Check the placement of teh temp element on teh onboard gauge. I use one on one of my TMaxxes and had to move it a few times to get it to agree with my raytech ir gun's temp from shooting the glowplug.

The temp sensor can't be too close to the exhaust and needs to be in a fin height wise so its close to the same height as the shoulder of the glow plug. I had to move my sensor so it was as close in to the plug as possible - up against the innner wall of the cylinder head. Can you borrow a good IR temp gun to double check the onboard?

Ideally, the onboard temp should agree with what a good IR gun sees, or you may be making wrong clnclusions about temps you're reading. TRX engines tend to run hot, here at 90F ambient, mine run 270-280F with good smoke and good punch. That's about as good as it gets. If yours is running 270 and its 50F ambient - that is too hot.

After tweaking the location of sensor on mine, it agrees real well with my raytec. I don't use raytec for it anymore - I'm confident it reads right temp. Now if the batt would just last a little longer longer!!