Intermittent limp mode

[jasbha]

Hi, newby hear trying to get some help with regard to an intermittent limp mode issue.

The cars a V70 D5 2004 with 171,000 miles on it. Probably worth under £2k so I don't want to throw too much money at it.

It happened under hard acceleration onto a main road, thereafter it went into limp mode whenever I accelerated hard. If I turned the engine off and re-start it was fine until accelerating hard again. I took it to my local garage and they diagnosed a sensor mounted on the radiator casing (is this the mass air sensor?). With that replaced they test drove it and found that the fault still occurred and advised me that the turbo needed replacement.

I took the car to a Volvo garage who said it was unlikely to be the turbo and thought it likely to be coking up of air intake downstream of the exhaust gas recycle connection, with this restricting flow. They said the delta between the flow calculated set point and the actual flow recorded would put the engine into a limp mode to protect it. Cost estimate for a decoke was £450 with risk that if the injectors were seized in then they would be £250 each to replace.

I now notice that after the sensor replacement the problem doesn't occur when the car is warmed up; no matter how hard I accelerate it performs fine. However, when not fully warmed up I can get the problem to occur; the computer message is engine service required.

Does anyone have any similar experience and is there a product that can clean out the air intake system without dismantling (if that is the likely problem). Any help would be really appreciated

[Harvey]

Front or rear engine mounts leaking /split letting in air ?.

[jasbha]

Front or rear engine mounts leaking /split letting in air ?.

Thanks for the response - do you think that's more likely than the decoke diagnosis I had? They did mention that the engine mounts were connected to the vacuum system and that this could also be a cause; I don't understand how that could be affected by the car being warmed up though. Any thoughts?

[M-R-P]

The price of the egr clean is a joke, you can do it yourself in an hour or two and that might sort it.

As Harv said, it might be an engine mount but I think they would've spotted that when you had it checked.

If the turbo had gone you'd be seeing loads of smoke,hearing loads of noise and it would be constantly slow.

Where abouts are you? Maybe someone local to you can have a look, we're pretty friendly like that

[jasbha]

The price of the egr clean is a joke, you can do it yourself in an hour or two and that might sort it.

As Harv said, it might be an engine mount but I think they would've spotted that when you had it checked.

If the turbo had gone you'd be seeing loads of smoke,hearing loads of noise and it would be constantly slow.

Where abouts are you? Maybe someone local to you can have a look, we're pretty friendly like that

Thanks for the offer - I'm near Kingston on Thames so quite a way from you unfortunately. I think the quote was for cleaning the top end of the engine rather than just the egr valve. I've cleaned out the easy to get to hoses leading up to the inlet manifold but haven't got to the egr. Is the egr visible after removing the mixing pipe or is it a little more involved than that?

Also, do you think that a clogged egr would lead to the limp mode issue when cold but not when hot?

[M-R-P]

The egr is sort of part of the mixer pipe. I've cleaned a few.

Another possibility is the fuel filter, an old filter can cause a fault.

[850 T5s]

hi there, did they read the diagnostic trouble codes when it was in the garage, if so what were they ? but as Harvey said check the front and rear engine mounts/vac lines 1st as it could be a leaking engine mounting

[jasbha]

Many thanks for your help and advice. The fuel filter is fairly new (circa 20,000 miles old) so would have thought that's still OK. I can't recall the codes that were read off although the mechanic thought it either the engine mount vacuums or restricted air path through inlet manifold if that helps.

I'm going to remove the mixer pipe and clean out all that I can get to and see if that improve things. I've also added a fuel additive to see if that helps at all. Is there any particular way of checking the engine mounts for leaks or is it just a visual inspection to see if there are any holes?

Thanks again for your help.

[850 T5s]

try disconnecting the vac lines off the engine mountings and blanking them off with a small bolt or similar then take your car for a drive to see if the fault occurs again if it doesn't you then know one of the mountings is knackered

[jasbha]

try disconnecting the vac lines off the engine mountings and blanking them off with a small bolt or similar then take your car for a drive to see if the fault occurs again if it doesn't you then know one of the mountings is knackered

Thanks - sounds like a good plan. I'll give that a go and see how I get on.

[850 T5s]

also check the intercooler aswell as these leak on the D5s and cause the same problems

[M-R-P]

Process of elimination, start with the easy stuff first. Egr cleaning, engine mounts (check all the hoses for cracks etc) blocked inlet...

You'll get there. These are great cars and all the effort is worthwhile in the end, I can vouch for that personally.

[850 T5s]

M-R-P is dead right start with easy stuff first

[jasbha]

Thanks all - I'll have a go with it over the weekend and will let you know how I get on.

Thanks again for the good advice

[M-R-P]

Let us know how you get on mate

[jasbha]

Had a go at cleaning out the egr line - cleaned out the mixer pipe and what I could see of the cooling manifold but didn't get round to accessing the valve itself as I noticed the upper engine mount/restraint was broken, and it looked like i'd need to remove and replace this to get proper access to the valve. Have ordered a replacement and will complete when received. I wonder whether this has put strain on the other mounts, which may be the culprit - it may have been broken for some time. I'll blank of the vacuum lines and test as suggested.

With regard to the intercooler, how do you test or inspect to see whether its blown or not?

[M-R-P]

The round top mount is a regular failure, they were replaced by square ones after a while. A visual inspection of the intercooler is often enough, look for wet spots or "ballooning".

[Plodmonkey]

Blank the egr off puts a fault code up but stops it from causing problems and ups your mpg a little. MRP is right about the intercoolers mine is doing the same at the moment did it first two weeks ago and doesn't hold full boost.

[jasbha]

Hi, I've just had another go at checking over the car, testing the engine mounts and trying to clean out the egr valve. The intercooler seems to be bulging at the bottom, very markedly so as it protrudes below the rad and a/c condenser in the middle but is flush at the ends. There was also a fair amount of oil on the protective tray that sites beneath the rad.

I'm looking at replacement intercoolers and there's on on ebay for £79 with a ThermoSwitch hole. Does anyone know whether to thermoswitch is a standard fitting? I can't find any reference to such a thing in the Haynes manual. The ebay sales do one without the thermoswitch too it seems.

Eurocarparts has one for just under £135 with no mention of thermoswitch sensor holes.

Can anyone advise? Would appreciate any feedback on where best to buy a replacement from too.

[T5RatherAmusin]

common as muck for the d5 for their intercooler to balloon
the d5s all had the bps outlet mounted on the cooler
its was a 2003+ roughly introduced they switched to having it on the outlet of the cooler