Our W reg 2.0 mondeo estate has developed a stalling problem after the battery went flat ?
The car was left in an airport car park last week with the courtesy light left on, the battery was completely flattened ! After a jump start we got home OK (thanks Luton NCP) but now the car stalls when stopping (as soon as clutch is depressed). The battery has been fully recharged (reads 13.5 V with engine off) and car starts easily each time it stalls even with the lights on so I'm sure the battery is OK. Problem occurs hot or cold. When stationary the car will idle OK, only seems to stall when engine speed drops when pulling up ?
Right firstly the ECU will have lost its learnt idle adaption figure, which is basically the amount it needs to open the idle control valve under different circumstance to maintain the idle within parameters. (and vary igntion timing actually)
The fact that the ECU is taking along time to re-learn and its still stalling points to it needing a large adaption value which in turn meants the throttle body and/or ISCV is dirty and it cannot pass the air it should do, so the ISCV is needing to be opened further than necessary.
As you dont mention that the idle is poor or hunting when it is ticking over, we can pretty much rule out induction leaks or problems with the EGR etc etc.
If you feel competant you can remove the intake hose and scrub clean the throttle bore with some light solvent (brake cleaner or meths) of oily crud etc. You will need to hold the throttle open and clean this area as this is where most of the build up will be.
Ford kindly teflon coated the throttle body of black top Zetec's but IMHO this doesnt stop the build up, just delays it. Don't use carb cleaner-its too powerful and you will remove the teflon coating.
Be sure to check for split PCV and other hoses, and ensure you properly refit the intake hose, as any leak downstream of the airflow sensor will upset matters.
Lastly disconnect the battery for 5mins, then allow the ECU to properly relearn . They will usually do so unaided over afew days, but the proper procedure is:
o start engine from cold using no throttle. This may require abit more cranking than usual. o Without touching the throttle still, allow to idle for 5mins or so. o Drive the car normally at varying speeds for about 5 miles, but it must reach full operating temp. o Allow the engine to idle on its own for at least 2 cooling fan cyles.
You may notice the ECU is struggling to keep the engine at idle or that it varies about abit before settling, but should learn fairly quickly. If not, then you have a definate air leak or other problem.
Tim's post in this thread is spot on. The Ford ECU just needs to learn how to idle again, and how not to stall when you're slowing down. The only other thing I might try is checking that the electrical connection to the idle control valve is clean.
I almost said that maybe the engine had lost some settings, but then discarded the thought on the grounds that no serious manufacturer would be keeping the settings in non-battery-backed-up volatile memory. Clearly I was wrong, jeez, how rubbish a bit of design is that?
thanks all for replies, seems to have sorted itself out in the end.
The problem persisted for two days driving to work, 35 miles round trip cross country. On Wednesday I had to drive into the town which I wasn't looking forward to in the stop/start rush hour traffic but by the time I got there it had sorted itself ! I guess the first 100+ miles I did just didn't exercise the engine under the full range of conditions.
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