Diagnose my Mondeo

GravyMonster · 28 Jan 2013 at 13:08

The car in question is a 55 plate Mondeo 2.0 TDCI Ghia, 118k miles.

It started misfiring slightly the first Monday after we had the snow. Nothing major, just once or twice per trip, always around 2000RPM on low throttle. Some journeys it would be absolutely fine. I put it down to the cold weather and thought if it's still doing it when the cold snap passes I'll get her seen to. More fool me, but hey ho.

Around Thursday it started getting worse, misfiring every trip, still around 2000RPM, but with bigger judders and a cloud of soot appearing in the rear-view every time. I booked her in to be seen by my local indy on Monday morning (today).

Friday morning, she wouldn't start. Turns over fine, and all electrics work but won't fire, even when being jumped from the wife's Vectra so I'm pretty sure it's not battery related. A recovery truck has just picked her up and taken her to the garage to be checked over.

So what say you, mechanics of OcUK? I'm thinking fuel pump or the dreaded 'i' word. Either way I'm expecting to be raped in the wallet

iaind · 28 Jan 2013 at 13:15

Injector(s) probably, you'll only get raped if you dont do your research and take the first quote. Assuming it's just one, the bill should be about £200 (£100 for the injector, a few hours labour to test and fit)

GravyMonster · 28 Jan 2013 at 13:20

From reading online I thought it's advisable to get the whole set done at the same time? Is only repairing one like repairing one shock absorber?

iaind · 28 Jan 2013 at 13:23

Not really, it's your call. If its failed because of a defect in that particular injector then the others aren't necessarily going to die. If its just age and mileage then maybe, but personally I'd do one then see how it goes - if you have the same problem again soon then swap the other 3 but no point doing them all for the sake of it

Gibbo · 28 Jan 2013 at 13:56

Hi there

If it was a petrol I'd say coil packs, but doubt diesel even has such a thing, so that leaves injectors. Surely the Mondeo uses the older common rail injection? If so not crazy expensive like modern direct injection versions.

Brookert · 28 Jan 2013 at 14:13

Misses can be caused by air leaks too, so I wouldn't rule that out.

GeForce · 28 Jan 2013 at 14:18

Gibbo said:
If it was a petrol I'd say coil packs, but doubt diesel even has such a thing, so that leaves injectors. Surely the Mondeo uses the older common rail injection? If so not crazy expensive like modern direct injection versions.

I think this engine is the PSA DW10 based unit, which is indeed direct injection (PSA terminology is HDi). It does have glow plugs but they are typically not needed for starting, and are extinguished once the coolant temperature reaches a threshold value or the engine exceeds a certain rpm for a certain amount of time.

Edit: Ignore everything, it's not the PSA one. Sorry.

GravyMonster · 28 Jan 2013 at 14:33

Brookert said:
Misses can be caused by air leaks too, so I wouldn't rule that out.

Interesting, thanks. Any details on why this is?

GeForce said:
It does have glow plugs but they are typically not needed for starting.

I thought glow plugs were only used for starting? I ruled them out as they generally don't cause misfires as they only operate for 20-30 seconds when the car starts.

I suppose it's possible there's two separate issues here - glow plugs (not starting) and injectors (misfires).

blueboy2001 · 28 Jan 2013 at 14:38

Injectors rarely cause a non-start fault. The engine can run with a failed injector.

It could be the pump, but I'd be optimistic at this point and suggest a sensor - either fuel rail pressure, cam position sensor or crank position sensor. The latter 2 always cause the engine not to run if they fail because the injection system has nothing to time itself in relation to the engine position.

Before I read it wouldn't start though, I was thinking a split intake pipe. The one which runs from the intercooler to the bottom of the EGR valve is a common failure - it often split on the engine side where you can't see.

Just be careful with your choice of garage for this sort of fault. I wouldn't let anyone replace the injectors unless there was a report from a Delphi diesel specialist showing the test results for the injectors on their test rig. Likewise the pump. These are the only places that can test and refurbish these to the manufacturers spec.

GeForce · 28 Jan 2013 at 15:08

Spunkey said:
I thought glow plugs were only used for starting? I ruled them out as they generally don't cause misfires as they only operate for 20-30 seconds when the car starts.

I'm only familiar with the PSA HDi engines, but the plugs are only energised for starting if the ambient temperature is below a threshold. The ECU may energise them post starting to aid smooth running and emissions for the first few minutes if it deems it necessary.

This is in contrast to the older indirect injection (IDI) engines where the plugs were vital for starting (you had to wait for the coil light to go out on the dash before cranking, otherwise lots of white smoke!).

kidloco · 28 Jan 2013 at 15:15

Brookert said:
Misses can be caused by air leaks too, so I wouldn't rule that out.

Yep, my Mondeo tdci was recently spluttering at low revs, and smoking under acceleration. Turned out to be a split air hose.

GravyMonster · 28 Jan 2013 at 15:19

Would a split hose prevent the car starting?

Brookert · 28 Jan 2013 at 15:32

Spunkey said:
Would a split hose prevent the car starting?

Hard to say, not starting could be all sorts of things, like cam position sensors or Bad coolant sensors, loads of things. Battery good?

GravyMonster · 28 Jan 2013 at 15:34

Don't know for certain, but jumping it made no difference, so I assume so.

Dogbreath · 28 Jan 2013 at 15:55

Spunkey said:
Would a split hose prevent the car starting?

Not usualy, which is why BB said he only considered this before he read of the starting problem.

Third Opinion · 28 Jan 2013 at 16:55

Same as my old man's TDCi, definitely injectors. Such a common fault.

iaind · 28 Jan 2013 at 17:11

Thinking about it, if its not starting at all and just keeps cranking, it's more likely to be the crank position sensor - very common too.

Third Opinion · 28 Jan 2013 at 17:21

I know I will get flamed but when you look above at all the common problems, many expensive (not including DMF, DPF) I always wonder why Mondeo's are recommended so highly against other marques.

I know they have nice interiors and drive well but they can quite often become money pits. Saying that I don't dislike them.

Sorry not very appropriate in this thread maybe it is just an observation, just many spec new car threads end in Mondeo, Mondeo, Mondeo but there is another side.

Anyway ignore me as I drive a Fiat Diesel and an Alfa Romeo V6 so I should keep quiet lol.

iaind · 28 Jan 2013 at 17:28

The potential issues with a Mondeo TDCi are the same as those inherent in any other common rail diesel. You'll rarely see this generation of Mondeo reccomended around here in diesel form - if someone is looking at this sort of age and needs diesel its normally the VAG PD cars that are recommended as these are slightly more prone to the issues than others

I wouldnt exactly call them money pits though

Brookert · 28 Jan 2013 at 17:35

iaind said:
The potential issues with a Mondeo TDCi are the same as those inherent in any other common rail diesel. You'll rarely see this generation of Mondeo reccomended around here in diesel form - if someone is looking at this sort of age and needs diesel its normally the VAG PD cars that are recommended as these are slightly more prone to the issues than others

I wouldnt exactly call them money pits though

Yea, far from money pits. Just look at the sheer volume of dagga dagga mondeo's around.

If it's struggling to start, but runs fine when it does, I would also be inclined to suggest the crank position sensor.