Hi all,

I've been working on this 2009 Ford Fiesta for a while now with a 1.6tdci engine. I've managed to fix most of its problems however one has left me scratching my head.

When the engine is cold if I start the engine the revs will bounce around for about 5 seconds, but after this it maintains a steady idle. However if I bring the revs up and let them come back down, it will be fine for a moment, then almost stall, then recover and be fine again. After about 30 seconds when the engine has got a bit of warmth these problems go away and the car will drive perfectly well. I should also point out that if I bring the revs up during this time period it will feel like the engine has a misfire.

If I connect my scanner to the engine whilst it is cold, I can see that when the revs come back down, the fuel pressure drops too far, then suddenly comes back up and the engine recovers. I have also noticed that when I turn the key off the fuel pressure drops off quickly to zero (after about 15 seconds).

I thought this was an injector problem so bought another one and started swapping them around, however this had no impact. I did not change the injector codes whilst I was doing this, so could that cause a problem?

If anyone has any advice it will be greatly appreciated.
Thanks.

Idle control valve ?

Hi,

I was thinking that although apparently diesels don't have them.

Doh of course,if its not a blown fues for the glow plugs or relay , then i suggest EGR Valve could be clogged up.Take aprt and have a look.if it is this every now and again put additive in the fuel keep everything clean.keep us posted on out come.

Does sound like Glow Plugs to me too, try popping them out if there completely black they need changing. 

Thanks guys will give the glow plugs a look. I should also mention I changed the EGR valve recently however it had no effect.
I've heard this could also be the fuel pressure regulator, does anyone agree?

Hi Mate, is it something similar to this?

https://youtu.be/zbdPA6DjK9Q

Hi, not quite. When I turn the key it fires pretty quickly and the needle jumps up, but bounces around for a while before eventually settling.
Just looked at fuel pressure and it bounces around a lot.

Just been out again with my scanner, and found out at idle the fuel pressure is around 200 bar (seems a bit low?) and that even when the engine is running at constant RPM, the pressure will bounce from around 180 bar to 220 bar. When I press the accelerator the pressure increases quickly, however when it drops back down it drops very low, to around 120 bar, where I feel the engine judder, then bounces back up to 200 bar.
When the engine is running there is also a lot of vibrations in the cabin.
Hope this helps.

Fuel rail pressure sensor if one fitted ?

Unfortunately I've already replaced that but no luck.

Pressure check it from the pump

How would I do that?
Thanks

To help anyone reading this in the future, it turned out fuel pressure was not a problem as the engine is meant to have 200bar at idle.
The actual problem was that the connectors on the EGR plug were loose and not making proper contact, so even after replacing the EGR the problem still remained.
All it needed was a new wiring plug for £10.

Honestly, I have just purchased the same car and I am having the same issue, I am going to try and solve it myself this weekend to see if it is that. 

Apart of the issues described (the uneven idle when cold and the shaking in the cabin) i must say that the faster you go, the more you feel the vibration to the point that at 70mph if I let the steering wheel go, you can see it shaking like a f***er.

Another thing I realized us that it didnt have as much power as I was expecting for a 1.6 turbo diesel, before this one, I had a 1.5 clio (no turbo and diesel) and that seems more powerful to me so lets just take a look at the weekend.

Cheers pals!!! Very helpful

Kev