My 2000 1.8 has started having a problem with hitting an invisible rev limiter! It is a standard 1.8, W Reg with 75K miles on it and generally has mild use by my wife since we got it 5 years ago. It is running on E5 fuel.
Recently I noticed that if you tried to rev it hard it bangs and pops at 4K when hot and will not rev past that limit. So I tried it from cold and it will rev to 6K before the problem starts, but the warmer it gets the lower the rev limit. I’ve tried it in 1st to 4th gear and it is exactly the same in all gears when hot.
Below the 4K point it runs perfectly.
I did a plug chop and they seem fine but as a precaution I replaced the plugs and leads as it was the cheapest first option.
Clearly it seems that it will be ignition or fuel based but I wondered if anyone had any thoughts about what to look for next - I am only an average home mechanic so if diagnostic tools are required I will have to find someone to do that. But any thoughts about what I can look for myself would be appreciated.
Thanks very much.