PCV valve? (and looks like you have found a fault?)

Just found this video talking about same engine in a Freelander.

https://www.youtube.com/watch?v=Wu2ndq5IGVI

The PCV appears to be part of this whole rocker cover unit that they dismantle at end of video. They talk about these engines needing them replacing religiously around 100k (mine is 96k).

Assuming the logic that this unit feeds air back to the inlet manifold and if blocked then creating back pressure that is venting through what maybe is a safety valve?

Will have a go changing this next although quite scary as tinkering with timing and ensuring not affected is clearly important!

 

This is from the VW manual on common rail:

If the valve is stuck open too much crankcase gas or air being drawn in will flow and upset the fuelling due to not being measured by the MAF or the leak is allowing excess air, something else causing it?

Can it be checked and cleaned to stop the leak, is there a crack etc. or would you prefer to change it (and is that really the identical engine in the video)?

Thanks Shearers 

I was able to prise off top of PCV and remove diaphragm and spring. There was nothing obviously damaged as far as I can tell. I cleaned them up and replaced but no different.

I saw smoke (after smoke test) coming out of what looked to be a valve of sorts upstream of the PCV and at the end where the crankcase gas comes up so I was thinking that these are not passing to the PCV but releasing via this other valve on the basis that either this valve has failed or that the route to the PCV is blocked?

The fact that the guy said the Land Rover specialists always changed this at c100K (some say 50K) suggests to me a limited life item and that in line with me seeing smoke appearing from it on a smoke test makes me marginally more confident of this fix than others however wont hold my breath...

99.9% sure that this same PSA KWNA engine is in Freelander and Evoque as well as PSA cars of course. Also looks identical on the video.

Cheers 

 

 

 

Looking online at the replacements the rear of the valve cover (that contains the PCV) you can see that the kind of valve that the smoke is appearing from is in the section that covers the timing chain (although one assumes all three gasketed areas are connected above so maybe doesnt matter!? 

So going ahead with that part change is what you are going to do?
Hope it sorts the problem!

Yes - rightly or wrongly!

Have dismantled and removed and new one arriving tomorrow...

My, potentially flawed logic is...smoke test showed smoke coming out of the small valve shown on diagram at opposite end of CCV.  

So seeing how I think these work it seems that the CCV should only open when at higher revs by pressure that has built in crankcase??

So if smoke directly appearing out of valve cover the other side of CCV then surely the CCV valve is open when engine not on. Which maybe suggests a failed CCV?

I genuinely am probably reverse engineering logic onto the problem in hope more than logic but will see over next few days when I swap this one. Again, at worst it needs doing at 100k anyway....but hopefully fixes the issue...

 

Changed PCV and tested - no difference

Changed out injector - no difference

One thing I did notice when removing injector that I originally did seal on was that it was wet with fuel up to half way up the injector. (It was wet because I'd been out on a run to test after PCV change.). Surely fuel should never go beyond the copper seal?

Now the leak wasnt enough to be forced out on top of engine and visible but seems its leaking past the seal.

At the very start I read a bit about cutting the seat where the seal meets the block to ensure a good fit.

I was thinking if that the seal between the two is poor then I wondered if it is still leaking.

It would fit with an issue right from the start.

Other thing I thought is to swap every injector and test (although all have been bench tested over time)

Only other thought is then a Ford Dealer

MOT is due on Saturday...

***** hell!

 

 

Image of injector below

This was reconditioned last year when installed so probably 150 miles done since then. 

Assuming blackened end shows bad fuel air mix / burn issues (one assumes could be due to other upstream issue) but i was concerned to see fuel half way up the injector after a quick test run out (c2 miles)

When I did replace injector I scraped around in seat before refitting and wonder if I damaged the seat therefore leak therefore problem?

Any thoughts appreciated

 

Sorry those changes didn't fix it (but I'm losing track of the issues that are left?)
Is there any crankcase leakage shown now after changing the PCV valve/cover etc?
Nothing should get past the copper seal but I don't understand why there is "pure fuel" there unless it's misfiring and fuel droplets are getting past.
Yes, maybe the seats should have been re-cut:
https://www.ebay.co.uk/itm/394338166238
Sorry, more potential expense if it is proven that there is a leak (presumably the tightening was done to spec - which I can probably find?)

So, what is the remaining fault/faults, are codes cleared and what returns, any changes to the PIDs you set up, why would the fault make an MOT fail?
I share your pain!

Have reseated all injectors and no better. all injectors were very wet up to about half way? And had blacked tips. 

also removed and cleaned intercooler.

When doing another smoke leak test I couldn’t get more than 5psi, but then couldn’t see smoke escaping either? Am going to have another go shortly. 

I half wondered about fuel valve on rail being faulty but sensor on rail shows sensible pressures I think at up to 150000kpa? Just had idea that too much fuel being delivered, but probably not enough pressurised air like tizer suggested - just can’t seem to find a leak.

If the demanded and actual rail pressures are close then i don't think there's a fuel delivery problem, at least to the rail.
Also (although I'm running out of ideas) AFAIK there is only a pressure sensor on the rail (although I'm willing to be convinced otherwise)

If the original problem (the choking/inability to run above 2000 rev/min) is still there then my next point would be to find out what is happening at that point i.e. what parameter is sticking/preventing an increase  - is this when stationary (i.e. can you investigate it whilst the car isn't moving) or is it under load (sorry if questions are repetitive etc as I'm losing the plot!)

If choking there's either not enough air or not enough fuel or being delivered at the wrong time or can't get rid of exhaust (less likely if it's otherwise sound)?

Is the throttle working correctly, have the parameters been reset, what about turbo parameters etc?
You can tell I'm looking for straws to clutch at!
 

Thanks Shearers

Really appreciate the note! I lost the plot a long time ago on this!

So still getting choking at c2500rpm - if i come off gas it seems to gather itself again at lower revs.

Feels very much like choking although under no illusions that this could / is likely to be lack of air (but cannot see anything via smoke test..) 

So all injectors were covered in fuel (assuming fuel not oil?!) when I reseated. 

So the fuel rail has a sensor at one end and a valve at the other that modulates fuel delivery and pushes excess back to filter and tank. Allows high pressure fuel pump to work all out but then it measures out what goes to rail.

Your point about desired vs actual fuel pressure makes perfect sense so guessing its all working fine, however have bought £25 second hand rail with both sensor and valve to test if any change and satisfy my curiosity about this part of it - This is away from logic and working purely on how it feels as an issue when driving car...ie flooding. 

Trying to get an MOT today..

Cheers again for thoughts and will test for Forscan heavily again as you suggest.

 

 

So changed the Fuel Rail and no difference. Still choking at 2500rpm. 

Failed MOT on steering rack boot but fixed and now have MOT which is a small positive!

Running diagnostics again and noticed that power to ECU is not consistent. Every 10 or 20 seconds the power drops to c6v. Wondered if this power drop interrupted commands going to engine for split second that at low load is not noticed but is at high load? See picture from Forscan. Blue line is Main ECU Voltage

That said more likely maybe to be turbo, although for same issue to arise in same way both originally and then after turbo had been sent away for reconditioning, that simply doesnt make sense.

I did have car open to elements (scuttle was removed) so engine got wet accidentally in early days (this time last year) so electronic quirk not impossible.

Booked it in with good auto electrician week on Thursday....however tried testing myself in meantime although no idea what I am doing on electronics (only ended up testing some grounds for continuity and removing, cleaning and replacing).

Any suggestions much appreciated.

 

 

Had expert diagnostic guy look at car yesterday. 

He acknowledged the issue is a very odd one and was surprised that the breadth of parts replacements hadnt fixed by pure chance!

Suggested that it is a fuelling issue in that the rattling sound shortly before the engine loses power was overfuelling. To isolate each injector he blocked each ones fuel feed from rail one by one and ran on three cylinders but we still got same issue.

He was surprised that no other faults were displayed (bar the basic Underboost) to give leads as to issue so was concerned that some previous hard code programming was hiding this. So next step to do a more costly full dealer level software reset to ensure this not happening and also using tool this will give higher level analytics for review....

Hi Luke,

Thank you very much for starting this topic – it really helped me solve a choking issue at around 2000 rpm during longer acceleration. I had a very similar experience with my S-Max.

I replaced two injectors and unfortunately broke the cap end of the fuel return pipe. I bought the cheapest replacement part available in the shop. After installing it, the engine started choking again, but without any error codes. I also changed the fuel filter and turbocharger, but I still couldn’t find the root cause.

After reading your post, I decided to try the old, broken return pipe again. Although it was leaking fuel, the engine regained full power. So I bought a brand-new fuel return pipe, and the choking issue disappeared.

It turns out the cheap return pipe couldn’t handle the higher fuel volume at 2500 rpm. This caused one or more injectors to become blocked, preventing them from opening and injecting fuel properly. The engine was running on only two or three cylinders until the excess fuel managed to pass through the restricted pipe. That’s why it ran fine at idle or low speed.

Since there’s no pressure sensor on the return lines, this issue doesn’t show up in FORScan. If you're experiencing similar symptoms, try replacing the fuel return pipe and let me know if it helps.

1 hour ago, mkratky said:

Since there’s no pressure sensor on the return lines, this issue doesn’t show up in FORScan. If you're experiencing similar symptoms, try replacing the fuel return pipe and let me know if it helps.

If you are saying that the fuel return pipes can't cope with the flow, a leak off test would seem to me to be needed.
This would show if any of the injectors have excessive leakage?

On 8/6/2025 at 11:38 PM, Shearers said:

If you are saying that the fuel return pipes can't cope with the flow, a leak off test would seem to me to be needed.
This would show if any of the injectors have excessive leakage?

The injectors should be fine. I had them tested at a Bosch diesel service before. Two of them showed high leakage, so I replaced them with Bosch reconditioned parts.

The choking issues started about a week later, immediately after I replaced the fuel return pipes – and they stopped right away once I installed a brand-new fuel return pipe.

11 hours ago, mkratky said:

The choking issues started about a week later, immediately after I replaced the fuel return pipes – and they stopped right away once I installed a brand-new fuel return pipe.

So, as the injectors were replaced due to excessive leakage and the problem was caused by a blocked return line, as above?
Were you able to find the source of that (tempting to just breathe a sigh of relief of course) AND could you share the source, cost and process for reconditioned injectors rather than going new or 2nd hand and the return line please? Thanks.

On 8/24/2025 at 10:23 AM, Shearers said:

  Thanks.

At first, I had the injectors tested because of frequent DPF regenerations, not because of leakage. I replaced two faulty injectors, but it didn’t help – the regeneration frequency stayed the same. Later, the original fuel return pipe started leaking because I accidentally broke it during assembly. The engine was still running at full power. When I replaced the pipe with a low-cost part, the choking problem appeared.

Here’s a link to the spare parts store (unfortunately only in Czech):

• Reconditioned injector: approx. £200 (they require the old part back)

• Faulty/cheap fuel return pipe: approx. £32

• Good quality fuel return pipe: approx. £51

Hi mkratky

Wow! that is very interesting. Sorry I have not replied but been on holiday and the car is now with the diagnostic expert guy, so I'd taken my eye off this thread. 

The current guy is brilliant and adamant its fuel delivery (but not a particular injector as all have been blocked and tested). We'd done fuel filter, uplift and high pressure fuel pumps at previous places so he is waiting for another similar engine to test pressures in the chain at his garage to assess what good looks like and then look to replace again.

But with your experience I am definitely going to buy a new return pipe from Ford tomorrow even if a rip off (over £100) tomorrow and try that.

Thank you and fingers crossed.

Luke

 

 

So mkratky

It worked. After 15 months of the car off the road and probably £3k spent it worked! A cheap pipe was causing the problem all along. 

Thank you so much for letting me know about your experience because I still wasnt close to changing the pipe despite having mentioned it as a thought way back in this thread. Every expert, friend and garage I spoke to suggested it wasnt going to be related to this....but it was!!!

Delighted to get my car back (getting it today).

Thanks again for letting me know.

Shearers - Thanks so much to you also for your support over the months. You gave me lots of good advice and most importantly hope whilst I wrestled with the potential problems. I really really appreciate it. You have been brilliant. My only terrible, terrible confession is this....that I am a Sunderland supporter....my family were from Durham (i've never lived up there but visited hundreds of times) and I have supported them all my life! Am guessing via your location and tag that you're a Newcastle supporter. Am so sorry to keep this from you but you were being so helpful!! Good luck for the season and I look forward to the Derby match! Thanks again and keep well.

 

 

Really glad to hear you got it sorted and can enjoy the S-MAX again!
Whilst we live local to Newcastle my MBH is also a Sunderland fan (wot, with our name!) I am a non-fan but like to see our local teams do well (derby matches in the Premier League should be interesting!

Thanks to @mkratky for the surprising solution!

Ah! Great. Don't feel half as bad then! Thanks again for both your help.

Hi Luke,

It’s great to hear that your S-Max is running well again.

It really was an unbelievable cause. There’s a 10-bar non-return valve in the return pipe, and it’s a very important component for the piezo injector system.

Your post pointed me in the right direction to find the problem. Without this topic, both my S-Max and yours would have been out of service for good.

I wish you no more problems with your car.