Hi all,

Here goes:

Problem started a couple of months ago with the Speedo dropping to 0 while driving. At the same time acceleration was sluggish. It would only happen for a short while and then return to normal. While the Speedo cut out if the engine was not revved it would cut out as the idle dropped.

Ford replaced the Vehicle Speed Sensor (VSS) on the gearbox as I was told this was quite a common problem. This did not fix the issue.

Another garage then looked at it and another diagnostic showed these codes:

PO340 - Cam Sensor Circuit Malfunction
P1131 - HO2 Sensor Indicates Lean
P1709 - Park/Neutral Switch Out of Self Test Range
P3382 - Undefined

They checked the voltage to a few components and recommended replacing the Mass Air Flow Sensor and a breather hose that was compressing. Again this did not fix the problem.

A third garage looked at it and said it was the Cam Shaft Position Sensor even though this had tested okay previously. It was replaced and a new Earth wire was run but did not help.

The problem became worse and the Speedo would cut out for long periods of time and the engine would cut out more.

I then called the AA and they said it must be a faulty Cam Shaft Sensor so I replaced it again. This did nothing at all and the problem was worse.

A fourth garage replaced the Coil Pack and took off the exhaust to make sure it wasn't backing up. Again this did not fix the issue.

I called the AA again when the vehicle kept playing up. This time it would start okay but idled really badly and as soon as the engine was revved it would cut out. This would happen repeatedly. If I disconnect the Mass Air Flow Sensor connector and rev the engine till warm then reconnect it then it runs okay but the Speedo still does not work.

The AA looked at the wiring connectors and recommended I get the wiring between the MAFS, VSS and Camshaft sensor to the PCM checked. This has been done by an auto electrician and he said the fault was with the ECU and he recommended taking it to Ford.

Parts fitted so far:

Vehicle Speed Sensor
Mass Air Flow Sensor
Cam Shaft Position Sensor (twice)
Coil Pack
Breather Hose
Spark Plugs and HT leads

Anyone got any ideas? Replacing & reprogramming the ECU is gonna be expensive so I would appreciate any ideas

 

P1709 sounds interesting. The car doesnt know when its in neutral or park so would probably have something to do with it wanting to stall.

You can try getting the ECU reflashed which will just update its software. This is something you could hazard a go at but judging by the extent of the problems, it probably wont solve them.

Disconnect the battery for about an hour then reconnect. This will erase the ECU keep alive memory and go back to a default set of settings.

 

The P1709 error was due to the vehicle being a manual not automatic and did not return after the error codes were reset. At least that's what I was told.

I have not tried disconnecting the battery will try that tomorrow at work. Beats doing real work I guess

The problem is strange. The weather was warmer today and the car started to work okay. The Speedo and tachometer came back to life and everything was good for a while.

The only other thing I forgot was that when the Speedo cut out if I went over about 40mph the digital tachometer turned to a series of lines like this ----- ----- and the traction control light comes on and stays on.

Thanks for your reply

 

What you have just said above especially the ------- indicates VSS. You've changed it though so a bit baffling why it hasn't fixed the issue. It's all to do with the VSS or at worst the PCM which means that the ECU is probably fucked but a reflash may cure this. Might have an automatic car's brain rather than a manual one for some weird reason so a reflash may solve this.