Almost total loss of power

[Gregory Guineapig]

I have a 2004 V40 diesel Sport estate. It's always been very responsive and quite quick.

Some time ago, the idle got lumpy, but seemed to clear a bit after a while. Then the low revs acceleration dropped off, and soon got to the point where nothing happened until about halfway between 2000 and 2500 revs. Then there would be a short burst of its old power until about 3000, then flat as pancake again. Now it has even lost that narrow band of power. With my foot on the floor, in second gear, it will eventually get to about 3500-4000, but nothing more and feels like an old lorry with a governor set to low revs. Fuel consumption gone up.

Italian tune-up impossible, and embarrassing/dangerous when pulling out of side road.

One last thing, I can't hear the turbo at all (I used to be able to hear it faintly when winding up), so assume that's the problem.

What is the best way to proceed?

[LTEcactus]

Originally Posted by Gregory Guineapig

I have a 2004 V40 diesel Sport estate. It's always been very responsive and quite quick.

Some time ago, the idle got lumpy, but seemed to clear a bit after a while. Then the low revs acceleration dropped off, and soon got to the point where nothing happened until about halfway between 2000 and 2500 revs. Then there would be a short burst of its old power until about 3000, then flat as pancake again. Now it has even lost that narrow band of power. With my foot on the floor, in second gear, it will eventually get to about 3500-4000, but nothing more and feels like an old lorry with a governor set to low revs. Fuel consumption gone up.

Italian tune-up impossible, and embarrassing/dangerous when pulling out of side road.

One last thing, I can't hear the turbo at all (I used to be able to hear it faintly when winding up), so assume that's the problem.

What is the best way to proceed?

It could be a sensor issue, affecting how the engine runs.
I would definitely plug it into Vida and see what error codes you get.

[gatos]

Check all the vacuum hoses, turbo and intercooler hoses for a leak. you can also unplug the MAF sensor and see if the car runs any better. Also, it's worth removing and cleaning the EGR valve, as it gets blocked with soot. If none of the above sort out the problem, the other thing I can think of, is the N75 valveon the bulkhead.

[Gregory Guineapig]

Thanks for the advice.

New dimension.

I had to use the car this morning. Limped along for about 5 miles, then had to wait at a junction. When I finally decided it was OK to go, suddenly I had full power again. It was as if somebody had turned a switch on.

Drove about 8 miles, still with full power. Parked for about an hour, started up and back to limping!

Electronic problem? Although the engine management light hasn't come on. What does the N75 valve do? Is the MAF sensor the one fitted into the air intake hose?

[Gregory Guineapig]

Just disconnected the MAF sensor and its back to full power.

Can I clean the sensor, or does it need to be replaced? Or can I run with it disconnected?

Very grateful for your help gatos and LTEcactus. You both pointed me in the right direction. Big relief.

[gatos]

Originally Posted by Gregory Guineapig

Just disconnected the MAF sensor and its back to full power.

Can I clean the sensor, or does it need to be replaced? Or can I run with it disconnected?

Very grateful for your help gatos and LTEcactus. You both pointed me in the right direction. Big relief.

Either the MAF is dirty or faulty or one of the other sensors might be misbehaving. By disconnecting the MAF, the car's ECU goes on default and uses default map to run. So, you could try using some electrical contact cleaner and spray the MAF to clean it and see if it makes a difference.

Ideally, get the codes read and see what comes up. If it is the MAF that is faulty, then either buy a genuine Volvo or Siemens one, new or second hand. Don't waste your money on those cheap Chinese rubbish ones, that use a simple resistor to imitate the operation of the MAF, because they will work fine in the begging and after a while, the car will start running like crap again

[P156KWJ]

Originally Posted by gatos

Either the MAF is dirty or faulty or one of the other sensors might be misbehaving. By disconnecting the MAF, the car's ECU goes on default and uses default map to run. So, you could try using some electrical contact cleaner and spray the MAF to clean it and see if it makes a difference.

Ideally, get the codes read and see what comes up. If it is the MAF that is faulty, then either buy a genuine Volvo or Siemens one, new or second hand. Don't waste your money on those cheap Chinese rubbish ones, that use a simple resistor to imitate the operation of the MAF, because they will work fine in the begging and after a while, the car will start running like crap again

I second this, I bought a HAAS branded MAF from Euro Car Parts and it ran worse than it being unplugged. To add insult to injury I managed to break it taking it off because even the plastic was nasty so I couldn't even take it back, ended up in the bin.

Last year I managed to get a secondhand one from a local Volvo breaker for £20.

Volvo themselves wanted something ridiculous like £200 for a new one, however Renault were a much more reasonable price (around £70-80). Some new genuine ones on eBay too, same Siemens product.

Volvo part number: 30887504
Renault part number: 7700109812

[Gregory Guineapig]

Thanks for the part numbers

[V40DSchariot]

Been an age since i've been on here as i've updated to a V60 D4. I must say it's great not having to do much to it! Having said that I do have a 2000 T4 sat there waiting to be sorted.
Anyway, I had a problem with my 2003 V40 diesel a few years ago and tried all the normal stuff, all worked for a very short period but the problem always came back with the lack of power.
Take a look at this thread I did at the time, nobody seems to have suffered the same issue but it was frustrating until I found this problem.

https://www.volvoforums.org.uk/showt...=179816&page=3

There is a shut off valve when turning the ignition off that uses the excess vacuum to shut off the air supply when switching off, this valve was open to atmosphere when running, meaning there was no vacuum, meaning engine runs like Sh*t.

[Gregory Guineapig]

Originally Posted by V40DSchariot

Been an age since i've been on here as i've updated to a V60 D4. I must say it's great not having to do much to it! Having said that I do have a 2000 T4 sat there waiting to be sorted.
Anyway, I had a problem with my 2003 V40 diesel a few years ago and tried all the normal stuff, all worked for a very short period but the problem always came back with the lack of power.
Take a look at this thread I did at the time, nobody seems to have suffered the same issue but it was frustrating until I found this problem.

https://www.volvoforums.org.uk/showt...=179816&page=3

There is a shut off valve when turning the ignition off that uses the excess vacuum to shut off the air supply when switching off, this valve was open to atmosphere when running, meaning there was no vacuum, meaning engine runs like Sh*t.

Thanks, will investigate.

The diagnostics couldn't find a fault, so at the moment I am running with the MAF sensor disconnected. And its running really well ... although fuel consumption seems to have gone up. Used to average around 50 m.p.g. according to the dashboard display (47 locally, 50+ on a run). Now less than 40 locally.