S40 T5 Power loss, chugging and hesitancy but no lights

[brockie99]

I've recently been experiencing occasional bouts of a chuggy drive and hesitancy from the S40 T5 engine. I think it might be the Turbo but not 100% sure. When accelerating (not full whack) i get dips where you can feel the engine dipping and then picking up again, but other times its absolutely fine.

It got worse last night as when driving home and went to pull away from standstill, I got the car moving but then it died. By this I mean no power, with the car in 1st gear I was able to push the accelerator flat to the floor and nothing was happening. I started waiting for the engine management lights but nothing came up. Trying things to get the car going and stop holding the traffic up, I took it out of gear, put it back in first and then tried again and this time I had full power and was able to pull away fine. I then screamed the nuts off it in 1st, 2nd and 3rd to check it was working and it was then fine.

This morning all seemed fine on the way to work, so I'm baffled with what it could be.
I had the car serviced a few months ago so wondering if any filters might not have been replaced. One of my mates chirped up last night that it may be a blocked injector, but surely I would have lights come up with that?

Anyone got any ideas?

[iainmd]

Sounds rather like a problem I had 2yrs ago with my T5. Mine generally ran OK but sometimes (and mainly under load/heavy throttle) just cut the power for a moment to a second or so and then all was well again.

The first thing to do is get the diagnostic codes read. Mine gave (somewhat generic) error codes about fuel pressure warnings.

Volvo hadn't a clue what was wrong but when I desribed the issue to my local independent garage and they saw the fuel pressure codes they were 99% sure it was the fuel pressure regulator.

It was a £140 part unfortunately but it was indeed the culprit.

Hope that helps.

Iain

[brockie99]

Ah, that's very interesting. Thanks for the swift reply.

I have the car booked into an independent volvo garage next week, so will mention to him about the fuel pressure regulator and see what he thinks.

Don't mind paying that if it fixes the issue.

Just out of interest, did you have any warning lights flashing up on the dash when you had these problems?

Thanks for your help.

[iainmd]

I let the problem rumble on for 3 months and 3000 miles (including a trip to France) and it was about 2,000 miles into the issue before the emissions warning light came on. It stayed on for about the length of France and then went off again.

I was somewhat worried about it totally breaking down on the cross-channel ferry but thankfully it made it.

[t5_monkey]

Was it wet when you had this?

I had a similar problem a while back - but really it was just the road being very slippery and greasy, and the traction control kicking in.

(sounds daft - didn't notice the wheelspin aside from loss of power due to having the hifi on and not picking up on the change in engine note.)

[Miniguy]

I too had this problem on my T5, caused by the fuel pressure sensor giving a high fuel pressure reading, and therefore backing the pump off causing the hesitation. I managed to get a Bosch item (exactly the same) as the volvo unit for a more reasonable £95

[Welton]

There's also the possibility of the wiring being worn near the accelerator pedal (I think the clutch pedal can wear the wiring to the throttle wiring causing intermitant faults).

Let us know how you get on...

[brockie99]

Ok so the car's been in to the garage this week, had a thorough checking all over and they can't find anything.
Checked plugs, coil, throttle, oil, fuel pressure, injectors (i think) and nothing so far. This guy knows what he's talking about (ex volvo master technician I believe) and he's rather stumped.
They ran the diagnostics on it and although a fault code came up they don't know what it is or relates to. They then sent this diagnostics report off to Volvo, who have looked at it for 2 days and also have no idea what this relates to.
It would seem as though they have never seen this issue before.

I had a thought earlier on today, that perhaps it could be dodgy fuel.
Maybe clutching at straws, but seeing as I'm on the light at the moment, and about to fill up this afternoon, I'm hoping that putting some more fuel in from Shell may solve the issue. Unlikely I know but we'll see.

I'll keep you posted.

-- Forgot to mention that it was chugging alot again this morning in 2nd and 3rd gear under half to full throttle. Really obvious. The car was reasonably cold (one to two notches in from the left) so not sure if that's making it worse or not?

[don kalmar union]

It might be worth checking the pressure (MAP) sensor that is located on the exit (cool) side of the intercooler. Sometimes the connection can get a bit loose and that will give an effect something like you are experiencing.

Just get a hand on it and check the connection and whether it is in any way loose.

Regards, Don.

[brockie99]

Browsing around this site I see that other users were having similar problems to me with the hesitancy or 'oscillating' of power as one of the guys calls it.
I was looking at this thread:

http://www.volvoforums.org.uk/showthread.php?t=79064

and wondered if this could be the same as mine, seeing as we both have turbo charged engines? (ok so his is a diesel and mine a petrol, but could the issues be related?)

Now got a list of things to get my mechanic to check when I next see him thanks to the users on this site:
- Fuel Pressure Regulator
- Throtttle Body
- Accelerator Pedal Sensor
- Turbo Control Valve
- MAF Sensor
- Fuel Pump
- Turbo Boost Valve
- Boost Control Solenoid
- Turbo Pressure Sensor

Being a novice under the bonnet, I don't know if I've listed the same thing a number of times with different descriptions here, and was also wondering if any of these items actually do not exist on my car (T5 petrol turbo).

I suppose my mechanic could help me there.