Mondeo Mk4.5 2.2 TDCI Limp Mode.

[Dave Holland]

Hello all,

Bit of a strange fault here, not something I've known from previous cars. Mondeo 2.2 TDCi 200.

First manifested when filling up with a different brand of diesel, within 2 miles car went in to limp mode (engine malfunction readout and beep but no EML), having otherwise been fine. Switched off and switched back on again, no faults for a further 450 miles, filled up with fuel again yesterday and drove a mile back home. This morning, less than a mile later engine malfunction flashes up again, and car now cuts out, and requires 4-5 seconds of cranking to restart. After restarting it would then drive fine but suddenly go in to limp mode (but keep running thankfully). It's now undriveable as whilst I can risk limp mode, I can't risk it cutting out at motorway speeds. 

I have read the codes and nothing is showing and no EML is illuminated.

I've heard about some Ford models (seems to be common amongst Kugas?) being fitted with very fine fuel filters which can clog and restrict fuel flow but surely this would not be sufficient to cause this issue? Although possible it seems very unlikely the issue is with the type of diesel being used and this is likely to be purely a coincidence? I will change the fuel filter as precaution but it was only changed around 1 year ago, prior to my ownership.

In the absence of any codes, can anybody recommend any next steps please?

Thanks

Dave

 

[pragmatix]

What are you using to read the codes, not all readers show all the codes.

[Dave Holland]

It's a fair point, a mate's just reiterated that too. Up to now I've been using one with basic OBD2 functionality, but I've got access to a Snap On one which I'll use tomorrow and hopefully be able to shed some further light on it. Thanks very much for the reply. 

[pragmatix]

A very good code reader is Forscan it's a free download,, down load from here http://www.forscan.org/,  you will also need a modified ELM connector I use these https://tunnelrat-electronics.fwscart.com/USB_Modified_ELM327/p4541936_17045457.aspx  You will need a laptop too😀

[Dave Holland]

So I've used a copy of Forscan (a neighbour with a Fiesta ST had one luckily) with a genuine lead, and there's absolutely nothing stored.

I've been using another car the last few days so haven't had it out for a spin yet. I'll be able to borrow his equipment again, is the next stage to have it plugged in during a run and see if any codes show up when the fault does?

Thanks

Dave

[Tdci-Peter]

7 minutes ago, Dave Holland said:

So I've used a copy of Forscan (a neighbour with a Fiesta ST had one luckily) with a genuine lead, and there's absolutely nothing stored.

I've been using another car the last few days so haven't had it out for a spin yet. I'll be able to borrow his equipment again, is the next stage to have it plugged in during a run and see if any codes show up when the fault does?

Yes, that sounds a good idea. Some codes do vanish very quickly, some linger for a long time. If any lights come on or messages, pull over and try to read the codes without turning off the ignition. If that fails (some operations like clearing codes can not be done with the engine running), stop the engine, put ignition on and repeat the scan immediately.

I assume Forscan did all its usual operations, and listed all the modules found, with no faults displayed for any. PCM, ABS, IC, probably steering and a few others, at least, should show.

With a bit more effort, Forscan can be set to log live data like fuel rail pressure, and would capture any unexpected dips. Though it can take a bit of interpreting to separate normal events from faults.

All common rail diesels will have fine fuel filters, the pump and injectors are extremely sensitive to dirt. It could be wax due to old stock of non-winter diesel, or dirt or organic growth due to water getting in to a filling station tank. So filter is worth doing.

[Dave Holland]

That's a very thorough answer Peter, thank you.

I've done the fuel filter this evening (turns out these are an absolute pig to get going again after swapping it out, have to clamp of the fuel lines properly next time!). Cut the old one open out of interest and the filter itself was good and black, with a load of discoloured fuel around it. However no thick gunge and no visible obstructions.

I've changed plenty of filters on other vehicles in the past but never thought to check inside them, so I'm not sure if this is indicative of a heavily contaminated filter. 

The fault often occurs at around 2000-2500 rpm on full throttle so an educated guess suggests very temporary fuel starvation? (Did originally think a boost issue/leak until the car actually cut out completely) If so, would fuel pressure dipping at the rail suggest HPFP rather than something along the lines of an injector fault? I'm assuming the lift pump would be working at a constant flow?

Thanks very much again, will hopefully get to the bottom of it over the weekend!

Dave 

[Tdci-Peter]

3 hours ago, Dave Holland said:

would fuel pressure dipping at the rail suggest HPFP rather than something along the lines of an injector fault? I'm assuming the lift pump would be working at a constant flow?

On my car the pressure in the common rail is very dynamic, it almost mimics the accelerator pedal. It seems that quite a lot of the control over the amount of fuel injected is provided by the diesel pump.

FRP is fuel rail pressure, APP is accelerator, MAP & RPM are what they say, VSS is vehicle speed, VCV is the valve in the diesel pump that controls the output flow. Time is in sec, the ms is an error, it always does that.

On that run, FRP varied from 27000kPa (270Bar) to 150000kPa (1500Bar). There was no (known!) fault on my car at the time, the run was just to see what was happening.

However, if the car was cruising at steady accelerator position, then an unexpected dip in FRP, especially if linked to an error, would indicate fuel starvation, or a problem with the VCV maybe. Forscan can display DTC count, so can show just when an error happened. I chose a dynamic section of the log for that picture, to show the variation.

The 2.2TDCI may be a bit different in detail, but I think all these common rail diesels use the same basic system.

Most Ford diesels have no tank pump, the main pump has to suck fuel up from the tank, and they do not work at all well if any air gets into the input side of the pump. So air ingress into the system is a possibility. They are all a pig to start, unless you prime the fuel system with a hand pump in some way.

If the details are of any interest: These pumps are two stage. The first stage delivers a flow rate pretty much proportional to rpm, at just a few Bar of pressure. The VCV then dumps a controlled amount of this fuel back to the tank, or to the filter. The remainder is forced into the high pressure stage, which is cam driven pistons, so the piston stroke is determined by the amount of fuel the first stage pushes in. This fuel is then delivered to the rail at the high pressure. So only the fuel actually needed by the injectors is pumped up to the massive pressure in the rail.

Major air boost problems, and most other sensor problems, tend to raise DTCs. It does seem that some fuel related problems can escape detection, though you did get a malfunction message, so there must have been an error code at some time. On my car, code P0299 (turbo underboost) does not light the EML, it does light the Engine systems warning lamp, and it does disappear after just a couple of ignition cycles. Also a basic OBD reader does not find it, but Forscan does.

 

 

[Dave Holland]

Interesting to see such a strong correlation between them, it would at least easily pinpoint any anomaly with fuel delivery. The logging of live data like this should help.

The car has only done 75k miles so I'm hoping the fuel pump isn't the culprit, although in a way, I'm hoping for a logged fault code because I can then at least look into that further. 

The detail regarding the pump itself is gratefully received, I was unaware there was no lift pump, it would explain why fuel flow could easily become severely restricted if the high pressure pump is having to draw it from the tank.

I have done around 60 miles today since the fuel filter change and it hasn't missed a beat, despite me thrashing it and trying to mimic the conditions that starved it before. On the day the issue occurred I couldn't drive more than 4-5 miles without an engine malfunction. 

I'm not 100% certain this has fixed the issue and the fresh filter could be temporarily masking an issue with another component. However for the moment it does appear to have solved it. 

I'll update again shortly, but thanks again for the excellent information.

Dave

 

[Tdci-Peter]

2 hours ago, Dave Holland said:

I was unaware there was no lift pump, it would explain why fuel flow could easily become severely restricted if the high pressure pump is having to draw it from the tank.

I can't say for 100% certain that the Mondy 2.2TDCI has no lift pump, but Ford do seem allergic to putting them in!

I have looked at a parts diagram site, and it describes the unit in the tank just as "sender assy", not sender and pump, for the 2008 - 2014 Mondeo 2.2: https://ford.7zap.com/en/car/39/no/31/1567/15712/68684/

It certainly sounds promising that the filter was the culprit. Hope so!

The time to do a live data run is when the car is working ok. Then you have a benchmark to compare with if anything does go wrong. That is one reason why I did one, as well as curiosity!

With Forscan, you can set up the parameters in advance (not too many, or the graph is a mess). Then maybe drive to where you can get the sort of run you want. Plug the adapter in, make sure the cable is safely run, and the computer is secure, press start to start acquiring, drive for anything up to about 45 mins (data gets a bit big and hard to navigate in if it is too long), stop, press stop on the computer, and then most important, save the data (Forscan does not do this automatically!). No need to even glance at the computer/device while driving.

It can also log cold starts, showing just how the rail pressure & rpm ramp up while cranking, then jump up and stabilise once running. That is another potentially useful benchmark to have.

 

[pragmatix]

With regards to the filter my brother has just bought a focus that kept cutting out, he changed the fuel filter and all is now ok, the filter can cause all sorts of fueling problems

[Gary11]

Hi. Sorry in invade on you post. But i have a 2009 mondeo 2.2 with same issue. I changed the maf sensor. But 20 mins of driving same issue limp mode. Seems to drive but no boost. So my next option by the sounds of things would be a service. Have the filters changed. This problem is a headache because i just got the car 6months ago lol. This must be a common fault cause my old 1.8 did this aswel. 

[unofix]

2 hours ago, Gary11 said:

Hi. Sorry in invade on you post.

feel free, invade away this thread has been dead for 4 years ! 🤣