Omega Owners Forum
Omega Help Area => Omega General Help => Topic started by: terry paget on 29 October 2016, 09:34:09
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KOV 2.5 petrol mnual estate
Returning from Oxfordshire last night, joining M4 from A34, came to rest at red light at the roundabout and the engine cut out. After haf a minure cranking the starter is stuttered back into life again. I drove it the 60 miles home, much to my relief.
I suspect crank sensor. I had had similar failures on all my 2.5s, at least this one got me home. No cable routed up the brake pipes, so mine is original, so has done170,000 miles and 16 years service. I am tempted to change it. I do not carry a spare, like some fellow oofers.
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Probably not crank sensor, as it started relatively quickly.
What does paperclip test reveal?
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MAF is a distinct possibility. Although I would wait until the fault is a common occurrence before replacing it.
When mine failed, the car wouldn't idle or restart without a touch of throttle. This only happened when it had been running for sometime; it wasn't a problem in daily use. Disconnecting the MAF put the EML on, but stopped the problem. That was enough for me to replace the MAF with a spare. If you've got to buy one, I would recommend a more technical diagnosis by checking the live data first.
Thinking about it, checking the data should ALWAYS come first, as just swapping parts is a terrible way of fixing faults.
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Thanks for the quick response, chaps.
Paper clip test engine running reads 12 12 12 12 12 12. 12 is not listed in code table. 21 is throttle position sensors voltage high, but it definitely is 12.
MAF sensor it could be. Had one dodgy on my first 3.0, it would stall occasionally and drove me mad. Finally got the tip on the Catera forum, and the test - unplug it and see if it cures the fault; it did.
I wonder if I have a spare.
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Before changing MAF, try and get a live data reading off it.
IME, unlike the 2.6/3.2 MAF, 2.5/3.0l MAFs rarely gradually fail, they tend to work fine and then don't work at all.
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Before changing MAF, try and get a live data reading off it.
IME, unlike the 2.6/3.2 MAF, 2.5/3.0l MAFs rarely gradually fail, they tend to work fine and then don't work at all.
On my 3.0 the engine would cut out without warning occasionally - every half an hour or so. It drove me mad, I changed everything else I could think of, all to no avail. This went on for six months. I had not joined this forum then, would that I had. On my Senators the MAFs gave no trouble at all, they were big flaps and a carbon track resistor arrangement.I do not know how Omega MAFs work, but they are less reliable.
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Unplug the Maf and see what happens... if it improves matters, then the Maf is toast, if it doesn't, then it's working as it should :y
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I do not know how Omega MAFs work, but they are less reliable.
Hot wire principle. Pass current through it, and the mass of air cools it, and as its resistance changes with temperature...
(that's slightly simplified, but that's the principle)
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I do not have a device that reads live data, so have now swopped my MAF for a spare. If stalling recurs I will report back.
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I do not have a device that reads live data, so have now swopped my MAF for a spare. If stalling recurs I will report back.
Unplugging is a fairer test as it isolates the problem... swapping introduces unknown variables into the diagnosis...
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I do not have a device that reads live data, so have now swopped my MAF for a spare. If stalling recurs I will report back.
Unplugging is a fairer test as it isolates the problem... swapping introduces unknown variables into the diagnosis...
I understand that. My Opel 2.5 saloon (car that popped a rear shock into the boot) died suddenly and completely without warning, luckily near home. I towed it home, changed the crank sensor and all was well. I did not want to risk that happening.
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Car will still be driveable with maf unplugged as ecu will make assumptions based on rpm and throttle position ;)
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Car will still be driveable with maf unplugged as ecu will make assumptions based on rpm and throttle position ;)
I beg pardon, I was talking rubbish. As you say, if fault recurred all I needed to do was unplug the MAF sensor and proceed.i
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Would have been nice to see trim values before the MAF was swapped. But never mind.
With 6 Omegas, a capable diags machine might be money well spent?
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Would have been nice to see trim values before the MAF was swapped. But never mind.
With 6 Omegas, a capable diags machine might be money well spent?
Can you recommend such a device, bering in mind 2 of my cars are not OBD2 compliant?
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After a week of good behaviour in local runs this car failed again on my Friday run to Oxfordshire. After a 65 mile fast run to Wantage I parked for 15 minutes, then engine refused to start. This engine normally starts first time. After six 5 second starter squirts I paused, then gave a 20 second squirt with throttle wide open in case it was flooded; still no life. Panic was setting in. I opened the bonnet and unplugged the MAF sensor. I cranked the starter, engine started. Phew!
I preceeded to my first call, 2 hours chatting to old friend. Then drove to Culham laboratory to play table tennis. Later I drove to Cherry Tree, Steventon for a meal. Finally I drove the 70 miles home.
What is the fault. Crank sensor? Battery? Please advise.
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Maf ;)
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I would be surprised if the MAF affected starting. My money's on the crank sensor.
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If you are passing the Oxfordshire/Northamptonshire border, I'll happily plug the tech2 in...
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I would be surprised if the MAF affected starting. My money's on the crank sensor.
I'm thinking similar...
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I would be surprised if the MAF affected starting. My money's on the crank sensor.
I'm thinking similar...
All the other faffing may well have given it a chance to get its shit together...
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Thanks for advice gentlemen. I have now changed the crank sensor. Will report after next Friday.
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Happy to report that yesterday's 200 mile run, to Didcot, Wantage and Culham Laboratory, passed without incident - no stalling, failing to start, or other engine misbehaviour - so it looks like changing the crank sensor has cured things. I thank all for their advice.
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Happy to report that yesterday's 200 mile run, to Didcot, Wantage and Culham Laboratory, passed without incident - no stalling, failing to start, or other engine misbehaviour - so it looks like changing the crank sensor has cured things. I thank all for their advice.
fingers crossed that's the end of the problem :y