General LSX Automobile Discussion - Fluctuating RPM in Motion

Well guys, figured I'd get your opinion. :D

Problem: While driving, around 2k rpm, the motor will literally surge a few hundred rotations back and forth, basically before the shift point, then it will shift like normal. I'm guessing that the transmission might be low on fluid, but I can't tell; the dipstick is good and covered in a film of fluid, almost like it's splashing up the tube, so I'm beating myself up trying to figure this out.

Mods: Performabuilt 2 4L60, 3300-stall, my own trans tune (never had problems with it before the Performabuilt), and of course motor work, tune, etc.

Let me know what you guys think.

Does it do it before lockup? It sounds like it could be torque converter shudder. My Grand Prix does this a bit.

I thought that it did, but I played with it this morning and it does it when it's locked up as well, so I now doubt that it has anything to do with a transmission. Still can't imagine what it could be.

BTW: It does it only at part throttle, so it maybe it's a slight misfire?

Check for a pending p1870 code. Sounds like the torque convertor clutch (tcc) going out. When it gets worse you will eventually have hard 1-2 shifts. There is prolly some stuff on it in the tranny section as it is a pretty common 4L60e problem....

Is it actaully doing it or just reading it?

It could be a cross over issue...

Check for a pending p1870 code. Sounds like the torque convertor clutch (tcc) going out. When it gets worse you will eventually have hard 1-2 shifts. There is prolly some stuff on it in the tranny section as it is a pretty common 4L60e problem....

Even with a brand new TC and trans? It started doing it the day I put the trans in. The 1-2 has always been a bit on the rougher side, but barely, and I've yet to pull the "Component Slipping" code. HPTuners isn't picking anything up.

Don't know what to tell you. From your description it does sound like a failing TCC but if it was resleeved when rebult and no code not sure...

Alright guys, I got an update: it's definitely a misfire at exactly 2500 rpm; no trans. problems. Sounds much simpler now, yet I still can't trace it. No plugs fouled, O2s are switching properly, MAF reads well, all metering sensors are seemingly good. Think it might be the tune? All input is welcomed!