Omega Owners Forum
Chat Area => General Car Chat => Topic started by: Kevin Wood on 08 January 2018, 16:24:16
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As I mentioned a few weeks back, my brother has a V50 2.0D which is giving him some issues.
I had a look over the weekend. Unfortunately, it's been "Motor Traded" to the tune of about £2k before I got a look in, so no doubt that has caused some issues which need to be corrected before the real diagnosis begins. ::)
Symptoms are that it "surges" a bit under light load around the "normal" driving speed range (1.5k - 2.5k RPM). Often it will slip into limp-home with very poor performance (i.e. no boost) until restarted, whereby it recovers.. for a while.
It starts and idles perfectly fine. On full-bore acceleration the performance is probably about right and it pulls smoothly. No nasty noises, smells or smoke over and above the usual.
On taking a look at it, I discovered the following:
Intake air temperature sensor trouble code, and reads constant-30 Deg. C on live data. This is the post-turbo sensor in the intake manifold. Looks like a little bead thermistor that's completely open circuit. Would have been eliminated by now if the muppets had sold me the right part. ::)
Apart from the above, ECU is happy.
Couple of connectors left off, Breather pipe disconnected from crankcase, some signs of bodging of the wiring around the DPF pressure sensor, which looks new. Yep, it's been in the hands of some muppets. None of this appears to be causing any issues, and didn't help once corrected.
Oil level is about 20-25mm above the max mark on the dipstick. I suspect some fuel has got in there! :o
I can imagine the limp-home issues might be to do with the temperature sensor, in that the ECU gets nervous when it's been on boost for a little while without induction temperature feedback and stops play, but it really doesn't seem to be the whole story.
I can't help thinking the surging under light load might be a fuel or boost pressure control issue. I've heard that fuel pump issues on these can cause the oil in the sump problem, and might cause fuel pressure fluctuations. On the other hand, fuel in the sump has also been blamed on failed DPF regenerations, and the latter has, apparently, been recently replaced (although god knows why they didn't sort out the oil level issue).
Surging manifests itself as a regular about 1 Hz cycling of torque output. If you hold it at about 2.5 K RPM fast idle, you can also see and hear the revs fluctuating +/- 200 RPM or so about once a second. You can hear the turbo whine cycling up and down in pitch a little at this rate too. Sticky wastegate / vane actuator perhaps? :-\
IAT sensor will be replaced ASAP, along with an oil change and correction of level. Any further ideas?
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Take the manifold pressure sensor off, clean it really well and make sure where it connects to the manifold is clean to.
They have a habit of crudding up and getting slow to respond....so it goes for a slight over boost , turbo gets backed off, repeat and sometimes it over boosts and trips to safe mode.
Buts sounds like a whole heap of bodgery has gone on!
Also, its very worthwhile cleaning the EGR whilst you have it.
Be aware, chances are that it will not regen the DPF whilst the fault light is illuminated.....so new DPF or not, it may well be pretty clogged.
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Thanks for the thoughts. I took the pressure sensor off while I was fiddling, and it and the part of manifold where it connects looked OK, but I'll give it another check when I get the right temperature sensor. IIRC, it had quite a small hole where it samples pressure, so possible it's got restrictive.
Will have a look at the EGR too. :y
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What year is car ?
What diagnostic equipment you have ?
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The car is a 55 plate and I have borrowed a VIDA / DICE setup. :y
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Maybe someone was messing with remap/dpf delete and goneed wrong
I do have this happen often
What reading you get at dpf ? Did you perform active test on egr solenoid?
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I had another look last night. Changed the oil and filter and corrected the level. What a mess! The engine has certainly had a good flush. ;D
My oil pan, that normally comfortably takes the oil from a V6 with loads of space, would have overflowed badly if I hadn't had another one to hand, all this from an engine with an oil capacity of 4.8 litres. :o
Since I reconnected the breather the intake system has clearly been ingesting a bit of oil. Makes me wonder if it was disconnected deliberately.
Changed the temperature sensor but, not surprisingly, the fault remains. I had a good look at the boost pressure sensor, and its inlet looks clear. Gave it a swill around in some alcohol and put it back. no change.
Unfortunately the diag software died so I wasn't able to get in and check anything. >:(
Had a good look underneath, though. DPF hasn't been changed, or disturbed, recently. I doubt it has been deleted as they have had the car for a good few years and it has only recently started playing up.
Didn't have time to remove the EGR as it's well buried behind the head.
Problem is they live 45 minutes away, have a 2 year old and a zero year old and the only other transport they have is a sparky's van, so it's difficult to get a decent amount of time to play with it.