No umph! C5 mk 2 2004 2.0 hdi manual

[mickthemaverick]

While I agree that clogged up intercooler or turbo piping etc will cause loss of power and poor running I don't see how disconnecting the MAF would restore perfect running under those conditions. Or am I missing something?

[MikeT]

Without an accurate airflow (MAF) reading, the engine management will resort to a backup strategy.
It may therefore be overfuelling - great for power but not so good for emissions and reliability.
It may also ignore/disable a number of other air/fuel-related components, masking the original symptom(s).

If you're confident the MAF (and it's wiring) is not faulty, then start suspecting other relevant parts of the air/fuel controls.

[myglaren]

I have got some brake cleaner, and I intend to soak the intercooler in that. As Michel said, we did give it a clean out, but what did come out was not very liquid (as nothing came out when it was taken off the car), and when we mixed engine degreaser, washing up liquid, Harpic 10X and hot water (and left it for 10 - 15 minutes) what came out was black and gloopy. Repeats (until we ran out of degreaser) had similar results, so, despite getting a load of crap out, there may still be a load in there (setting a bit like tar).

Should have put it in the dishwasher, I'm sure Mrs Michel would have been ecstatic

[Hell Razor5543]

I have got some brake cleaner, and I intend to soak the intercooler in that. As Michel said, we did give it a clean out, but what did come out was not very liquid (as nothing came out when it was taken off the car), and when we mixed engine degreaser, washing up liquid, Harpic 10X and hot water (and left it for 10 - 15 minutes) what came out was black and gloopy. Repeats (until we ran out of degreaser) had similar results, so, despite getting a load of crap out, there may still be a load in there (setting a bit like tar).

Should have put it in the dishwasher, I'm sure Mrs Michel would have been ecstatic

And I would be at the morgue!

[myglaren]

[GuzziG]

Hi chasqui, I had this issue with my Mk1 C5 [03/110PS]. If all mechanical/MAF/sensor faults have been checked and eliminated then I would suggest the following. The Citroen versions of these engines are totally drive-by-wire, and as such the ECM operates under an adaptive learning strategy. If the previous owner was very sedate/not throttle heavy then the ECM has "adopted" this drive style. My C5 would not accelerate hard and 'choke/stall' up gradients etc, making me go through the same MAF/sensor/pain-in-the-arse issues you have. Because the throttle pedal is only a sensor you have to adjust to being really aggressive with it [at least for a while]. Once I'd learned to stick the boot in [unlike throttle cable equipped vehicles] it began to adjust. After about 4-6 weeks with a lead foot it was as good as gold. Unexpectedly you also get massively improved fuel economy!

[myglaren]

That's a thought!
Mine was seriously rubbish when I first bought it.
Had all the pipes & EGR cleaned and the intercooler replaced -it was holed and full of oil.
The thing that made the biggest difference was adjusting the throttle cable.

Some have the TPS in the pedal but others, mine included, have a cable between the pedal and the TPS which is in the engine bay.
Mine is an 03 too.

[mickthemaverick]

Good thinking Guzzi, isn't there a method of resetting the learning and starting from scratch?

[mickthemaverick]

Just got back from a trip to see Chasqui and I can tell you we found two suspects. Firstly an over squashed bend in one of the MAF wires which we spliced out and second a poor fitting joint sleeve on the EGR vacuum feed which we remade with a tape padding. The car is now running with MAF connected and full power restored!!
All's well............

[chasqui]

Resolved!!!!
Following a visit from Mickthemaverick who battled valiantly through the M25 traffic to reach me...

I have a new car again! Thank you Mick and to all others who offered help/advice.