So took the car out on its biggest run since having the replacement engine and gearbox fitted.

It threw the following error on Foscan

Meant to add, it lost a lot of power at the same time as a “Service Engine Now” came up on dash.

Take it back to the garage.

Vac pump one way valve is the usual culprit but could also be a loose boost hose or a faulty turbo actuator.  Hopefully covered under warranty or at least sone goodwill towards the repair.

Thanks for replying Tom. Turbo spanking new so i’ll go on the other 2 first

Is the 1 way valve attached to the solenoid or the pump itself?

11 hours ago, madcourier said:

Is the 1 way valve attached to the solenoid or the pump itself?

It's on the vac pump.  Can't buy new ones from Ford without buying the whole pump (£500) so have to try your luck with cheap ebay versions.  Some are alright, others aren't, no way of knowing which you'll get.

 

Removed the old 1-way valve to discover it had fallen apart and there were 2 pieces of it left behind in the vacuum pump body, so hopefully ive nailed it.

Thanks for the help Tom

Well bugger me. Took the car along the bypass and it threw the code again. ***** off. I really thought id got it when i found that 1-way valve in 3 pieces…

Guess that leaves a boost hose but surely id hear that thing blowing? Also if its a pipe why does it not throw that code when im driving through town? Even if im booting it.

Opening a bottle of wine. Fck it………

18 hours ago, madcourier said:

Well bugger me. Took the car along the bypass and it threw the code again. ***** off. I really thought id got it when i found that 1-way valve in 3 pieces…

Guess that leaves a boost hose but surely id hear that thing blowing? Also if its a pipe why does it not throw that code when im driving through town? Even if im booting it.

Opening a bottle of wine. Fck it………

Worth checking the valve again in case it's already broken.  (Some of these really are terrible quality!)  May also be the vac pump itself, so it's worth checking that using a manual vacuum gauge before trying to chase hose leaks.

The PCM allows a certain amount of both underboost and overboost as a buffer otherwise it would be triggering codes regularly.  Something like 5 seconds worth.  So it needs a prolonged, high load, acceleration to be triggered.  My chosen test was always a dual carriageway slip road.

Good shout. I’ll arrange for a vacuum test of the pump itself. I did check the new valve for just that reason but its still in 1 piece.

Is this something i can do myself, or is the cost of buying the stuff i need for 1 use prohibitive?

Is there a guide on how to do it? I only seem to find videos on how to replace the whole vacuum pump.

Having a further think about this….

When the original engine went boom in a big way (3” hole in block) due to wetbelt failure, is it likely the vacuum pump itself is lunched?

11 minutes ago, madcourier said:

likely the vacuum pump itself is lunched?

Very probably.

On 8/18/2025 at 4:23 PM, madcourier said:

Is this something i can do myself, or is the cost of buying the stuff i need for 1 use prohibitive?

Is there a guide on how to do it? I only seem to find videos on how to replace the whole vacuum pump.

You can buy vac testers quite cheaply, sub £30.  But it is a waste for one use especially if you don't have much storage space.  I would expect any normal independent garage to have one you could borrow for 5 minutes.

But as above, if the engine was damaged by lack of lubrication then the vac pump probably was as well.  They often need to be replaced after wetbelt failure.

New vac pump ordered.

Manufactured by Pierburg. Apparently owned by Rheinmetall Germany and supposed to be very good whilst being  half the price of Ford.

Could have gone the breaker route i guess but you can never be 100% confident of a 10 year old used part…

Im about ready to set fire to this thing.

New vacuum pump fitted. Test drive on bypass - throws an underboost code again.

Any chance the new turbo is faulty? Is there a boost sensor on these?

Very unlikely a brand new genuine turbo is faulty - unless it's just a cheap eBay special instead.  It is possible that the actuator rod hasn't been adjusted perfectly though.

There is a recirc valve on these that fails, triangular shape, but I would expect a brand new turbo to come with a new valve.

There is a pressure sensor to measure boost pressure if that's what you mean.  There isn't a sensor to measure actuator opening length on these as far as I remember.

Really need to do some proper testing before spending any more money though.

What i think i’ll do at this point is give it back to the guy that fitted the replacement engine for me. If it is a turbo issue either he hasnt adjusted actuator correctly or in the unlikely event its the turbo itself then it will be a warranty job.

Either way it needs to go back to him as he bought the turbo for it so any warranty work would need to be claimed by him anyway

Its such a weird one because ive just been buzzing round town getting stuff for sunday lunch and she drives sweet as a nut.

Even when wot away from junctions etc.

It just seems to get shirty when im on dual carriageway/motorway

WOT from junctions around town barely creates any load.  That's just a quick burst of boost before you have to change gear.  Motorways are prolonged load/boost.

Heard from Pumaspeed and they reckon it may be boost solenoid or remnants of old wetbelt within the vacuum hoses..

Suggested i remove vac hoses and blow through with air line.

I will suggest these things to the garage

On 8/30/2025 at 4:14 PM, madcourier said:

Im about ready to set fire to this thing.

 

it'll probably manage this on its own... its a ford thing - its a great way to sell more cars

if this is a wet belt engine did you buy a secondhand engine ?  if so likely the same issue coming round again - if so a belt to go with the new pump and the new turbo would be a good idea

 

 

Not entirely sure how wetbelt fragments from the oil could end up blocking the vac pipes.  That seems like strange advice from Pumaspeed who I would generally trust and regard more highly than a Ford dealer.  

Boost solenoid is easy to reach & change if you want to try that, especially if that was kept from your old engine.  Though hopefully it will be sorted under warranty.

Yes it was Pumaspeed that supplied my replacement engine.

11 hours ago, TomsFocus said:

Not entirely sure how wetbelt fragments from the oil could end up blocking the vac pipes.  That seems like strange advice from Pumaspeed who I would generally trust and regard more highly than a Ford dealer.  

 

I thought it was "always" the wet belt shedding that was blocking the brake VAC pump ?

Seen youtube video of one guy showing the sump off replacement of everything - and I seem to remember he specifically calls out the failing vac pump it the first sign of wetbelt degradation 

if I'm not following things correctly... maybe the engine breather starts to draw in fragments of belt into the inlet manifold and then it all goes wrong ?