Problem with 1.6 2003 Focus, with Warning Light!

[AL...Ease]

Hey up, my brother's 2003 Focus has been playing up for about 6 months, it all started when he let it run out of oil (not very mechanically minded), which resulted in some misfiring and the management light coming on.

Since then he's had it to a garage who have replaced the O2 sender, leads, plugs and flushed the engine, but it still isn't quite running properly at low revs. He hasn't noticed a performance difference above about 2,000RPM, but when it's warm the idle is erratic, going from 800 to 600 rpm and sounds a bit rough.

The exhaust pops on the overrun sometimes and, with the airbox off, I noticed a lot of quiet popping coming through the inlet, which I've not heard on a car before. I'm no expert, but I fear that it could be something as simple as needing a pro (Ford) ECU reset, or could be as serious as valve overlapping.

Can anybody lead me to what could be the problem? If it sounds like something the main dealer may be able to sort we'll be happy, but they're known for over-charging, hence the reason he hasn't taken it there yet, so fingers crossed it won't be too expensive.

Cheers for reading,


AL

[Zad]

Early Zetecs were very fussy about oil, I imagine new ones will still have problems if they run out. The symptom is "tappet jacking", that is to say the tappets depress and open a valve, then get stuck open. That *can* lead to valve burn and can of course lead to it ejecting high pressure burning mixture into the exhaust and possibly inlet. The valve usually closes, but it will happen again. Presumably the solution is to get the hydraulic followers out and clean the appropriate oil spaces in the head and replace them with new "buckets".

Surprised the garage didn't think about that one.

[AL...Ease]

OK, so it's a head-off job, thanks for the info. The garage that he took it to wasn't a Ford specialist, just a friend-of-a-friend sort of garage.

[Dave_ST220]

Pretty sure the sticky valve problem was sorted yonks ago-Zetec first came out in Mondeo circa 1993 IIRC!!

[Zad]

Not necessarily head-off, I think the hydraulic recesses etc can be cleaned and buckets renewed with the head on. I know the original hydraulic jacking problem was sorted, my supposition was that if he let oil run low there would be a lot of debris, carbon and so on in the oil system and that as this was a previous weakness it may show up again under extreme conditions. It is something to put to the garage anyway.