Engine Mechanical problem
2000 Ford Focus 4 cyl Automatic 87,000 miles
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Are you ready for a challenge?
My newly licensed son purchased a 2000 ford focus with 135,000 miles on it He loves the car but a week after he bought it the engine died. The used car dealer even though it was bought as is, put another used engine in it for us. This engine even though we really know nothing about it supposedly has like 86,000 miles on it. When he got the car back it started stalling intermittently. It would go a week with no problem and then 2 days of stalling then nothing again. We took it back to the garage and nothing shows up on the computer and he cannot duplicate the stalling. We take it home a week and half no problem then stalling starts again. Bring it back nothing shows up on computer so he changes the idle air control valve. We take the car home and the ignition switch locked up. Had that replaced and went a week and the stalling started again. There is no rhyme or reason. It stalls cold it stalls warm and it stalls so far only when idling in the drive position, when at a light or stop signs. I was told if I took the car to the dealer it would be hard to find the answer if it can’t be duplicated and the price would be great if it had to be looked at for a long time. This is an old car that when running, runs well. I have searched the internet and see that the ignition switch is a common problem with the 2000 as well as the stalling. I however never find a real solution. Tomorrow we are changing the fuel filter. I am hoping you have some other not to expensive advice to offer?

Thanks much for any help you can offer.

It could be many things: (I assume the ignition switch and the IAC valve you replaced are working properly)

*Could be a fuel related problem (lean mixture); check:
- vacuum leak
- MAP sensor
- Throttle position sensor
- dirty injector
- dirty plugs etc

Chek also:
- faulty PCM

Also Ford has a bulletin for Focus with stalling problem during cold weather: it's something about the PCV valve.

There's something else you can do if you're patient enough:
sooner or later this intermittent problem is likely to turn into a daily problem, which should make it easier to diagnose at the shop.

It could also be that all you need is a tune up.

Yes the stuff we replaced are working well. Today we will change the fuel filter. We had the vin # checked and this car was not involved in the fuel pump recall. I will take your advice and have all you mention checked as well. However wouldn't any of the things you mentioned show up on a computer? nothing does. Thanks for your help

There are DTCs for the parts i mentioned indeed, but many problems in a car don't set a code.
Also, have you checked for 'general' codes only, or have you also checked for manufacturer specific codes?

Also, I forgot to mention to check the EGR valve.

If you suspect a fuel system issue, i would do a fuel pressure test, check for leaks and/or low pressure.

Let me know how it goes, it's always hard to diagnose a problem over the internet