2005 S40 T5 cutting out

[whatsupdoc]

Recently bought a S40 T5 with 117000 km on it. The car runs perfectly but after about an hour or so driving suddenly loses power and/or cuts out completely. after cutting out whiule coasting out it will suddenly jerk violently as if the engine is agin giving full power for a moment. After cut out it will restart and tghen seems normal again for a while. After the first time it happened it briefly showed the emission control warning light, but not again. Have checked both Lambda sensors and replaced one so far that looked dodgy. Gave a general service including cleaning throttle body, airflow sensors etc. Ran well for the first 2 hours then started again. Feels like either the fuel supply is being interrupted or the throttle is closing itself. Had it on a computer - no error codes show. Any suggestions help would be appreciated! Thanks

[iainmd]

That sounds similar but more prevalent than the issue I had with my T5 a year or so ago. With mine it was the fuel pressure regulator that was at fault.

Mine would drive normally then for a second or more completely judder and lose power then return to normal operation again. Sometimes it would do it constantly throughout a journey and other journeys it would be OK. When it happened the shudder through the car was quite violent. The emissions warning light was on for some of the time but not all.

The car showed no fault codes apart from rarely one about fuel pressure being low.

Cheers,

Iain

[iainmd]

Forgot to say I also had the throttle body cleaned and the Fuel Pump Electronic Module replaced and that did nothing to sort it. Volvo replaced the latter FOC even though the car was out of warranty as in certain cold weather countries they've issued a recall on it but not in the UK.

The new Fuel Pressure Regulator was about £140 for the part.

[whatsupdoc]

Thanks for the advice Iain. Will definitely check that out. Do you maybe know how they diagnosed the problem / tested the pressure regulator? Because there are no error codes we are currently looking more for mechanical type problems, like either a blocked fuel tank breather, or maybe dirt in the fuel tank causing a partial blockage of the pump strainer etc.

[whatsupdoc]

Follow up. We dropped the fuel tank and found the fuel pump screen almost entirely blocked with a blackish substance. Other than that the tank was not very dirty. But it seems likely that we may have found the problem. Will post if successful

[iainmd]

The Volvo garage kept plugging it into diagnostics which brought up a very rare 'low fuel pressure error' but it was rare!

The independant that fixed it listened to me describe the problem and instantly said "fuel pressure regulator, I guarantee you". He was 100% right. You can't beat a proper mechanic.

[whatsupdoc]

Well cleaning the fuel filter inn the tank did not help! But when the problem occurred again at least the engine fault light stayed on which I assumed meant it had stored a fault code. So took it to Volvo for a computer diagnostic check.

This is what they say needs to be replaced!!!
Fuel pressure regulator
Fuel pump
Rear O2 lambda sensor
Turbo control valve
Vaccum control valve - something to do with the brake vacuum pump running continuously?
Software upgrade
Total cost about ZAR 14500 (approx UK 1000).

I flipped as this sounded like they are guessing and have just decided to change everything that MIGHT have any bearing on the problem. IF the car really has all these things wrong then it will be the last Volvo I ever buy. Based on Iain's experience I have told them to change only the fuel pressure regulator. Will see what effect this has...

[bigjohn]

i sympathise and know how you feel .

[Clan]

Originally Posted by iainmd

Forgot to say I also had the throttle body cleaned and the Fuel Pump Electronic Module replaced and that did nothing to sort it. Volvo replaced the latter FOC even though the car was out of warranty as in certain cold weather countries they've issued a recall on it but not in the UK.

The new Fuel Pressure Regulator was about £140 for the part.

Yes it was a recall in the UK , the PEM was renewed and moved to a dry location under the back seat , so if your PEM is still under the car at the right rear go for the mod ... it's likely to be corroded inside ..

[Guru]

Originally Posted by whatsupdoc

Turbo control valve

Software upgrade.

I would tell them to do these two first and then go for a test drive before continuing with the rest, you could end up saving a lot of money.

The TCV is a cheap and easy to replace component that is often overlooked by mechanics in both diesel and petrol engines alike, but can cause all the symptoms you described and a lot more, even the "limp home" mode during or immediately after an aggressive overtake is most often caused by the Turbo control valve, but the poor EGR valve "in diesels" always gets the blame first for some reason or another, although the TCV sticks out like a sore thumb in the engine being it the only brown semi-cylindrical plastic component in an otherwise black engine bay enviroment.