I have a 2014 reg Titanium Sport (diesel) which I have owned from almost new (bought with 5k miles on clock in 2014) and it has been trouble-free. 

Just recently, on a couple of occasions, it took 2-3 seconds to start. Aside from this it was running fine.

When getting a DPF clean, the car again took 2-3 seconds to start and the mechanic said he felt it surge a bit when he was accelerating. He suggested replacing the fuel filter as a precaution. After replacing the fuel filter the car did not start at all. Spent over an hour, bleeding & cranking, put the old filter back - tried everything. 
 

After giving up, the car sat for a couple of hours, and when tried again, it started!

That is where things stand now - if it has been left for a while, it will start. If it has recently been running, it will not. When running, it runs fine - accelerates hard, no surging or hesitation at all.

 

Bosch garage have spent hours on it and unable to determine fault. Rail pressure looks good, no error codes. It’s a complete mystery.

 

Anyone seen anything like this before? Any suggestions / theories ?

 

Thanks

 

I have taken it to a Bosch garage - they spent a few hours and were unable to determine the cause.

Ford garage want to charge me £174 per hour to investigate 😮. 

If the Bosch garage can't determine a fault with their own common rail system, I'm not sure there's anything we can suggest that will be of much help.  

I suppose that could mean the problem is not in the fuel system but something electrical preventing the injectors firing for some reason.  Assuming the Bosch garage used a generic OBD reader, it would be worth getting Forscan to check for any Ford specific fault codes. 

You could also try bump starting it when warm to rule out the starter getting slow, but that does feel like a straw-clutching suggestion.

That Ford labour rate is horrific! 

4 minutes ago, TomsFocus said:

If the Bosch garage can't determine a fault with their own common rail system, I'm not sure there's anything we can suggest that will be of much help.  

I’m hoping there might be someone who has seen this problem before - or has some interesting insight. 
 

6 minutes ago, TomsFocus said:

I suppose that could mean the problem is not in the fuel system but something electrical preventing the injectors firing for some reason.  Assuming the Bosch garage used a generic OBD reader, it would be worth getting Forscan to check for any Ford specific fault codes. 

The Bosch garage mechanic was pretty experienced - late 50’s and he said he was stumped - never seen anything like it. His only suggestion was an ECU problem. He suggested taking it to Ford - as maybe they’d seen this before.🤷‍♂️

Something you said got my noggin joggin - Is it possible that a low battery voltage might prevent an injector from firing? (Not sure how that explains why it starts when cold - but it’s a thought)

The battery seems ok in terms of Ah capacity - it cranked for ages, before requiring a jumper when I couldn’t start it. But I have gotten some ‘battery low’ warnings.

14 minutes ago, TomsFocus said:

That Ford labour rate is horrific! 

It’s taking the *****. It’s what some law firms charge!

14 minutes ago, HaroldIII said:

Is it possible that a low battery voltage might prevent an injector from firing? (Not sure how that explains why it starts when cold - but it’s a thought)

The battery seems ok in terms of Ah capacity - it cranked for ages, before requiring a jumper when I couldn’t start it. But I have gotten some ‘battery low’ warnings.

No, I would expect an injector fault to be picked up by the Bosch garage anyway.  But there are some things that prevent the ECU from firing the injectors - immobiliser, engine speed, rail pressure, etc.

Hot cables have more electrical resistance, so that can be the difference between the starter motor getting enough current to spin the engine at ~250rpm or not.  If the bump start did work, then the thick battery cables would need to be tested (potentially frayed at the ends reducing their current capacity) or the stater motor windings could be getting tired and would require a new starter.

I really would recommend trying Forscan to check for any Ford codes before spending more money on this.

I don't personally believe it to be an ECU fault, but I am wrong occasionally.

Thanks for the advice. I’ve booked it in with Ford to do the minimum diagnostic - at their extortionate rate. 
 

I don’t believe it to be temperature related as it doesn’t have to run for more than 30 sec before it won’t start again. 
 

One piece of evidence that puts a hole below the waterline of my battery theory is that I can get the motor to start/run by spraying aerostart up the air intake - to high revs - but it will not catch. Stop spraying and it dies. 🤷‍♂️

You can use Forscan yourself at a fraction of the Ford dealership cost.

@unofix can provide links for suitable adapters.

39 minutes ago, TomsFocus said:

You can use Forscan yourself at a fraction of the Ford dealership cost.

@unofix can provide links for suitable adapters.

I will check it out. 
 

I have a ThinkDiag. I can see if that adapter is compatible. 

39 minutes ago, HaroldIII said:

I have a ThinkDiag. I can see if that adapter is compatible. 

That would be a no 🙁

FORScan: https://forscan.org/download.html

vLinker FS cable: https://www.amazon.co.uk/JUTA-VLINKER-FS-Adapter-Diagnostic/dp/B0BB5SDNZ2/ref=sr_1_4?crid=3BZDCTFY8RXUR&keywords=vlinker+fs&qid=1696616312&s=automotive&sprefix=%2Cautomotive%2C150&sr=1-4

14 hours ago, unofix said:

That would be a no 🙁

FORScan: https://forscan.org/download.html

vLinker FS cable: https://www.amazon.co.uk/JUTA-VLINKER-FS-Adapter-Diagnostic/dp/B0BB5SDNZ2/ref=sr_1_4?crid=3BZDCTFY8RXUR&keywords=vlinker+fs&qid=1696616312&s=automotive&sprefix=%2Cautomotive%2C150&sr=1-4

Many thanks for the info.
Not being familiar with forscan, any disadvantage using iPhone vs laptop?

Using an iPhone or an Android phone means that you can not do any programming. You will be able to read all DTC's and reset service indicators and clear error codes. 

You will need a vLinker FD+ dongle for use with the iPhone.

https://www.amazon.co.uk/Vgate-Bluetooth-vLinker-Scanner-Diagnostic/dp/B08H8JHWP2

On 10/7/2023 at 10:31 AM, unofix said:

Using an iPhone or an Android phone means that you can not do any programming. You will be able to read all DTC's and reset service indicators and clear error codes. 

You will need a vLinker FD+ dongle for use with the iPhone.

https://www.amazon.co.uk/Vgate-Bluetooth-vLinker-Scanner-Diagnostic/dp/B08H8JHWP2

Thanks.

Started first crank (because it had been sitting for a couple of days), ran engine for less than 1 minute. Won’t start again. 
 

With Forscan (if I am reading the app correctly), looks like there is no fuel rail pressure…. (While cranking)
 

Desired pressure (FRP DSD) is high

Actual pressure (FRP) is very low.

Have you done a global scan for any fault codes first?

Not all of the PID's work on every car.  It's possible that you haven't chosen the correct rail pressure PID.  I'm not sure which work on this engine so it may be some trial and error.

On 10/10/2023 at 2:57 PM, TomsFocus said:

Have you done a global scan for any fault codes first?

There are a couple of fault codes but they are unrelated - an issue with the switch for cruise control and an issue with the passenger folding mirror. There also appears to be an intermittent one with the EGR valve.

 

On 10/10/2023 at 2:57 PM, TomsFocus said:

Not all of the PID's work on every car.  It's possible that you haven't chosen the correct rail pressure PID.  I'm not sure which work on this engine so it may be some trial and error.

There are only 2 things available to monitor regarding rail pressure - desired rail pressure and actual. I will graph a successful start - that should highlight whether the graph is showing reality. 

An update:

Managed to get some decent recordings. 
It appears that after running (even if only for a few seconds), it needs a good couple of hours before it will start again.

Successful start:

Revving the engine a bit:

Trying to start again:

 

It’s not clear to me WTF is going on…

18 minutes ago, HaroldIII said:

It’s not clear to me WTF is going on…

Me neither.  

The HP pump can't just stop creating all pressure.  It's a mechanical system so it will always provide 'some' by turning the engine over, even if it was leaking through something like a stuck injector.  So that makes it look more like an electronic fault - but I'm baffled by one that only occurs after the engine's been running and then disappears again later.

I'm fairly certain it won't be the rail sensor or even the wiring to it.  Fuel pressure regulator could be sticking - I'm not sure if there's a PID for that?  Otherwise I'd be considering an electronic fault inside the PCM.

On 10/17/2023 at 11:08 AM, TomsFocus said:

Otherwise I'd be considering an electronic fault inside the PCM.

Funnily enough, that was the remaining suspicion of the bosch mechanic, after all other avenues of investigation were exhausted 

So now is alright? fixed?

 

On 10/18/2023 at 12:03 PM, Bol said:

So now is alright? fixed?

 

No. It’s been with another bosch garage for a while. 
 

They think the EGR valve & DPF is the issue. 
DPF was cleaned, so I’m not sure about that. There have been intermittent faults reporting EGR valve stuck - but would that prevent it from starting?

I’m wondering if it’s not a battery issue. I had been getting “battery low” warnings on dash. It does seem to crank ok though so 🤷‍♂️

Ok, more data points….

Was driving the car to the garage today and when accelerating, it suddenly went into limp mode. There was a fuel rail under-pressure and over-pressure DTC. (I think it’s common they come in pairs - the over-pressure is a consequence of the sudden cut in power when limp mode kicks in). 
I think it also happened while the transmission was shifting gears, as there were some DTC’s from the transmission control module. Oddly the car actually cut out - which was a pain. Waited 3hrs & still didn’t start.

I replaced the battery by the side of the of the road - sadly that didn’t fix it.

However, I was able to start the car with a spray of cold-start  in fact, I am able to reliably start it with cold-start.

One other thing I noticed is that when I turn the car off, it doesn’t stop immediately - it seems to run for almost a second longer than it should - with a slightly odd note.

Any more thoughts  ? 

1 hour ago, HaroldIII said:

One other thing I noticed is that when I turn the car off, it doesn’t stop immediately - it seems to run for almost a second longer than it should - with a slightly odd note.

Any more thoughts  ? 

Has the fuel pressure regulator been replaced yet?  That's the usual cause of running on like this.

On 11/7/2023 at 7:43 PM, TomsFocus said:

Has the fuel pressure regulator been replaced yet?  That's the usual cause of running on like this.

No. I will look into that. 
 

On another score, I am told that replacing the EGR requires removing the engine - wtf?

31 minutes ago, HaroldIII said:

On another score, I am told that replacing the EGR requires removing the engine - wtf?

I don't have any experience with the S-Max.  On the Mondeo it's tight but just about manageable. 

There is an awkward bolt that needs to be removed by 'feel' iirc.

The S-Max bulkhead might be tighter, but even so, I reckon you'd get away with just top engine mount off so you could shift the engine forwards a bit.  Engine out seems excessive, but as I say no direct experience on these.

So, an update….

 

Mechanic was unable to replace EGR without removing engine - so we abandoned that. No other work was done. 
 

And, as mysteriously as this problem appeared, it seems to have disappeared. Car has been starting/running with no issue for the past couple of months!

The only thing that suggests it’s not totally normal is the delay when stopping the engine.  There is a good 2-3s from pressing the start/stop button to when the motor actually cuts out.