P0087 rough idle and limp mode etc.

[Craigyd86]

2014 64 reg enterprise with 62k miles. 1.6HDi. Van started losing MPG so changed the fuel filter middle of January. Friday night it lost power and went in to limp mode with engine light and warning triangle “engine fault repair needed”. 
Scanned it with the launch, P0087- fuel circuit, pressure measured in the injection rail lower than the setting. 

So changed the filter for another new one yesterday. Still the same, hunting on idle a little until and the n it will settle, then a few hesitations on the throttle at lower revs when coming off the power and back on. MPG still brutal too. 

Fuel pressure sensor? Or drawing air somewhere? 

I had just filled it up the night before from a BP station. 

Today I took the fuel filter back out, checked for obvious signs of leaks, seal out of place etc and re-fitted then primed until the primer button got stiff and stayed down. Did seem a little better after this and drove home with a few little hesitations and the MPG back up to 54/55. 

Could it be dodgy fuel or am I looking at changing the fuel pressure sensor on the end of the rail? 

Next step is to take live date from the fuel pressure with launch? 
Cheers.

[Sol]

I'd start with live fuel pressure readings. The HP pump pressurises the rail under control of the engine ECU with feedback from the rail sensor. So if it's saying fuel pressure less than commanded then either the sensor data is bad or the HP pump is faulty perhaps.

Idle pressure should be around 300 bar, max under full load is around 1500 bar (multiply those by 14.4 if your launch reads in PSI).

Doesn't explain the poor mpg but is that definitely bad from known miles covered vs fuel used or by the mpg display? If fuel pressure and flow are measuring wrongly then the display will be meaningless.

If it's genuinely bad on fuel and eating it, then it has to be over-fuelling massively but not realising it's doing it. The dpf will hide any smoke so it won't be obvious to you.

So my guess is the rail sensor is reading really low, ECU ramps up the rail pressure to compensate, trying to hit the requested value. Thinks it can't, so throws the error. Meanwhile chucking buckets of fuel at the cylinders and down the exhaust. If it's over-fuelling all the way through the rev range you're probably accumulating a lot of soot in the dpf and your oil will get contaminated with diesel.

One last thing, it doesn't have a tuning box fitted does it? If so and it packs in, could cause exactly this issue.

On mpg, I get an average of 43 on longer motorway runs when the van is empty. Running around in town, it does 33. Never seen anywhere near 55 ever.

[Craigyd86]

Thanks for the reply that’s usual info to take onboard. 

Using the launch to check the pressures is my next step so good to know the values. 

Van is completely standard with no tuning box/re-map etc.

Only other issues/reasons I can think of is it was between -15 and -9 for the whole day previous to it playing up and also -3/4 when it threw up the light and errors. 

Usually get around 600 miles to a tank of 40miles to work and back each day (20miles each way)

[Sol]

Yeah it has been bitter of late. Not sure if your IAT was causing EGR mischief with the low temperature, that might explain the lumpy cold idle but not the fuel pressure fault code.

Have a read of this document - explains in detail the entire 1.6 HDi engine system functions with the EDC17C10 ECU, sensors, actuators, EGR maps, test values etc. Could give you some pointers and it has excellent info in it. I posted it earlier in the tutorials section:

https://www.berlingoforum.com/thread-20567.html