but this one for my friend has me stumped. It a Traxxas 3.3. It has compression but not much pinch. I finally got it to idle but I have two scenarios that seem inconsistent.

When I squeeze out full throttle at any speed the engine bogs then revs then bogs then revs etc. Suggested to me that it was way rich but when I back off the HSN a little it hits high rev but won't slow down for a few seconds after I release the throttle. The same at idle. I give it a little throttle and it runs at a high RMP even when I let off the throttle.

Temps are OK, electronics are working perfectly. Any ideas?

Thanks, Bill

 

[Rolex]

Very possibly an air leak somewhere in the system. When all seems right, and you still can't get it tuned, that's the usual cause.

 

[olds97_lss]

Well, when you adjust the idle on an overly rich engine so that it can idle, your idle is set too high when the HSN/LSN are tuned correctly.

After leaning out the HSN a bit, did you happen to back the idle screw out a little to compensate? Or did you adjust it and not notice a change?