EGR Fluctuating

[jimmymarsbar]

307 2.0 HDI DW10ATED RHS Engine

I had the timing belt, water pump, thermostat and temp sensor replaced at a garage a couple of weeks ago, and to cut a long story short, I also had to replace the turbo wastegate solenoid valve, as the mechanics had damaged it. I bought the valve from a breakers, and tested it by sucking on the inlet, all seemed ok.

Since the belt/pump/valve was replaced, the car has been sluggish through the gears, but the turbo kicks in as normal around 1800rpm. When I say sluggish, there's more power compared to when it would go into limp home mode (such as getting to the breakers without a boost valve!), it just struggles to climb up not-too-steep hills in 4th, whereas normally it'd fly up them.

I've plugged into PP and there were a few errors on the engine management ECU, and it looks as though most of them were due to the coolant system components being disconnected/disturbed.

So I had a look at the live data with the engine running. First thing I noticed that the turbo pressure was 121 mbar less than the reference value at idle, and the turbo "position" was steady at 88%. Secondly, and probably more importantly and relevant to the post, the EGR position was fluctuating wildly between 45 and 60%, with the occasional jump up to 70ish.

I did have a fault code relating to the MAF sensor open circuit, but a visual assessment is all ok, and I put this down to the intake manifold being removed to get to the stat and sensor.

So, as I am looking at things, something is telling the EGR to change it's aperture size frequently and randomly. What I don't want to have to do is remove the EGR valve, as it's a pig of a job on this car! I'm hoping that the something along the lines of intake air is causing the EGR to fluctuate as much as it does.

Could part of the issue be the EGR going through a "learning" process, as I have replaced a vacuum valve?

It might be worth noting that, on PP, it's showing that the car is trying to regen, but has been unable to do so, probably because of the coolant system fault codes. The DPF condition is logged as "intermediate", so whilst it's not blocked completely, there could be a blow back of additional exhaust, thus causing the EGR to open more often.

Or am I missing something?

[Gibbo2286]

I'd swap the MAF if the diagnostics hint that there's a fault there.

[jimmymarsbar]

Cleared the fault codes after the car came back from the garage, and they've not returned yet, so I reckon they were due to disconnecting the sensors.

On Friday I got "Diesel Filter Blocked" on the dash, so I reckon that's what's causing the lack of kick in the lower rev range. Already got the filter which is handy, I just need to work out which fuel line feeds the filter. If I remember, does the filter get a feed from the tank and HP pump?

[RichardW]

Diesel filter blocked will refer to the DPF not the fuel filter....

Normally the fuel filter is just a feed from the tank, and then onto the HP pump - the earlier HDis had a heater as well, so there were extra pipes, but there are only 2 on the 1.6 HDis, don't know about yours specifically.

[jimmymarsbar]

Thanks Richard, sounds like it's time for an Italian regen

On the subject of fuel filters - the last time I had to give it some attention, I had a bit of a mare with fuel spurting everywhere. The housing has 3 pipes attached - one at 9 o'clock, on at 12 o'clock and one at 3 o'clock (as you're looking from the front of the car).

One runs from the tank, one to the HP pump and the other to the rail (please correct if I'm wrong). When I was last priming the fuel system, I had fuel being ejected from each pipe and outlet (from the housing).

If I wanted to replace the fuel filter (as it's on my to do list), Haynes vaguely tells me to disconnect the outlet pipe, but I've got a selection of 3......

Any pointers to which of the pipes they'll be referring to?