V70: Engine My V70 D5 runs like dog one day and a thoroughbred the next

[N11BOT]

Originally Posted by tt82

Yeah, my 185bhp D5 loses a some MPG after I come off the motorway and have to accelerate away from lights, though I don't boot tit hat hard I dont dwadle either.

Have you considered resetting the Info center whilst on a motorway doing 70mph and see what it averages.

Funny enough I did exactly that today on cruise control and it produced 44mpg over 6 miles flat run @ 70mph. So perhaps its the right Podia that needs attention.

My wife is a fountain of knowledge one everything one can imagine and some topics unimaginable too (her specialist subject is: knowledge after the event). She suggested I got into the habit of using the cruise control whenever reasonable and kept my tyres at the correct pressure - cannot argue with that!

This does not mean however that the car's intermittent habit of occasionally - for a period of time, days sometimes - feeling gutless in comparison to usual is not an issue. It is.

[SonyVaio]

I get the feeling your problem lies with your DPF and the pressure sensors.

The running lumpy along with the drop in MPG sound like they go hand in hand and will most likely be because the car is undergoing a 'Regen Cycle' for cleaning out the DPF, the DPF uses excess fuelling to achieve this. On the exhaust strokes of the engine it injects fuel and thus uses more fuel and MPG drops.

If the pressure sensors are faulty it will be causing excess regen cycles as the car thinks the DPF is blocked and requires cleaning.

You would do well to have the car error codes read properly by VIDA/DICE (great if the indy has this but if not seek Volvo assistance or from a member with VIDA/DICE) once codes are known it should point in the right direction.

All in all I believe your problem to be either blocked DPF or pressure sensor problem causing excess regen cycles.

[N11BOT]

Originally Posted by cloggers

I have exactly the same issue by the sounds of it...

I have a 59-plate 175ps 2.4d and last December it started to have moments where it didn't have any oomph, like the Turbo was not kicking in. When the car said something like 'Engine system service urgent' I called the Volvo roadside assistance.

The helpfull man from Volvo reset the fault code and could not find any they car seemed to work ok again until a week later when it came back and I dropped it off at a dealer near my work. The replaced some kind of sensor (was it temperature?) and the car ran like clockwork again.

Small note: the Volvo garage appeared to have more fault codes / better equipment then the volvo roadside assistance - would this be why your independent can't find it? Because Volvo has a special diagnostic tool for authorised dealers?

Anyway, the problem has returned. The engine has gone back to some kind of fail safe mode and have less power than a 1.6 litre engine...

I will go back to Volvo next week to find out what they say. Please share your findings if you have any updates as I am very interested!!!!!

Ps: Clan, if you are online I would really appreciate your experience on this...

My wife's XC70 185bhp 08/08 74,000mls has recently suffered the same sounding issue. Very substantial reduction inn performance. That was producing fault codes to show the EGR (exhaust gas regeneration) value was operating faultily.

The independent Volvo guys wanted to replace the value and is was a 2hrs job with 250 parts so I had a good ring round specialists and found little help but for www.bridgendvolvospecialists.co.uk Jason who said yes its sounds like an EGR valve but it could be the control unit.

So my Independents change the control unit £110 plus 2hrs and the car is driving better than ever since purchasing 2yrs ago at 45,000mls.

What is interesting is the amount of very sticky black tar like substance they removed from the system. I am doubtful any components were indeed faulty. I think the EGR valve becomes clogged with residue and become jammed open - that woiuld account for a substantial loss of power.

Indeed it could also start to partially fail to close and that too would cause power loss/poor consumption. This is my 'theory'!

A solution could be to use a diesel additive! OMG

I have been looking into the prospect of using Millers Diesel Power Ecomax 500ml but am CONCERNED that this could be risky! It my be harmful to the DPF - certainly Volvo do NOT recommend using diesel additives but it is easy for they to say that - play safe - whilst not training their dealer service network how to solve this issue.

http://reviews.halfords.com/4028/811125/reviews.htm
http://www.halfords.com/webapp/wcs/s...egoryId_255221

I am also considering using a BG product.

See: http://www.halfords.com/webapp/wcs/s...egoryId_255221

http://www.bgprod.co.uk/AutoProducts/Fuel&Air/211.htm

This is scary stuff - could be an engine killer! I am looking for a willing dupe to test it out on their car first: Any takers!

[krzemien]

Originally Posted by cloggers

I have exactly the same issue by the sounds of it...

I have a 59-plate 175ps 2.4d and last December it started to have moments where it didn't have any oomph, like the Turbo was not kicking in. When the car said something like 'Engine system service urgent' I called the Volvo roadside assistance.

Just for the record: I had the same problem with my very similar car in April 2011, except there was no error message displayed - which somewhat surprised me a lot.

Problem disappeared when I restarted engine but returned few miles later.

The helpfull man from Volvo reset the fault code and could not find any they car seemed to work ok again until a week later when it came back and I dropped it off at a dealer near my work. The replaced some kind of sensor (was it temperature?) and the car ran like clockwork again.

That exactly what happened: temperature sensor in DPF chamber that got replaced.

Anyway, the problem has returned. The engine has gone back to some kind of fail safe mode and have less power than a 1.6 litre engine...

I will go back to Volvo next week to find out what they say. Please share your findings if you have any updates as I am very interested!!!!!

I had no trace of problems later, however seeing this thread would be very much interested in knowing how you get it resolved so please keep us updated.

[tt82]

Well, when the we finally get some decent sunshine I intend on taking my EGR valve out and giving it a good clean. Hopefully I will be able to produce a guide for other members.

[N11BOT]

Originally Posted by SonyVaio

I get the feeling your problem lies with your DPF and the pressure sensors.

The running lumpy along with the drop in MPG sound like they go hand in hand and will most likely be because the car is undergoing a 'Regen Cycle' for cleaning out the DPF, the DPF uses excess fuelling to achieve this. On the exhaust strokes of the engine it injects fuel and thus uses more fuel and MPG drops.

If the pressure sensors are faulty it will be causing excess regen cycles as the car thinks the DPF is blocked and requires cleaning.

You would do well to have the car error codes read properly by VIDA/DICE (great if the indy has this but if not seek Volvo assistance or from a member with VIDA/DICE) once codes are known it should point in the right direction.

All in all I believe your problem to be either blocked DPF or pressure sensor problem causing excess regen cycles.

This ring true m'thinks

[cloggers]

Update: Volvo Assistance came out earlier today and the found fault code P042800 - CAT temp sensor signal to high.

Heading to the dealer tomorrow as they want to establish themselves if it is the same part as last time.

[cloggers]

Originally Posted by cloggers

Update: Volvo Assistance came out earlier today and the found fault code P042800 - CAT temp sensor signal to high.

Heading to the dealer tomorrow as they want to establish themselves if it is the same part as last time.

Update: The car has been to the dealer and they replaces the diesel particulate filter temperature sensor.

Apparently there is no link between the DPF temp sensor and the TMAP sensor replaced December last year. I hope they are right...

[PetterKB]

I have the same issue now, also with a 175ps 2.4d, and my local work shop told me the EGR-valve had to be replaced. Not trusting their judgement entirely, I also had a hydrogen carbon engine cleaning performed which debunked the EGR-valve theory and instead proposed that there is a faulty exhaust temperature sensor.
Error code is P208464 (signal plausibility failure), but I'm not able to find any link between this code and power loss . Anyone here who can provide some insight and enlightenment?