2004 1.9 DCi Flat Spot / Loss of Acceleration

[MikeLB]

2004 Megane 1.9 DCi - 105,000 miles (yes, 105K!)

Bizzarre Flat Spot appeared just after the last service as about 94K miles. Complete flat spot when accelerating from about 2600 rpm, once you get it just above 2800 rpm it picks up again no problem.

Problem has got worse over past thousand miles though, with 6th gear almost useable for any acceleration. If you hit the lsightest incline in either 5th or 6th, the power lietrally dies. Foot to the floor and nothing happens. Drop to 4th, get the revs up, its all good. 6th is fine on the flat. The Flat Spot range has widened to 2600rpm to about 3000rpm

Not convinced the turbo is faulty as when it kicks in its still pulling very hard.

Dropping down the gears seems to work to keep the revs high and strangely, my fuel consumption has improved a lot too!

Its due for a service in 1000 miles anyway so its liveable - after all its been like this for the past 16,000 miles, but any ideas of anything I could tinker with myself before hand and keep the costs down.

Clean EGR for one?

[IainMW]

As you say EGR is one to look at straight away.
https://www.meganeownersclub.co.uk/forum ... .php?t=155

At this mileage, you can't dismiss Turbo problems Can you see any traces of oil around the turbo?

If it has been doing this for the last 16000 miles and it does turn out to be a clogged EGR valve there is a big chance that the Turbo will have suffered as a result

Other than that it could be a number of things. I would seriously recommend you get this checked out ASAP.

[MikeLB]

EGR cleaned (it was surprisingly clean for the mileage to be honest and freely moving before I cleaned it) and made no difference. But it did develop into a more major problem today with total loss of acceleration ability - It was due a service in 7 days anyway so not a major headache.

It almost feels like its being starved of fuel / air - You have to keep revs up at over 3000rpm to get it moving at all, Stalling trying to get it out of the gravel drive, doesnt idle very well, engine sounding very clanky all of sudden.

Starting to look more like the TDC / Air flow meter issues?

[graeme]

I had this problem on my laguna DCi.

It was the turbo that was the problem, oil seals were bugger so the turbo was leaking oil. and it was getting to hot which knackered the blades in the turbo or something like that. is it pre 2003 by any chance ?

[MikeLB]

Well thats it sorted - quite an intriguing one this time.

EGR Valve had split into two pieces, with part of it falling into the Manifold. This was diagnosed and repalced, but didn't cure the total inability for the car to take acceleration.

Fuel pressure etc was all ok. Turns out that because of the EGR Failure, the manifold had almost completed blocked up with carbon. So they cleaned it out and bingo - all sorted.

Was less then impressed with Ness Motors in Inverness this time though who seemed to be insisiting on a complete new Cat System as well before working out it was even the manifold. Thats another story but there approach to problem diagnosis was a bit wayward this time - opting for the replace and charge method as opposed to lets work it out properly first before we give a quote!

Total cost - £488 - so quite happy really. And it is pulling through all the gears like never before!

[IainMW]

£488

I would not be happy to pay for something to be replaced that did not need replacing. Why did they replace the CAT?

As the EGR is such a common fault on the early 1.9dCi engine they should have known to clean the manifold when replacing the EGR valve, this is a standard proceedure and should have been done when the valve was replaced.

[MikeLB]

What i forgot to mention when I re-read that was I also got fuill service done - oops.

I didnt let them replace the Cat until they gave a proper diagnosis, which was the manifold. So that saved a few bob!