Vaux 1.7 CDTi help

[Ian Geary]

Morning

it's a cruze 1.7VDTi, but it's identical to the 130bhp engine in the Astra J and Mokka I believe. 63 plate, 130k miles.

brief background:

- was getting limp mode P000F - fuel system over pressure in February. On the basis of starting simple and cheap, I changed the suction control valve (on the back of the HPFP) and this problem went away. Here's a link to the sort of thing I changed

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- a few weeks later, we're getting limp mode again, with a "service vehicle soon" message. Limp mode is pretty hairy on the M-way or trying to pull across a busy A road for example.

- code is now P228C - Fuel Pressure Regulator Control - low performance


I had a fuel filter to change anyway so did this last night. The problem has not re-occurred "yet", but I was on the school run so hardly the chance to test it thoroughly.


This fuel filter change has however given rise to some further issues / queries this morning, which I would be grateful for any help with?


Question 1 - after doing the paper type fuel filter, the car doesn't start quickly. Three times now it's needed 8-10 seconds of cranking before it catches. It has always started on the button. If I restart quickly after turning off, it's OK. Battery is fine.

Is this likely to be related to the filter change? Should they have non return valves to keep the fuel in the filter? Does anyone recognise this symptom?


Question 2 - my Autel digilink tool can track fuel pressure. As soon as the engine is off, the sensor fuel pressure falls to zero in about 10 seconds. Even with the ignition remaining on, the car does not build up fuel pressure. Is this normal, or should the system retain pressure longer? (I suppose its OK, as the HPFP is cambelt driven, so it can hardly pressurise without the engine spinning.)


Question 3 - desired fuel pressure vs fuel pressure sensor: enlisting my kid's help to watch the Autel reader, we can see there are some variances between these 2 readings, though they broadly move in step. What sort of difference / tolerance should be expected here?


Question 4 - the engine definitely stumbles when coming off the gas. This corresponds with "sensor" fuel pressure falling quite far below the desired fuel pressure in these events. Eg "desired" fuel 25 MPa, "actual" dropping to 17 Mpa briefly.



All in all, it's a £2.5k car, but it's worth more alive than dead. I have ordered a HP fuel rail sensor (£30) but the next item to be loaded into the parts cannon will be either a HPFP or the powertrain control module. Both of which I'm reluctant to do with out more diagnosis.



thanks

Ian

[stevieturbo]

1. After a filter change, you must ensure the housing is as full as you can get with clean fuel ( and also clean out the housing before fitting the new filter )
Do not fit it dry, and do not continually crank the engine over for ages to try and make it start. It will cause harm over time.
Or better still add a manual pump so you can bleed/fill the system manually before starting.

2. You cannot create pressure if the pump is not turning

3. You need to datalog/graph them to really see. But they should be fairly close. With some scan tools their slow refresh rate could be a reason for discrepancies, so the tool needs to be able to log at a decent rate, even 10Hz would be fine.

And also record with the "suction" valve is doing, and any FP response to it to see if it is working ok.

4. When you let off, fuel would be shut off, there would be no need for pressure in the system.


How dirty/clean was both the filter and fuel in the housing ? and housing ?

I had one once, where some idiots had worked at it and alleged pump and all sorts had been replaced. One thing they clearly did replace was the pressure relief on the main rail, except they rammed it in so hard it mushroomed the end of it, rendering it scrap. They had been trying to trace some sort of problem...and failed.
Ultimately I bought it in a middle state, and a short time later pretty much entire system had failed, metal throughout, fuel ended up filthy. I had to change the entire fuel system. And that was a low mileage vehicle, less than 30k at the time, albeit 12 or so years old.

[Ian Geary]

Thanks for replying.

The filter was dirty, but not overly excessively so I think



The diesel I drained seemed ok, though it went into a tub that wasn't clean, so hard to be sure.

The filter assembly screws up from underneath, so I couldn't fill it with fuel beforehand. But I could have left the in tank pump a bit longer to prime it I suppose.


Anyway, did 100 odd gentle motorway miles today, and it's starting fine, and not hitting limp mode when accelerating.

I will need to test it out in various ways, as it's too early to tell if the fuel filter has fixed the fuel pressure regulator - low performance error.

I think the dodgy starting was just the lack of proper priming.


Ian