Technical Croma DPF / Engine issue

[BrianMcL]

Hi There!
I'm looking for some help / advice on my 56 plate 1.9 8v JTD Eleganza please.

I've had it since I bought it new from the dealer in April 07 (pre reg 30/9/06 so warranty expired) and it's suffered a few faults which up until now have been fixed OK. It's been MoT'd and serviced by he same dealer since new.

However, in Jan 10 about 4k miles after the service it reported a DPF issue so back it went to the dealer. The changed the oil and filter and regenerated the DPF at a cost of £193.

In Feb, about 500 miles later, the check engine light came on so back it went and this time it was an ECU reflash, oil change and DPF regen which they said FIAT recommended but that they didn't think would work. Another £130 down.

It came on again last week (about 500 miles), so back it went and sure enough it's reporting a DPF issue but no-one believes that this is the cause.

They've opened a call with FIAT who say that they need to run though a checklist that will take 4 - 6 hours at a cot of £65 ph + VAT before they might know what the problem is.

I've called FIAT head office and they're going to look into it but don't know when they'll be able to tell me when they'll be able to tell me whether they'll be able to offer any goodwill.

It's beginning to feel almost as if the car is a write off (they reckon the value is about £4k) as who knows how much the problem will cost to fix once we know what it is.

I'd therefore be very grateful if anyone here could give me any advice or pointers about how best to approach this as I'm not sure I'm ready just to walk away from the car yet. It also seems like a terrible waste.

I've got ECUScan and a VAG com cable so could run diags OK but I wouldn't know what any of it meant.

If anyone here can think of anything I;d be very grateful.

Best regards,
Brian

 

[DoIDon'tI]

Hello, sorry to hear about the problems you're having. If you can post your ECUScan results on here (specifically, the code which has caused the light to come on) then that would be great. 500 miles sounds about right for a DPF regen cycle, sounds like it's having problems during the regen process. Out of interest, what happens if you try forcing the regen using ECUScan?

It might be something as simple as a faulty pressure sensor on the DPF, even if it's the DPF it's not the end of the works as the same part is used on the Vauxhall Vectra. Before you go any further though, you need to find out what's putting the light on. I understand it's frustrating when you don't know what's wrong with your car, but there are some very helpful people on here. I'm sure Keithglos, s130, arti_abarth, Doofer et al will be along in a few hours

HTH.

 

[BrianMcL]

Hi DoIDon'tI,
Thanks for replying so quickly.

The garage were possibly slightly less negative this evening and suggested that perhaps it just needs a really good blast to let it complete a regeneration cycle. Personally I'm not totally convinced because in limp mode it's not easy to get it to do much but who knows?

They didn't want to give me my car back tonight as they weren't sure whether the mechanic had put it back together (?) but they did say that the results were the same as before with the fault code showing a DPF fault, oil 97% used (they said the mechanic said that the oil was fine) and the filter showing normal clogging.

If I get it back tomorrow I'll run the ECUscan diags and post the results here.

Apart from the fault code what else would be important?

I can't help but feel that the sensor reporting oil 97% used can't be good and I'd imagine that there must be some kind of oil sensor problem.

Would you know whether an oil reading like this would cause the car to go into limp mode on its own?

Thanks again for the advice so far - already I'm a bit less depressed than I was this morning!

Best regards,
Brian

 

[DoIDon'tI]

I'm getting the impression that the garage doesn't know one end of the car from the other. If they haven't cleared the 'oil 97% used' indication (which is simply down to the number of regenerations carried out) at the same time as changing the oil then it doesn't bode well. ECUScan will allow you to reset this value if you're stuck anyway.

Sounds like once you have the code you'll have a way forward - the DPF codes are quite specific (Nick aka s130 knows a bit about these). The thing to remember is this - a clogged DPF is unlikely to put the engine check light on so 'a good blast down the road' will not clear the problem.

The way the car tells you that the oil is "used" is by flashing the oil pressure light and giving you a "Change engine oil" warning on the dashboard, it's all in the manual. What you are describing is the failure of a component in the DPF/Regen system, the fault code will help you determine which one.

I'll look forward to discovering what code it is - my fingers are crossed for one of the sensors as they're cheap compared to the DPF

 

[BrianMcL]

I've wondered about how much they know about the car on more than one ocassion myself:bang:

They've physically inspected and cleaned the filter at least twice now and said that it's OK both times - I don't think they'd have missed the chance to tell me to replace it if they weren't sure.

The first time I had the problem one of the service desk guys almost agreed with me that the cause of the initial DPF filter warning was most likely because they'd forgotten to reset the indicator. They've backed away from this quite some way now though and apparently it's most likely my driving style that's the problem.

One even went as far as to say that when I see the check engine light what that means is to give the engine some real welly as it's not getting the chance to complete the DPF regen cycle. Seems a strange warning though as I'm not sure how you would check the engine at 70mph in 4th or 5th on a motorway

Meanwhile back on Earth, am I correct in thinking that the oil reading is some kind of algorithm related to engine use, service history, DPF cycles, etc., rather than it actually testing the oil, or at least is more maths than chemistry?

Thanks again - I'm almost looking forward to getting it back and plugging in the ECUscan software and maybe getting to the bottom of an issue with it for once.

 

[Crombel]

The percentage in FiatECUScan is the condition of the oil, so 97% is very good and "next oil change" should be indicating about 40000 km.
If "Average distance last 5 regenerations" is about 1000 km your DFP should be OK.
The forced regeneration doesn't work in ECUscan yet.
The "oil replacement" actuator works and if it isn't reset you can get the DPF warning light.

 

[BrianMcL]

Well, got the car back from the dealer, still with the error and no further guidance on what to do next.

Took the plunge and plugged FiatECUscan in and got the following:
Fault P1206 - clean or replace particle filter
The narrative is
No help available at present
The reason for this fault is that the ECU has received very high signal from the sensor. The fault is not detected now, but is stored in memory. Clear fault codes, and observe for future appearance of the same fault. Dashboard warning light was activated for this fault.

I think the relevant settings from the diagnostics are:
Particle filter obstruction 79.41%
Avg last 5 regen cycles 304 Km (at least 2 of these have been forced by the dealer)
Last 5 regens avg duration 502 sec
next oil change 48500km
Oil deterioration indicator 97%

Not sure whether this is good or bad news but if the car's saying that changing the filter might be required and the dealer's had it out and cleaned it a couple of weeks ago then should they have been able to tell if it was damaged?

 

[Crombel]

I think it is good news.

Maybe you can clear the fault and hook ecuscan to your car from time to time.
The highest value of filter obstruction I have noted was 102 % and the lowest 21 %.
Only one time I have noticed that regeneration was taking place: at once fuel consumption was very high during 10 minutes. (av. reg duration 605 sec)

I have my car for four months/ 5000 km.
1.9 120hp 8v

 

[BrianMcL]

Hi Crombel,
Thanks for that.

I'll reset the code, take it for a drive and see what happens.

Fingers crossed!

 

[BrianMcL]

Cleared the fault code and took it for a drive.
I kept the speed at a steady 60mph in 5th with the revs as close to 2000 as I could keep them.

The diags have updated as follows:
Particle filter obstruction 15.03%
Avg distance last 5 regens 653Km
Avg duration last 5 regens 515 sec
Next oil change 48000km
Oil deterioration 96%

Seemed to lack a little low end power though but from my interpretation of the above whatever's wrong probably isn't a DPF issue.

Also, I wonder whether the garage misunderstood what oil deterioration meant when the told me that it was 97% deteriorated - I take it for a blast, get it to regenerate and now it's 96%. That would seem to suggest as you say, Crombel, that rather than a measure of deterioration it's a measure of how much it's got left. Hmmmmm.

DoIDon'tI - you might have been very right when you suggested that they don't know one end of the car from the other!

There's still something not right with it though so would things like air pressure, etc., be sensible things for me to look at next or is it still a bit too early for me to be too optimistic about the DPF?

 

[Crombel]

The "oil deterioration indicator" is an algorithm that calculates the condition of the oil that has to be reset with every oil change.
It affects the DPF regenerations lets hope that the problem with your car is only due to the fact that the reset has been forgotten.

Is the engine light out now?

The values are very good now all you can do is waiting if the DPF regeneration takes place after 1000 km or so without any alert.

 

[BrianMcL]

Hi Crombel,
The light went out OK and it's stayed out all day today.

Fingers crossed that whatever's wrong is nothing major and maybe all that's needed is a slightly more agressive driving style every once in a while. I'll keep running the diags on it every couple of days and if anything odd happens I'll post here again.

It really is scary that the dealer didn't know what the oil degredation indicator meant but now that I do I'm a lot less bothered about that part.

I'll also post again with how I get on with Fiat's customer care.

Thanks again to both you and DoIDon'tI for your guidance and support - you've both saved me a lot of time and worry over the weekend. :worship:

 

[Caravadossi]

The percentage in FiatECUScan is the condition of the oil, so 97% is very good ...

Thanks for the interpretation on the oil degrade reading. I’ve just done some 350 miles with a faulty EGR valve before it was replaced - & was concerned about any domino effect. My oil degrade reading was 92%, & when I queried that with the Sooty the interpretation was this was a negative – when in contrast, it is a positive reading. The 92% reading must be calculated from the 36k mls service – as the oil & filter were changed at 45k mls, with no re-sets. I’ve some 7k mls remaining before reaching the 54k mls service.

----------
55 Croma II 1.9/16v 150hp

 

[BrianMcL]

Well, I've kept going with the Croma through various cycles and it's become fairly predictable.

Just after a regen it runs fine for a while - actually very pleasant to drive - and then gradually the performance starts to degrade to the point where even a slight motorway gradient needs to be tackled in fifth and then fourth and eventually the check engine light comes back on.

I then take it for a good, steady drive, make it regenerate and then it's fine again.

I've got a feeling that whatever it is might not be all that much but I'm open to suggestions.

I've changed the air filter today and had a look at the pipes around it and the all feel OK.

Don't know if this makes any sense to anyone but it just feels that it gradually gets suffocated, clears itself and then starts again.

If anyone's got any ideas about what to check, or even what to look out for in ECUscan I'd be very grateful.

 

[BrianMcL]

At 42989 miles my readings per ECUscan 1.6 and 2 are
Particle filter 68.41%
Avg distance of last 5 regens 1050km
Avg duration of last 5 regens 553 seconds
next oil change 42000km
oil det 84%
Avg temp last 5 regens 628.16 deg C

Whatever's wrong with my engine I'm less and less convinced that it's a DPF issue.

Could anyone tell me how EGR and Airflow sensor issues manifest themselves?

 

[DoIDon'tI]

EGR can cause a general lack of 'bottom end' torque, a 'surging' on acceleration, excessive wastegate noise, a sudden 'jerk' on acceleration, a jerky downchange from 4th to 3rd in automatic cars and in the worst cases (depending on failure mode) illumination of the engine check light.

EGR is a sore point for me - having had all of the above symptoms except the warning light I now have a collection of old EGR valves in my shed, in the end a new valve with the latest part number finally made my car run acceptably well.

Both the old valves have had the full 'strip and clean' carried out in the past, which helped for a while before the symptoms returned. The topic has been well covered on this forum, search for 'EGR' and you'll see what I mean

Only took me two years and 46K miles to get it sorted

HTH.

 

[BrianMcL]

Hi DoIDon'tI,
It progressively looses bottom end torque as it builds up towards its regen cycle but once it completes it's fine for a while. Would that be consistent with EGR issues or if it's an EGR issue should it behave in a random or consistent fashion (i.e. you never know when it's going to be down on power or it's always going to be down on power)?

A couple if independents that have had a look at it are convinced it's an airflow sensor problem.

I just can't help thinking that because the problem is so predictable the solution has to be obvious.

I've had a read through the various how to's on EGR cleaning and so forth so I'll have a bash at that - you never know, it might be the solution.

 

[DoIDon'tI]

The MAF sensor and EGR are both known to cause issues, however you would think that it would be more consistent. EGR cleaning is worth a go, one known method of testing the MAF is to try the car with it electrically disconnected - if it's better then it's the MAF.

For the car to be this sensitive to exhaust back-pressure makes me wonder if another part of the exhaust is faulty (baffles breaking down or cat problem), or whether the turbo is working correctly.

The EGR does have some effect on low-speed turbo operation so you never know, it might be worth a try. The thing to remember is that the car's performance should not vary noticeably whether the DPF is clear or full.

Good luck, and please let us know how you get on.

HTH.

 

[BrianMcL]

Obvious question and with a presumably obvious answer but I'll ask anyway.

Do I just pull the plug out the MAF?

 

[BrianMcL]

Another thought on this one.

Are there any published tolerances that the engine should operate within? For example, if it was the turbo that's the problem what should I see in ECUscan results?

Also, if it was something exhaust-related is there anything within ECUscan that would show outwith tolerance?

It's as if there's just enough pressure/power within the engine for it to operate normally when the DPF is OK but as soon as it starts to clog (presumably increasing back pressure albeit only marginally?) it starts to loose power.

And, if there's a malfunctioning sensor on the DPF might it cause the engine to gradually power down, possibly to protect the DPF itself?