Celica Poor Starting Fuel Consumption

Sounds familiar! I had similar symptoms on my old Renault Megane: rough engine idle, poor starting... It turned out to be the throttle position sensor. Have you checked the throttle position values with a diagnostic tool?

Thank you for your input. I haven't checked the throttle position values specifically. Could a faulty sensor really explain both the increased fuel consumption and the starting difficulties?

Yes, absolutely. On my Megane, the faulty sensor was sending incorrect data to the ECU, messing with the fuel/air mixture. This resulted in higher fuel consumption and a hard start. It's best to have it checked out professionally; probably a quick fix. I hope they can solve the issue in the workshop.

Understood. Thank you for sharing your experience. I took the car to the workshop, and the accelerator pedal module was indeed defective, causing the throttle valve issue. Repair cost was 205€. The symptoms are now resolved.