Lost in France

[Welly]

Oh noes, computer-me-bob diagnostics by someone who don't do computers

Warning you are about to Format the ECU, are you sure?

[yes]

waits.........


*Rings Brother*

[steve_earwig]

Middle of nowhere, only contact expensive mobile phone... even knowing what I know I wouldn't like to try it

+++Divide By Cucumber Error. Please Reinstall Universe And Reboot +++

[Doggy]

Not much progress - he can't get PP2k to work, suspect I have a damaged / loose USB connector or cracked PCB.

Trying to think of an alternative way forward.

[Welly]

*ring ring*

AA: Hello AA recovery how can we help today?

Doggy: "errm, I've err, broken* down* on holiday* in France and need recovery to Northamptonshire"

AA: Ok Mr Dog let me check your policy.

Doggy: sh*t

AA: Everything is covered all ok for Europe sir so we can help you, can you explain where the car is and what happened?

Doggy: Well, you see, I was driving along when.............



??????

[Doggy]

Mazingly enough, he's made some progress. (Someone showed which orifice the USB lead was meant to be plugged into).
He got it connected to the car and read the fault codes last night before running out of laptop charge & daylight.
- The usual pre-post heating relay message and one indicating a faulty MAP sensor. (My guess is they've had this unplugged with the ignition on).
He'll have another go today and hopefully get some fuel pressure numbers, I'm betting that's his problem.
We shall see.....

[Doggy]

I tried to get it going today and failed.
It would start but not idle and stopped immediately if you touch the throttle.
Got the computer talking Ok, checked the TPS readings (fine), started it up - would only run for about 5 seconds each time, but enough to verify the fuel pressure and turbo readings were both sensible.
Swapped the fuel pressure regulator for a 2nd hand spare with new seals, it was definitely better, but still not right. Starts every time, settles on normal idle for a few seconds, then falters, slows and stops. It will respond to throttle, but only in the first few seconds after starting. It will keep running unevenly at 5-600 RPM and smokes a fair bit.
In the 5 seconds or so after starting it idles smoothly and sounds perfect, so I don't think there is anything mechanically amiss. Feels like it does the starting part perfectly, but can't do the running part for some reason.
Law of Sod then kicked in - my laptop or PP2K refused to work again, tried every trick in the book, but couldn't restore comms for any diagnostic info. Maybe a heat issue, over 35 degrees here today.
Occurred to me it might be the lift pump, except it's always perfect prior to starting and we think it keeps going until after the engine stops, so not likely. I'm now thinking intermittent cam or crank sensor, (even though no fault codes to confirm).
Really frustrating not to get the diagnostics going as I really think I could have seen what was wrong with it idling continuously, but unevenly.
Ran out of time, (back to UK 1st thing tomorrow), so that's it for now / maybe for good.

[steve_earwig]

Blocked pick up screen?

This is all above and beyond but it's starting to sound like a dead horse

[Doggy]

Good suggestion. (Wish I'd though of it earlier).
Doesn't completely fit the symptoms but worth eliminating. I (belatedly) realised in could be the fuel pressure sensor giving the wrong info - I think it's supposed to run in limp mode with it disconnected. There's probably time to get him to try those 2 bits before he travels back on Wednesday, I'll let him know.

[Doggy]

He couldn't find the rail pressure sensor, but got it to run better by undoing a vacuum pipe - from his description, one of the ones on the egr electrovalve.
(His egr is blanked off and both air doser valves have the vacuum disconnected. I think the swirl flap valve is disabled, but can't honestly remember).
That means the only remaining vacuum operated device is the turbo actuator, it's likely disconnecting that hose would increase the boost. Normally that doesn't help, causing overboost/EML/limp mode. Maybe in this case it's compensating for a boost leak or intake blockage?
With the hose off, he got it to tick over more or less properly, got it warmed up and found he could then rev it to 3000+, (still unevenly) and it was possible to move the car a bit under its own power, which was previously impossible.
He hasn't checked the strainer as access is really awkward where the car is and the ability to rev seems to indicate it's not suffering fuel starvation.
At times it will briefly run perfectly smoothly, so I think its mechanically sound.
If it's getting enough fuel, that leaves not enough air or incorrect injection timing to my way of thinking.
I'm wondering if it could be a loose or intermittent crank or camshaft sensor - anybody had issues with either?

[Welly]

I had a one-off crank sensor issue with my HDi once, engine sounded REALLY clattery and cut out, never happened again but that's the only thing we* could put it down to (no codes either) I think this sensor is pivotal to the running/idling in my mind. Maybe it can't throw a fault code because as far as the ECU is concerned the engine isn't running?

Please don't take that as a green light to travel to France again with a new CS because Welly said....

[Doggy]

Did you* change it, or did it mysteriously recover?

I suspect the ecu's processor isn't fast enough to fire the injectors directly and relies on some quicker hardware to do the actual control, using the crank sensor pulse train for timing and the ecu-calculated injection quantity plus correction factors for injection duration. In other words, the ecu wouldn't 'know' if the crank sensor was working erratically but would probably report a complete failure.

[Welly]

Never changed it no, it only happened once but it was a kinda 'dark' fault with no evidence. Or something.

Is it possible for the crank sensor to become contaminated and therefore intermittent?

I've got a curious image in my head (even more than most of the curious images in my head) of a stranded 406 estate at the side of some dusty track in that France...parked at a slightly inconvenient angle and fast looking abandoned.

[Doggy]

Close. It's in a farm yard, half hidden by long grass and an overhanging oak tree with a hedge on one side and an electrified cattle fence on t'other.
(The fence definitely works).

[Welly]

Sounds an ideal resting place

Leave a car for any more than 2 days here and it'll get smashed up by our nation of responsible* young people....

[dirtydirtydiesel]

Sorry to hear about your brothers tails of whoe Doggy
If it's of any help I'm quite sure it's the crank angle sensor
But it does also sound like the lift pump
All the best DDD.