Northern Auto Tech - ECU and Blue & Me Repairs

Technical Croma "misfire"

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Technical Croma "misfire"

Cromatix

Cromatix

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Feb 25, 2013
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Felicitations Fiat Fans

I've just got a Croma 1.9JTD 150 and it's making me very anxious. It's a 2006/06 has 74000 miles and has a string of symptoms that say "EGR valve", but it has a new EGR valve and I've taken it apart and checked it and it all seems OK. I've been reading this wonderful forum for hours and have ended up like a car hypochondriac (feeling that my car must have all the most expensive ailments known) so I have decided I had better be brave and join up and see if I can benefit from your collective experience on these things. I wonder if any of you can point me in the right direction:

Symptoms:

  • Low torque/power at low revs, but plenty comes suddenly when you floor it. It's particularly bad in first gear so it seems that it's somehow load related.
  • Intermittently "misses" - typically when not under load
  • Exhaust makes a farty kind of noise (like it's got a Vauxhall Corsa boy racer exhaust thingy.) This is over a fairly narrow rev band when under load and has begun since the "low power" symptoms and may not be related.
  • Poor fuel economy (around 37mpg on A and B roads)
  • Judders and fires unevenly on starting for the first few seconds, then evens out.
What I have done and what I think I know: :confused:

  • I have checked the EGR valve - it is new (months old), clean and functional (according to MultiEcuScan)
  • Cleaned MAP sensor - now a little better at low revs, but still pretty rubbish.
  • I have driven it quite hard to try and "blow out the cobwebs" in case the previous owner was too gentle. No change.
  • The OBD had stored errors for EGR and two others. I tried to clear just the EGR one and managed to clear all of them :( and now I can't remember them, but I have driven it since and no new codes have been stored.
  • MultiEcuScan reports what looks like decent turbo boost
  • The DPF seems to have been regenerating and is being reported as "normal clogginess."
From what I've read so far, there are a large number of suspects in this investigation but I'd really appreciate some guidance in eliminating them from my enquiries. I'm reasonably technical but don't have much of a background in cars.



Thanks!
 
Hi Cromatix.

Couple of relatively pain free things to try before things get technical:
1) Unplug the maf and see if that helps. If not plug it back in and;
2) Blank the egr off completely and see if that helps. If not remove the blanking plate (but buy and fit a swirl mod gasket off ebay anyway) and;
3) Check the air filter for physical damage / blockage and the oil service indicator in multiecuscan.
 
I'm no technical expert but I have the same engine as you (mine's an auto). With regards to the juddering and uneven starting I had this problem before Christmas. I thought it was the glow plugs and replaced these but it persisted and I then changed the battery which completely cured the problem (see post below from S130 which alerted me to this issue). Make sure you wait a few seconds for the glow plug light to go out before firing. If you're going to change the battery make sure you get one that's the right size (plenty of info on here).

With regards to your other problems there are others better qualified to help than me but I was just wondering what your DPF clogging % was. I know that mine shows normal clogging right up to about 86-87% which is as high as I've ever seen it and at these levels it can affect performance significantly (however I can't see that this would explain the sudden pick up at higher revs)

https://www.fiatforum.com/croma-ii/310379-possible-battery-imminent-failure-warning.html
 
Thanks so much for the replies. They're all things I've wondered about.

I'm going to try your suggestions, BrianMcL and see how we get on, then check the battery state if we've still got issues. I seem to remember the OBD reporting 14V but that was while the engine was running and may not be that indicative of the battery health.

Unfortunately I'm not going to have time until tomorrow evening.

Regarding DPF: I'll need to look again for the % as it just did another regeneration yesterday (I'd been anxiously watching the MPG anyway, and when it dropped to below 20 and was smelling really hot when I parked yesterday I thought that's what it must be) - the fuel economy is back to what it was when I drove it today so it wasn't just melting down...<phew!>

I also wondered if it could be a split turbo hose as that's been mentioned here before and may contribute to the noise, but I don't know which hose/where to look.

Thanks again for taking the time to reply. I appreciate it. (y)
 
Hi Cromatix.

I should have mentioned just in case that the oil % degradation is really a measure of how healthy the engine thinks the oil is - sounds bizarre but if multiecuscan reports the oil as 85% degraded and 40000Km to next service that's actually a very good thing as the oil's got 85% of it's expected life left.

And defo get a swirl mod gasket if you haven't already ;)
 
The oil and oil filter were replaced less than 2000 miles ago so they should be fine. The EGR valve was replaced at the same time. If the EGR swirl gasket is the one with the four holes in it, it already has it. When I had the EGR valve off, I took the solenoid off the valve casing and it's nice and clean in there so I'm fairly sure it's working, but I see the point in blanking it to be sure. Hopefully I'll get a chance to make up a blanking plate tomorrow and try it (after I've tried disconnecting the MAF sensor which should only take minutes).

I can't see any mention of battery replacement in the service history so it must be approaching end of life. I do notice that the headlights change in brightness with the engine speed which my old Marea never did! I'll attempt to check the battery when I've done the cheap and easy things that have been suggested.
 
My 2.4 takes about 5 miles to regen. I find it better to keep the revs up, 2000 to 3000 if possible. If it was hot when you stopped it might not have finished the regen. On the oil change there are 2 mileages to reset, one is oil condition, often missed by service garages.

Plenty of info on the 1910 on alfaowner.
 
If everything's in as good a nick as it sounds then we might have an engine power problem that isn't egr based.

You'll be able to tell whether the oil change counter was reset when it was changed as it should say 95% or thereabouts.
 
Might it be a swirl flap problem?

Ivanjuaric's "strange juddering" post from 9th Jan 13 has more info on that problem / solution.
 
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Well, I've just been out with MultiEcuScan and had a quiet word the with car and got some new answers and a few more questions:

Firstly, keithglos, the DPF did regenerate the other day and I think it's done it properly. It's currently reporting 22.66% clogged (to the nearest hundredth of a percent ;)) The oil condition is reporting 92% so we're happy with that I would think. The oil change odometer reading however is saying 10705km. I can't tie that up with anything in the service record which says it was changed at 73,288 miles which is 118,200km or just over 2000km ago. If it reads distance since the last oil change, it still doesn't tie up with any previous change. I doubt that's much to worry about is it?

More interestingly, I got a copy of eLearn and had a look at the procedure for testing the MAF sensor which involves checking the reported air flow at different engine conditions. Annoyingly MultiEcuScan reports the MAF readings in mg/i and the procedure is asking for them in kg/h, but I've found enough info to work out that it's measuring OK at idle. What is odd though is that when I push the accelerator, it goes down. At first I thought that must be a fault, but thinking about it now, because it's per intake rather than per hour, it could go down - it just means less air per cylinder. Anyway, to avoid too long a story and some unpleasant maths, I unplugged the MAF sensor and took it for a drive. It was MUCH better! No misfire, pulls at low revs. I'm not sure it's absolutely right but it's certainly a huge step in the right direction.

Soooo.... What now? I've had a look at Ivanjuaric's post - it looked for a while there like it might be alternator/battery. I doubt mine is related to the ESP/ABS. Maybe I had better get the battery checked next. It seems I won't be able to test it properly with the equipment I've got.

Also, the question that's going through my mind is "if it works without the MAF sensor, why do I need it?" and is it OK to drive it to work tomorrow without it (40 miles round trip).

Thanks for your help on this.
 
Cromatix said:
Well, I've just been out with MultiEcuScan and had a quiet word the with car and got some new answers and a few more questions:

Firstly, keithglos, the DPF did regenerate the other day and I think it's done it properly. It's currently reporting 22.66% clogged (to the nearest hundredth of a percent ;)) The oil condition is reporting 92% so we're happy with that I would think. The oil change odometer reading however is saying 10705km. I can't tie that up with anything in the service record which says it was changed at 73,288 miles which is 118,200km or just over 2000km ago. If it reads distance since the last oil change, it still doesn't tie up with any previous change. I doubt that's much to worry about is it?

More interestingly, I got a copy of eLearn and had a look at the procedure for testing the MAF sensor which involves checking the reported air flow at different engine conditions. Annoyingly MultiEcuScan reports the MAF readings in mg/i and the procedure is asking for them in kg/h, but I've found enough info to work out that it's measuring OK at idle. What is odd though is that when I push the accelerator, it goes down. At first I thought that must be a fault, but thinking about it now, because it's per intake rather than per hour, it could go down - it just means less air per cylinder. Anyway, to avoid too long a story and some unpleasant maths, I unplugged the MAF sensor and took it for a drive. It was MUCH better! No misfire, pulls at low revs. I'm not sure it's absolutely right but it's certainly a huge step in the right direction.

Soooo.... What now? I've had a look at Ivanjuaric's post - it looked for a while there like it might be alternator/battery. I doubt mine is related to the ESP/ABS. Maybe I had better get the battery checked next. It seems I won't be able to test it properly with the equipment I've got.

Also, the question that's going through my mind is "if it works without the MAF sensor, why do I need it?" and is it OK to drive it to work tomorrow without it (40 miles round trip).

Thanks for your help on this.
Click to expand...
Yeah, it'll be fine. Not a long term fix though. The engine management light will come on until you reconnect and will stay on for 3 driving cycles afterwards.
 
Thanks. I've driven two days with it disconnected now. It's better than it was, but it's not right. It no longer "misfires" but it doesn't pull properly at low revs either and the fuel economy is still depressing. I have looked at taking the MAF sensor out to clean it but it doesn't look like it'll be that easy - I guess Bosch want you to buy a new one. The bands that hold it don't look re-usable either so I'll need to get some jubilee clips before I start . I'm going to have another go at it at the weekend if I can.
 
If it is the MAF, and I guess it might not just be the MAF, eurocarparts have an unbranded one for about £120 and they've got either 20% or 25% off different parts this weekend.

The original Bosch is much more expensive.

Good luck.
 
My feeling is that there are probably at least three things wrong:

1) MAF sensor
2) Battery
3) Hole in exhaust/induction somewhere

I've got the battery on order, along with jubilee clips to do the MAF sensor. I'm going to try the existing one again with the new battery and if it still gives trouble, have a look at cleaning it, but failing that... £££

Actually, I notice that I still haven't checked the air filter as you suggested originally. I've been assuming that it was changed at the last service, but the screws look really rusty like they haven't been budged for a while, so I'm beginning to have my doubts. Another job for the morning.
 
If you change the MAF sensor, it is recommended that you do replace the air filter at the same time.
Be wary of non Bosch sensors. I bought a QH one which cross referenced correctly, but it wasn't recognised by Croma's massive brain. No return on MAFs so out of pocket as well.
Hope this helps
CJLAR
 
cjlar said:
If you change the MAF sensor, it is recommended that you do replace the air filter at the same time.
Be wary of non Bosch sensors. I bought a QH one which cross referenced correctly, but it wasn't recognised by Croma's massive brain. No return on MAFs so out of pocket as well.
Hope this helps
CJLAR
Click to expand...

Seriously!!! That's a disgrace! Surely MAFs are just like anything else and have to be fit for purpose. A MAF that isn't recognised by the car clearly isn't and shouldn't have been sold as compatible.
 
I'd have to say I agree with BrianMcL on that one. There must be some legal buyer protection for that kind of thing.

If it comes to it, I will probably be buying the Bosch one anyway.

I've been out and checked the air filter this morning. The screws were really rusty so it didn't look like it could have been opened recently, but the filter is new and clean, as is the pipe around the MAF sensor.
 
Ah yes the infamous MAF!!! From my experience this is the fall back diagnosis of all Fiat Garages when they haven`t a clue whats wrong with a Croma. :bang:
What i have found is that Fiat have made the MAF an exchange part due to the great "demand" and as it will be easy to replace the innards , which are electronic parts, and make a pretty penny.
I have taken the advice of an "old sweat" at my independant I use and swapped to a K&N air filter which I clean every autumn, since then I have had no MAF probs. His theory is that a damp,mucky paper element will cause condensation in the area of the MAF as the engine cools down and the nights get colder , this causes the MAF electronics to corode.
 
Well, this thread is pretty old now, but I'm still having the same trouble and it's getting a bit more mysterious.

I've changed the battery and that's made very little difference. I've been running with the MAF sensor disconnected and that's fixed the hesitancy, but there is still the engine light on because of that.

Because of the noise like leaking exhaust or induction, I took it first to an exhaust place and had the exhaust checked. They found no problem. Working on the hypothesis that there is a leak in the turbo/intercooler pipe somewhere that is affecting the MAF sensor readings, I booked it into my local garage - that was some time ago as they're very busy (they're a good bunch - I regard them as competent and trustworthy). I've just got it back and they couldn't find anything wrong with the induction circuit. They tried a new MAF sensor and it made no difference - that's a relief in a way. Because they couldn't fix it they didn't charge.

So... here's where it stands:

Symptoms:

  • the car makes a noise like leaking exhaust or induction noise when under load between 1500 and 2000rpm
  • There is little power at low revs then it comes in with a bit of a thump at some indeterminate point (it's not very consistent). It's a bit worse when warmed up.
  • The fuel economy is not too good (maybe 15% down on what it should be)
  • If the MAF sensor is connected, you get hesitancy/misfires.
What's been checked:

  • Battery replaced
  • Cleaned MAP sensor - small improvement
  • Air filter is new and quite clean
  • Exhaust pipe is apparently in good condition
  • Garage can't find anything wrong with the turbo/intercooler hoses
  • Garage tried new MAF sensor - no change - back to old one.
I've got a copy of MultiEcuScan and tried to work out what's going on, but it's not storing any error codes except when the MAF sensor is disconnected (codes are for the MAF sensor and intake temperature sensor).

I'm not entirely convinced I can rule out leaking pipes as there is definitely a noise, and this would explain why the MAF sensor could be sending wrong data to the ECU and therefore getting the fuelling wrong. The problem is, how to find it since it only happens under load and you can't stick your head under the bonnet when powering along the road...:confused: Any ideas?
 
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Oh no! I've just been browsing around here and on the Vectra-C forum (same engine) and the swirl flaps have been implicated in some posts with similar symptoms. Just went and had a look and the link bar for the swirl flaps is detached. I expect that'd do it! Now to work out how to fix it, given that it's likely to be worn out and the "dealer" fix appears to be to replace the inlet manifold... :(
 
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