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98 1.3 engine management fusing (F28) - m-man
Ford Fiesta Finesse 1998, 1.3 efi endura-e
I was travelling along the M8 at around 2am the other morning, in my mk4 1998 Ford Fiesta (1.3 endura-e), the car had shown no signs whatsoever that there was a problem, as I had travelled 90miles prior to this in one go. As the motorway came to a junction where it splits(M9 SPUR) and I had to brake firmly down to around 40mph and went down into fourth gear, when I applied the accelerator to go round the vebd the engine stalled and the car rolled to a halt on the hard shoulder, I was quite stumped as there was no warning. I located the fuse on the side of the road and changed it for a replacement 15A fuse (this was fuse number 28 in the auxiluary fuse box under the bonnet) the fuse supplies the engine mannagement system. The car started with no problems and I decided to get going whilst the car was running, I travelled annother 2.5 miles and once I was about one third of the way across the Forth Road Bridge Northbound when the same problem occured, the rev counter dropped to 0 and the engine stalled again, this being one of the least convenient places in the entire country to break down, since there is no hard shoulder. The police showed up after a minute of 2 and by this time I had the bonnet up and was replacing the fuse again, since it had fused again. The car only travelled about ten yards this time and stalled almost immediately. Once the towtruck dropped me and the car off at the layby after the bridge, I toiled and toiled serching all the visible wiring and unplugging the ascosiated sensors (camshaft pos. sensor, throttle pos. sensor, mass air flow sensor, EGR solenoid, the fuel pump and both the 'power on' and 'fuel pump' relays, having not had any luck with any of these, and also the fuel injectors were working correctly also. I had deduced that it had to be an short circuit somewhere shorting against the body of the car somewhere, but this could be anywhere on the car at all. after I got towed home to burntisland, I had almost used up all my spare fuses, and all that I had left was a 30A fuse, double the correct rating, so I plugged it in and switched the ignition on, testing the m.a.f sensor and I noticed a small wisp of smoke and the unmistakable smell of burning pvc, coming from just under the air intake and m.a.f sensor. I switched the ignition off quickly and removed the passenger side headlamp unit and grille from the car. I then unplugged the sensor above the air filter(2pin plug) and the larger plug that supplies the mass air flow sensor, on this grouping of wires, which is taped up with black heatshrink tape, was resting at one point against one off the chassis rails where it comes out to secure the bumper to, but it was very sharp at the top of the chassis rail where the cable was resting under the air intake unit, obviously this sharp weld has been chaffing at the wires forr the last 11 and a half years and just wore through completely the other day. I had to chop and crimp a new set of wiring from the point where the short had occured the heat had caused the cables to fuse together partially.
The reason I felt the need to post this thread was that it took me two days nearly working with a meter and haynes wiring schematics and it was one little short on one wire that caused me all that bother. It also occured to me that this must be a common fault on mk4 fiestas(and possibly the mk5's aswell) since the donor car that I took the replacement wiring from was starting to chaff also and given time would have ended up with the same problem as myself. there also did not seem to be one other person that had had the exact same problem as me when I was searching for a thread that may have related to me yesterday, it really is a big problem when your engine management system develops a fault because the circuit in question(28)aux.fusebox supplies many things, and all of which are essential to the engine's running.

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