Hi
First try this.
Adjust your color wheel index in service mode. Increase or decrease number and see if it helps.
Press (Power→Left→Left→Up) to get into service mode.
If changing cw index won't help, then disassemble projector and clean color wheel photo sensor.
Manual here. http://easp.optomausa.com/ASP/upload/Service manuals/Optoma HD80_HD80-LV_HD803-LV Series V6.0(DDP3021, 36.87Z05G001) Service Manual.pdf