S40 (New) Engine 2.0D : Lacking Power Significantly

[imz]

Hello,

I hope someone can help me here.

My DPF on s40 2.0d (108k) was replaced about 13 months ago and little did I realise but it seems since then the car has had issues.

The main issue is there is a significant power loss, the car feels like it is just holding back but revs (takes some serious effort) over the 2800 mark so not in limp mode.

I have repeatedly checked fault codes over the months and nothing indicating power loss.

Throttle body seems ok, but what is the best way to diagnose faulty one?

EGR was changed for a new one so feel hopefully it can't be that and if it was would it not throw fault code?

Plenty of mechanics have looked at it but feel it is boosting fine so are ruling out boost leaks and turbo.

This has gone on for over 20k miles now so dont think it can be clutch etc.

Could be the torque that has vanished my but I am not too techy so not sure???

There is no fault code for DPF pressure sensor so I think that would be fine, otherwise I read it would be in limp mode???

Unplugged MAF yesterday and car started to kangeroo and was not driveable so I imagine that is not at fault - Plugged it back in.

Anybody have any ideas what could be causing the issue I have, the car holds back and will not rev up freely and softly like it should.

Any help is much appreciated, thank you in advance

[SonyVaio]

Although it has been checked a hundred times already it really really sounds like boost hose, vacuum pipe and or intercooler/pipe related. Basically I think you are either loosing boost or air somewhere.

The other possibility is the TCV.

[138gat]

I had a similar problem and changed the TCV for a new one from volvo, about £50 ish with vat
Problem not solved so swaped the TCV's round, top to bottom and vice-versa and got full power and boost back
Nozzles on new TCV's are slightly smaller and tapered so possibly not giving an air tight fit

[imz]

Originally Posted by 138gat

I had a similar problem and changed the TCV for a new one from volvo, about £50 ish with vat
Problem not solved so swaped the TCV's round, top to bottom and vice-versa and got full power and boost back
Nozzles on new TCV's are slightly smaller and tapered so possibly not giving an air tight fit

Hi thanks for response. I already tried this after probably reading your post elsewhere but unfortunately this did not work.

Thank you for your help much appreciated.

[imz]

Originally Posted by SonyVaio

Although it has been checked a hundred times already it really really sounds like boost hose, vacuum pipe and or intercooler/pipe related. Basically I think you are either loosing boost or air somewhere.

The other possibility is the TCV.

Hi Sony,

I think you're right and I have it booked it in to get it checked over again.

Is there any way I can test the TCV and also for boost leaks using VIDA, a little impatient to wait for garage to do their checks. If there is please can you tell me how.

Thanks.

[SonyVaio]

Unfortunately VIDA is of no help here unless there is a code stored pointing to a cause.

If you have a boost, vacuum or intercooler leak then it is good old fashioned hands on checking over all pipework and paying great attention to the folds and underneath of pipes as well as under jubilee clips. It is amazing how small a rip, tear or hole has to be to cause havoc. Some rips only show themselves when the pipes are flexed by some load going through them so to look at it may initially appear fine on a quick inspection.

TCV, you may well pick a 2nd hand one up cheap from a breakers or dismantlers. It is not a bad idea to have a spare one of these around. You can then change one then the other to see if any of them are faulty.

[imz]

Originally Posted by SonyVaio

Unfortunately VIDA is of no help here unless there is a code stored pointing to a cause.

TCV, you may well pick a 2nd hand one up cheap from a breakers or dismantlers. It is not a bad idea to have a spare one of these around. You can then change one then the other to see if any of them are faulty.

Hi Sony,

Thanks again. Does the TCV usually throw a fault code?

Thanks.

[gswede]

Check your exhaust manifold nuts.
Not sure if you have a CBV on that turbo assy but if you do, make sure to check the hose going to inlet plenum. On the petrol turbos (t5) it is notorious for coming loose, as it is not fastened. If loose, vacuum leak is the result and no fault codes thrown..
Lastly, how is the pcv checkvalve doing - further more, the pcv itself?

I drove around with a faulty pcv for years without it being noticed during service or otherwise, no code. It was all masked by a faulty checkvalve.

[imz]

Originally Posted by SonyVaio

Although it has been checked a hundred times already it really really sounds like boost hose, vacuum pipe and or intercooler/pipe related. Basically I think you are either loosing boost or air somewhere.

The other possibility is the TCV.

Hi Sony I had the car smoke tested today and there is absolutely no leak anywhere other than a little nozzle type thing on top of the throttle body from which smoke was escaping, is this normal?

The above was not from either of the two ports in which the vacuum pipes are attached.

There was air bubbles in the fuel lines and he suggested this may be the cause, of the power loss or possibly fuel starvation. Any thoughts on this?

Many thanks.

[SonyVaio]

What size bubbles are you talking about and how many? Is it a constant stream of big bubbles or just some little bubbles now and again?

Depending on when you last had the fuel filter changed then it may be worth a change. Just out of interest what fault codes have you been getting?

Does it actually feel like the car has gone into limp mode when it happens but just no light on the dash?