Problem solvin' - TDCi

[Frikkin Evil]

OK, so I reckon there's a few knowledgeable types on here who like a challenge.

I bought a Mondeo TDCi to replace my Focus, which was... tired.

All was well and good until Wednesday, when an intermittent fault raised it's ugly head.

After driving for 20 mins or so, when I pull up to a junction or lights, the car appears to go into a limp-mode like state when I pull away. By this I mean that the revs rise really slowly, even with full throttle. The car is still drivable, but acceleration is... not very.

This state continues until the ignition is turned off, and upon restarting everything is fine... for a bit.

This loss of power has only so far occurred after stopping the car at a junction or similar, and not whilst driving in gear.

No error codes have been registered in the PCM, as far as I am told by the mechanic who looked at it, who is also baffled.

Does anyone have any ideas? I have a hunch about the clutch position sensor, but I havent been able to check yet.

[Chris_de_Bear]

Can't speak for mundaneos but my last 2 frog hdi cars cut power when braking so would be worth checking brake lights go off.

[simonst205]

Of all the sensors airflow sensors seem to be favourites for failing but would it always show an error code?
You would be best asking on a Ford forum or Googling. Good luck!

[Frikkin Evil]

Cheers. I have googled, but there's so much waffle out there! I will be going on a Ford forum too, but I know theres some clever clogs on here.

[silverspeed]

what diagnostic software was the mechanic using..?  I know numberous garages who use cheap data scanners to find pcm problems only to find their cheap scanners not reading properly..  ford suffer from numberous problems.. from air in the fuel system to the simple mass airflow..  All will show a fault code if going into limp mode.

We Has a simular problem at work with a vw golf .. turned out to be a poor flowing cat

[Frikkin Evil]

I'm not sure... I think he said something about a state-of-the-art SnapOn setup.

If what he says is true, and there's no error codes, then I have to presume I'm looking at sensor giving a false positive. The clutch or brake position sensors would fit this theory, and both tell the PCM to reduce engine power.

Gimme a 16 year old toyota any day!

[simonst205]

Anyone ever read about diesel particulate filters (DPF) fitted to modern diesel cars?
It has put me off ever buying a car with one fitted.

If it is the brake or clutch sensor why does it only go into limp mode when at a junction as you are constantly using these pedals when driving?

[Driveby]

DPF's are the bane of my life 

[Frikkin Evil]

Further developments... I have been on some long drives lately, and the car has dropped power twice. Both times the temp gauge suddenly sank to zero... like it wasnt reading at all.  Big clue? On hols at the mo, but will be getting stuck in at the weekend.

[Chris_de_Bear]

Check earths very thoroughly, especially engine to battery- and body.

[Frikkin Evil]

I meant to report back on this... a few weeks back I had a thorough look around the wiring on the topside of the engine, and had a 'waggle' of some connections etc. Nothing obvious was wrong... thing is, the problem hasn't occurred since! Must've been one of the connectors I waggled. Nice 1!

Thanks for all your input.

[Chris_de_Bear]

My pug's doing the very same thing at the moment, except the engine light is coming on. Normally does it on over-run, either stopping at a junction or just changing gear, normally when giving it a bit of welly before lifting off.
About to get an obd2 fault reader so I can trace it.

[Frikkin Evil]

At least if you're getting the engine management light, you should at least get a code to tell you where to look!