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Speedo & ECU - My Story
Jan 2013 - Bought: Ford Focus - 1.4L - Mk. 1 - 2001 - 110k miles.
Right from purchase the speedo would occasionally cut out.
When cut out this effected the ECU.
When speedo cut out car would stutter with its fuel injection because ECU is confused.
When speedo comes back to life, car is fine again until speedo cuts out next time.
Feb 2013 - This speedo starts to cut out every journey + the stuttering.
The fuel injection stuttering starts happening even when speedo hasn't cut out.
At the same time the engine begins over revving itself when car is stationary.
At the same time the engine struggles to accept fuel when putting foot down in gears 1, 2 & 3.
I research the issue, bought and fit a new speed sensor:
Speedo ceases to cut out, happy days.
However the fuel injection stuttering/over revving/ engine struggling to accept fuel remains.
Perhaps I left problem for too long: confused ECU has damaged something else? Very common Ford problem. Does anyone know of a solution to the problem?
Try disconnecting the battery for a while to get the ECU to relearn your driving style.
This may help sort your car out.
Make sure you have your radio code first though.

Much obliged Stoney ta.

Do you mean disconnect the battery then bump start it and drive for a while?


Disconnect and leave to stand for 20 - 30 minutes then reconnect and start up then take for a good drive.

Your an absolute star mate thank you, I'll go and do that now and get back to you :)


how did your fresh drive go?


The engine started and over maintained revs of between 1200-1300.

Gently drove it for a little while.

The drive was so responsive!

Better than it used to be!

I then started getting carried away and gave it a little rag (showing it gentle/harsh).

Engine got warm and then it started stuttering a little again.

It's ok though, a very nice drive actually.

Should be fine I'll just have to deal with it for now.

Thanks for your help Stoney ;)

Welcome, hopefully it will continue to balance itself out the more you drive.

The stuttering and over-revving remains.

I have ordered a Ford Focus Throttle Position Sensor (TPS).

I have booked it's MOT + new TPS installation for this Saturday so I'll let you know how she drives!

Fingers crossed it's that.


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I purchased a cheap throttle position sensor from ebay for £15 (genuine part normally costs £70), fitted it and didn't solve the problem, so moving on.
After some research this is what I have found with regards to the stuttering/fuel starvation/misfiring ::: :::
This common fault of misfire on two cylinders or complete non start is often caused by the ignition coil pack shorting out on the vehicle - it is very important that the ignition coil pack is replaced at the same time as refitting your ECU after it has been repaired - or your faulty coil pack may damage the repaired ECU. -
EXCELLENT thread from on this topic :::
Lots of detail into this very common Focus MK1 98-04 fault here: 
How I think the problem occurred :::
I believe that when the speed sensor started malfunctioning I continued to drive the car, which may have caused the faulty speed sensor to damage the Ignition Coil Pack which then damaged the ECU.
How I'm going to tackle it now :::
Take out the ECU, read it's part number and send the ECU off for repair/replacement by for (hopefully) £150.
Purchase new ignition coil pack for £25.
Will let you know how it goes :)

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