Modern question. Any modern mechanics?

[danthecapriman]

A little while ago I posted a help me thread about a 2008 Ford Focus 1.8 duratec (petrol).

The car was running like a pig, almost like a mis fire when driving which was at it's worst at high speeds. In the end the seller of the car took it back, swapped the EGR valve for a new one and gave my dad the car back. It seemed ok for a while but for the last month or so it's been mis behaving again. Same problems as before but not quite as bad.

I couldn't find anything obvious so advised my dad to get it looked at by a local Ford specialist.

The car has come back now and is fixed, it drives absolutely beautifully now.

 

The fault was that some how the ECU had allowed the car to permanently run in a state where it was suffering pre ignition, all the time! This had caused horrific fuel economy, poor starting, the mis firing issue, and was also making a mess of the spark plugs. Obviously, if it wasn't sorted soon it could start doing some far more expensive damage.

So the mechanic has deleted all fault codes, re installed the latest ECU data and updates (it had never had any updates since new) and did a few other jobs around the car while he had it. As I said, whatever he did it's undoubtedly done the trick.

It didn't have any sensor faults or anything like that changed btw.

 

Now my question. Why and how could this possibly happen?

I was under the impression that an ECU was programmed to run a certain way under certain conditions and things like timing etc wasn't able to 'unset' itself like it could on an old distributor fitted car.

The only thing I can think of is someone having a go at an ECU reprogram and seriously screwing it up.

The mechanic said it was easily the worst he'd ever seen for this and was surprised it was still running!

I'm not really into moderns and draw the line at mechanical injection systems so I'd just be interested to know how this happened.

[Asimo]

A lot of cars seem to pink for a few seconds if something pushes the engine controller into limp mode.

Supposed to reset themselves after a few miles......

[hauserplenty]

The installed software often needs to be updated, either by the dealer or a technician with dealer-specific software and tools. This software is sold on a subscription basis, so is not cost-effective to own unless it is used. It is manufacturer-specific, and also needs updating, e.g. when recalls are issued.

 

A scan tool is read-only, but usually a laptop with a special OBD-II interface and the correct software installed is used to "re-flash" the memory, usually of the PCM but all the modules can be selected. Usually a battery charger is to be connected before starting this process, but often it is not. If the battery died on your Dad's Focus while this update was in process, or somehow the update did not install correctly, that could explain it.

 

See your dealer for details...

[danthecapriman]

A lot of cars seem to pink for a few seconds if something pushes the engine controller into limp mode.

Supposed to reset themselves after a few miles......

This things done about 1000 miles or so running like this with my dad, plus however long the seller had it running like this! I just hope it hasn't done any damage to it.

 

The installed software often needs to be updated, either by the dealer or a technician with dealer-specific software and tools. This software is sold on a subscription basis, so is not cost-effective to own unless it is used. It is manufacturer-specific, and also needs updating, e.g. when recalls are issued.

A scan tool is read-only, but usually a laptop with a special OBD-II interface and the correct software installed is used to "re-flash" the memory, usually of the PCM but all the modules can be selected. Usually a battery charger is to be connected before starting this process, but often it is not. If the battery died on your Dad's Focus while this update was in process, or somehow the update did not install correctly, that could explain it.

See your dealer for details...

Makes sense.

It's funny you mention the battery going flat. I had to change the battery not long after my dad got the car as it kept going dead after a couple of days. Alternator was ok but I wonder if it wasn't holding charge fully or went flat when it was last hooked up for an update? Seems possible after what you said.

The mechanic said he couldn't find anything to suggest it had ever been given an update but if it had but the update didn't install properly then that might explain why.

 

 

Thanks for the education on this gents, it's not something I'm very experienced with. I don't tend to get on too well with computer type stuff.