Trying to solve a weird hesitation and bouncing revs issue on a 2002 Ford Focus with a 1.6 16V 74kW Zetec SE engine, I encountered a fair amount of people suffering the same symptoms for thousands of miles. You can see these issues mentioned quite a lot on the internet, but almost never is the solution mentioned. If the usual spark plug, HT leads, coil pack or throttle position sensor do not solve the issue (and quite often they don’t), it might seem there’s nothing really wrong with the engine, yet the intermittent hesitation remains. Even pretty experienced mechanics seem to be left scratching their head.
I’ve spent a month trying to solve this. I was pulling my hair and going crazy. Until I came upon a video with the very same issue that ultimately lead me to a discussion on engine timing. Some people were claiming that they’ve solved problems like this by correcting the engine timing (it’s pretty easy to mess up engine timing on these Zetecs).
Took me another two weeks to find a shop to find the issue and correct it. The first shop I went to had the car on diagnostics for two days, but in the end, they said there’s nothing wrong with my engine’s timing and that the engine runs and sounds fine, just that it’s simply old and doesn’t have all that “bite” anymore.
Unconvinced, I went to a second shop (to an authorised dealer this time) and straight out asked for a very thorough engine timing check. I was once again told that it doesn’t make any sense, that my car runs more or less fine (which it supposedly wouldn’t if the timing was wrong) and that checking timing is a waste of time. Nevertheless, I was able to convince them to do the check anyway.
And what do you know? The engine timing was off one tooth on both cams. And it might’ve been like that for thousands of miles – ever since the timing belt was replaced by the previous owner in a pretty reputable Ford dealrship – it wasn’t any garage mechanic doing the job. Unless someone went in after that and messed it up – i have no way of finding out, of course.
I’m not saying that if you suffer from similar issues, your engine timing must be wrong. No, there’s loads of faults that can be causing similar symptoms. But if you do suffer from such issues and nothing seems to solve it – do yourself a favour and get your engine timing checked thoroughly. You might be in for a surprise, just like I was.