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That bloody Zetec-S 1.25l (June 1998 build)

OK - I've now changed the ICV, changed the TPS, reset the ECU several times and the problem is just as bad as ever. I drove from Oxford to London the M40 last night and was actually shouting at the car by the time I got to London. It's not funny rolling along at 5mph in a heavy jam with the engine doing 3000 revs! The car actually accelerates all on its own if you get it rolling in 1st or 2nd gear. Not much but it definitley does accelerate up to about 3000 revs, even with the clutch engaged. This can't be right! The choice between silly over-revving or using the clutch as a brake for the engine is not a good one!

A bit more experimentation shows that dropping the clutch briefly drops the revs, but then they climb again if the car is moving. I guess the ECU must know the clutch is being dipped and obligingly drops the revs with it. So I can coast along at reasonable revs by sitting in neutral and pumping the clutch about every two seconds. Clearly I don't generally coast much but you know what it's like on a heavily congested motorway...

I am convinced there are no air leaks and I've checked the throttle cable and am sure it is not sticking and that the throttle is closing properly. Nothing else is obviously wrong so I am now rather stumped.

Disconnecting the speed sensor that sits on the gear box (where the speedo cable attaches) completely solves the problem and the car seems to drive perfectly at any speed and with just as much poke as normal. I am tempted to leave it like this but I'd rather get the problem fixed. The VSS must be there for a reason! I'm a bit loathe to change the VSS until I'm sure that's the problem (although the fact that disconnecting it cures it would seem to point that way). What do people think?

Is there a firmware upgrade for the ECU available that might solve the problem?

Thanks in advance, and sorry to keep boring you all with this.

Tony

Reply to
Tony Brett
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In message , Tony Brett writes

[snip]

I think you are going to have to bite the bullet and change the VSS. You seem to have covered everything else.

Reply to
Paul Giverin

Thanks Paul,

Did anything else I said in the first post sound at all worrying or is that all expected behaviour?

Tony

Reply to
Tony Brett

By all means replace the VSS, but as far as I am concerned it is doing exactly what it should, but the ECU is raising revs too much.

I'd have the ECU checked for lastest firmware first.

Tim..

Reply to
Tim..

In message , Tim.. writes

The VSS is the cheaper option though. I'd have thought that if the problem was with the EEC firmware then there would be hundreds of Festers with the same problem and there would be a TSB for it.

Also ISTR (although I can't be sure) the OP said that the problem started suddenly which would point to a component failure.

Reply to
Paul Giverin

So how is it then that if I disconnect the VSS then the engine runs just fine and doesn't over-rev? It still holds the revs up a bit on when the clutch is disengaged but now only up to about 1200-1500 revs and only for a few seconds. This seems much more like things should be!

Surely there must be a record somewhere or which firmware was being used in June 1998 (build month code WU) and a record of whether there have been any updates released? Where can I find that?

Many thanks,

Tony

Reply to
Tony Brett

OK - the VSS is 60 quid plus vat so I went to nice friendly local garage who ran diagnostics and the only fault code is coming from the power steering switch (that tells the ECU to increase the idle speed if you are moving the streeting wheel while stationary). He doubts very much that the error is coming from the VSS (as it does not show errors) but doesn't think the power steering switch could be causing such a problem either.

Next suggestion?

Tony

Reply to
Tony Brett

Tony Brett wrote on Tue, 13 Dec 2005

07:29:22 -0000:

I had a very similar problem with a Fiesta with a 1.3 Endura-E engine (2000), turned out to be a problem with the inlet air flow/pressure sensor (I forget which engine has which, IIRC, the Endura-E has a Manifold Absolute Pressure sensor and the Zetec has a Mass Air Flow sensor). That showed up in the ECU fault codes though.

The symptoms I had was that pressing the clutch in a slow-moving queue caused it to over-rev, and it generally didn't do much engine braking...

Reply to
David Taylor

Ford have a TSB stating that erratic idle can be a fault of the ECU, & reprogramming the firmware is required to solve the problem (TSB 82/1997), but they say a revised ECU has been fitted since Aug 1997. Is June 1998 defiantly the build date (my escort was registered aug 1997, yet the build date is early 1995!)

Reply to
Dave Griffs

Yep, last two letters in VIN are WU which says to me that build date is June

1998. 1st registration is Sept 1998 so it sounds about right. See
formatting link
for build date info. Tony
Reply to
Tony Brett

I wouldn't rule out the power steering switch though. Although it doesn't affect the idle speed by much, the ECU has triggered a fault code & it could be running in some strange mode due to this.

Reply to
DR.CLAYTON

I've just had Ford run through the disgnostics and they are pretty sure the problem is comming from the PAS pressure switch and have prinouts to prove it. I've just left it with them to try and sort it out. I dread to think what this is going to cost but there seems to be no other option now :-(

Tony

Reply to
Tony Brett

OK - problem now solved. It was not actually the PAS switch but a connection to it that had gone open circuit. Ford did a small repair to the wiring loom and it is now fixed, or so they say! Total cost £171. Plus the cost of the futile ICV and TPS. I'm glad I didn't get a VSS too!

Anyone wanna buy an ICV or a TPS :-)

Tony

Reply to
Tony Brett

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