I'm running a manual Opel Corsa 2005 Sedan (engine code: C16SE, 1600cc). The problem I'm encountering is that the car won't reach its maximum speed of 200km/h as similar cars do. Instead, it stops accelerating at 150km/h no matter what I do even with the gas pedal floored. I have replaced my worn clutch and the new one works great (apart from this problem) so I exclude that. Here are some info and notices that might help:
- The engine turns on normally and idles just fine
- Accelerating from zero up to 130km/h is smooth. It is harder to go past that but eventually the car reaches 150km/h (i.e. takes more time to gather speed)
- During idle, 1st, 2nd, 3rd, and (maybe) 4th gears, the engine RPM can reach 6400 and cut-off as designed. On 5th gear, however, RPM can't exceed 4500. So RPM stops at 4500 plus car speed stops at 150km/h.
- Gas mileage is fine for that car
- I'm using the recommended fuel as per the owner's manual
- Using 10W-40 semi-synthetic oil, suitable for the engine
- Air-filer was replaced 12 months ago and used for 9,000 km and was cleaned once since then
- Fuel-filter was replaced 14 months ago and used for 10,000 km. The mechanic have cleaned it once few months ago and it was OK.
- I sense some misfire even at idling like pulses that I feel them under my feet
- Sometimes check engine light comes on at speeds between 130-150km/h then turns off when I slow down to below 130km/h
- Timing belt was replaced 6 months ago and no sign of improper installation
- Spark plugs last changed since 10,000 km (14 months ago). I also replaced the wires 7 months ago.
What could be the reason for the lack of acceleration bearing in mind the car's behaviour as explained above?