Sporadic cutting out and losing power

My wife's car is a Fiat Ulysse 2.0 EL petrol (year model 2000)(same as Peugeor 806). The motor cuts out sporadically while driving. Even stationary at constant revs, the revs drop right down at times. It has now become so bad that the car is undrivable. (No power at times) I Have checked the following:
There is no water or dirt in petrol tank, Filters are OK, Fuel pressures seem OK, a specialist checked ECU and said it is OK (I'm still not convinced), Have
checked electrical connectors.
Any bit of advice will be much appreciated at this stage, as there are very
few of these units in South Africa and no one seems to have any experience
with such a fault.

Hi Stephan
We had this problem once it would stall for no apparent reason and losing power or Chugging. The fiat dealer tested the ECU and reported "No fault found" He cleaned up some of the contacts on the ECU as there were signs of corrosion and it has not chugged since but now and again it stalls instead of idling normally from cold and cleaning the idle valve and chamber seems to have made a difference, and once just disconnecting the ECU spraying WD40 and reconnecting solved the immediate problem. It is worth checking other Threads mentioning idle problems if not already done so.
Best of luck.
donald.

Hi Donald,
Thanks for your reply. It all made a lot of sense, but surely the dealer would have done this? Not having anything to lose, I unplugged the ECU and sprayed some switch cleaner on the contacts. For good measure I cleaned and sprayed the contacts of the relay ?! next to the ECU as well. Not expecting much, I went for a quick 20 km test drive with no cutting out.
If it starts up again, we'll just have to Fix It Again Tomorrow!
Lets hold thumbs it lasts. Thanks a lot.
Stephan

I don't think the dealers will take the ECU out to test. They just plug the car into a computer and read any fault codes.

Hello Everybody,
It is me again. The advice Donald gave me worked for few days. Now it,s back to its old tricks again. The ECU was removed and taken to a specialist, who pronounced it OK. I have cleaned and sprayed every electrical connector in sight (Last time I thought this had solved the problem) When stationary with the revs at 3000 it drops down to about 2000 momentarily before going back up to 3000. During the spells when the revs drop, one can feel that there is no power.
Driving it is virtually impossible at this stage.
Thank you for all the advise so far.
Stephan

Hi Stephan,

Does the car only cut out when idling or when changing down gears?

Darren

Hi Darren,
The car cuts out as it goes over 2500 rpm, whether stationary or driving. It does not seem to make any difference as to whether the motor is under load or not. It seems like it might be a faulty knock sensor. I have been testing the car with this disconnected and it seems fine. (I just want to make sure that this is causing it, before ordering a new one.) Any additional info will still be useful, as it might still be something else! I will post the final finding as soon as I'm convinced it is sorted out.(hopefully soon!)
Thanks for the interest.
Stephan

I presume the engine isn't actually knocking is it?
I think the Knock sensor is supposed to detect "pinking" but it's possible it could be picking up a mechanical "knock" instead and getting confused.
Still a new sensors not the end of the world in terms of cost and can't think what else to try.

Sounds verymuch like a faulty body computer to me, take it into your local dealer and get them to plug it in for a diag.
usally this cost about 35 pounds plus vat

Some dealers charge £70 plus VAT - barter, best way