First post so please be gentle....sorry if this is going over old ground but I've done a fair bit of homework and only the same few articles keep coming up. Just posting out of desperation really in case there's someone with a bit of deeper knowledge out there.
I just bought a Sept. 2010 Mondeo 2.0 TDCI 115 Zetec with 100K on the clock. Really nice car. On the way home the MIL comes on, and eventually goes into limp mode. Did a bit of research, bought an ELM-327 cable and downloaded Forscan. Codes showed that DPF was choked. Tried a static regenerate but it wouldn't let me (unspecified fail). Reset the soot levels to zero then kicked off the static regen (not sure you're supposed to do this but took relevant safety precautions) which worked. Was then able to clear all codes and car went fine for a day or so, but soot levels quickly built up again and same thing happened.
Oh well, I thought, not the end of the world, from all I'd read the DPF is only supposed to last 80k miles or so, so that's most likely the problem. Sourced a new one for £509 and the company that sold me the car contributed £200 towards that (the amount they reckoned they could get the existing one "cleaned" for) which I thought was pretty fair. Fitted the new unit cleared all the codes and re-set the values and the car went beautifully - definitely up on power than with the old DPF.
Too good to last though:- yesterday the engine malfunction 'information' light came on (not the actual MIL and no forced limited power). Code was P244C 'Catalyst temperature too low for DPF regeneration bank 1'. Even though the car has only done about 200 miles since I fitted the new DPF, the soot loading values were up over 100%. I cleared the code and today my wife said there was a burning smell when she got to work (good) and this evening one of the soot values was down to 87%, so it looked like it must be trying to regen. I took it for a run for about 20 mins keeping revs near 3000 but the soot level crept up and eventually P244C came up again.
I brought up the catalyst temperature senders on the live data, they were about 200 at idle. I found that I could get them to a higher temperature by giving plenty of throttle in 4th rather than just keeping revs high in 3rd, so the were over 300 sometimes but not easy to keep it that high for long (no motorway nearby). The soot levels went down a little at one stage but eventually seemed pretty stubborn at about 110%. I brought the car home and tried a static regen which seemed to be working for about 10 mins but then it ended saying it had been unsuccessful, and the P244C came back. I now also have P246B 'vehicle conditions incorrect for DPF regeneration' which I think means the soot levels are now too high. I could clear this by re-setting the soot levels but I didn't want to do this on the new DPF, and I've reached the limit of what I can find out by searching.
So... if you've read this far and have half a clue what I'm on about, maybe, just maybe, you might be able to answer these questions:
1) At what soot loading value should the system try to kick off a regen? And why are there 2 different values? I've read some places that once over 95% that's the end of the DPF, which is going to be really painful if true.
2) Are the temperature sensors prone to failure? On the live data they seem to be behaving normally; with this kind of sensor I'd expect it to either work or not, it would be strange to go out of range.
3) Could a sticking EGR valve be causing the problem? I understand it's supposed to close during regen, if it stays open the temperature may not be able to get high enough?
4) Is the differential pressure sensor likely to be faulty? And what value should I expect to see on it when driving? It sits at 1kpa when idling but does seem to go up to quite high numbers when driving. I see lots of them listed for sale which makes me think they might be a failure point? If it was reading high it would presumably push the soot values up too quickly?
Well, clutching at straws as you can see, and I'll be really grateful to anyone with a bit of knowledge. I'm really trying to avoid having to take it to a main dealer because apart from the distance involved that will totally ruin my mission to get the youngest car possible at the lowest price, where ex-lease Mondeos are unbeatable. I was vaguely aware of DPFs but if I'd realised all the problems with them I'd have bought a petrol one....
Thanks in advance.