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Mark, Auto Service Technician
Category: Ford
Satisfied Customers: 1504
Experience:  Qualified City & Guilds
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Hi, I have a 2004 ST220 Mondeo (3.0V6) which suddenly developed

Customer Question

Hi, I have a 2004 ST220 Mondeo (3.0V6) which suddenly developed an intermitant misfire on idle last week, the misfire became progressively worse and on the way to a friend who is a mechanic the vehicle suddenly suffered total power failure, the vehicle started again but was popping back into airbox and stalled, no further attempt was made to start again and a visual inspection was carried out under the engine cover for anything obvious but all appeared ok.
I called the AA who attended and the patrol could not access the ecu via his scanner and the vehicle would not crank, it was then found that the engine management 7.5A fuse had blown and kept blowing when cranking or ignition energised, the patrol eventually replaced this fuse with a 15A fuse? to my concern but informed me this would be ok?, he carried out further checks to establish power at coilpack, starter, fuel at rail etc all ok but was still unable to access/connect with the vehicle with his scanner. The patrol then recovered the vehicle to my house and reckoned it was the alternator. The following day my friend collected the vehicle and began trying to solve this problem, with the help of an auto-electrician they established that the resettable fuse they had temporarily fitted did not trip when the coilpack was disconnected, so I purchased a genuine coilpack and eagerly fitted it but still no start? I then checked for spark with a sparkplug in the end of the accessible ht leads and no spark present, I was beginning to suspect my fears that the ecu was damaged when the coilpack failed as during checking for voltage etc at coilpack we could not detect the triggers from the ecu. The following day I made enquiries with an ecu repairer who informed me I would be wasting money on crank and cam shaft position sensors and suspected the ecu was damaged and wanted the number from the ecu, I removed the ecu from vehicle and due to the nasty smell I opened it up and could see that several trisistors were burnt out/damaged, i gave The ECU Doctor the numbers as requested who informed me he had a schematic for my ecu, the ecu was promptly sent for repairs. I received the ecu back after repairs and fitted it to my vehicle where it started immediately but still had a misfire, we scanned the vehicle once warm where misfire was still present and no faults or codes were detected but could see the previous codes etc prior to reset/clear, I drove the vehicle home and its got no power, I have put x6 new genuine plugs in tonight and a UIM breather that was split to eliminate and have pulled off leads one by one but it still sounds like its running on 5 cylinders, I have even put back on the old ht leads but no change.
will be calling the ECU Doctor in the morning but would really appreciate any advice with this problem, thanks in advance
Submitted: 4 years ago.
Category: Ford
Expert:  Mark replied 4 years ago.

markthebooler :

Hello. My name is XXXXX XXXXX I will be assisting you today.

markthebooler :

Where you able to determine what cylinder was misfiring when you pulled the leads?