Omega Owners Forum
Omega Help Area => Omega General Help => Topic started by: mikeF on 15 June 2007, 14:10:25
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My first post here and all I can bring is problems, problems ... sorry :-/
I have a V6 estate auto on an R plate which I've driven from new and which now has 88K on the clock. Despite regular servicing, it's had all the "standard" faults - water leak, oil cooler, oil leaks from the camshaft covers (and probably more things I can't remember!) and now I have something new that's driving me crackers. It's a problem I have seen reported on other forums on the 'web, but I couldn't find a specific reference to it here ...
On odd occasions (often many months apart) over the last three years or so, the engine has failed to start. Sometimes after a few minutes cranking the starter (not continuously!!) it will spring into life and will run fine for months thereafter. There's no smell of unburnt fuel when the engine is cranking, sometimes the rev counter needle 'jumps' initially before dropping to zero and sometimes it doesn't move. The EFL doesn't flash but remains lit steadily.
On two occasions in the last year, I gave up trying to start it and 1) called my pet mobile mechanic to look at it and 2) got a friend to tow me to the local VX dealership for them to look at.
1) the car started for him next morning without any problem
2) the car started for them next morning and they reported no fault codes found by their fancy gizmo
I thought about what had changed between it not starting for me, but being ok some time later. The only thing I could think of was that I had removed the key and operated the central locking. I guessed it could be the immobilizer so when it happened again this morning, I took the key out, climbed out the car and locked the doors.
Unfortunately, when I unlocked and tried to start it again, it still wouldn't !!
So, to cut a long story sh ... ahh, too late, sorry. I tried my spare key with the same result, re-programmed the 'normal' key and that didn't help either. I then spent a while smurfing the Interweb to see if I could find some helpful information while waiting for the local VX dealers to open. About 45 mins later, I decided to give the car one more try before calling the garage ... It started on the first turn of the key and sat there purring happily while I shouted rude words at it.
One more bit of information - last Summer, a bit less than a year ago, I had a problem with the car stalling at lights/junctions after about 20 minutes of driving. VX dealer changed the crankshaft sensor and cured the problem. (So I'm disinclined to believe the current problem is caused by the crankshaft sensor).
I feel that if only I could find out definitively what signals the ECU requires to see before switching on the sparks and sending fuel to the injectors, it might be possible to verify them by measurement and pinpoint the cause of the engine failing to start.
Others have reported pretty much identical symptoms in what I read on the web this morning, but the causes and cures are rather less certain.
So, can anybody help this desperate man? Please?
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The ECU requires crank pulses from the crank sensor to initiate injectionand spark cycles...
I would say the crank sensor but, read the fault codes out and see if you get a code 19....just because the item was replaced before doesn't mean it was replaced well....poor routing of the cable will result in premature failure and we all know what mechanics can be like.
Also, for info, oil cooler failure is normaly due to in-frequent coolant changes and/or topping up the coolant using water and not a 50:50 water/antifreeze mix....
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You can read the codes on that car with a paperclip, no fancy gadgets required. My gut feeling is crank sensor, but the 19 code will confirm that.
Hope that helps
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You can read the codes on that car with a paperclip, no fancy gadgets required. My gut feeling is crank sensor, but the 19 code will confirm that.
Hope that helps
Thanks for this. So are you saying that the fault codes stored in the ECU are non-persistent and that the VX dealer couldn't see anything with the Tech2 'cos they were erased - either when the engine started ok for him, or even before that when the ignition was turned off by me?
And for the previous reply, is there an implied "only" in the sentence (The ECU (only) requires crank pulses from ...) or could there be other requirements too? Is it feasible for me to try to measure these, d'you think - given access to a test meter, or oscilliscope, or ..?
I presume Googling will uncover the "paper clip procedure"?
The help is much appreciated, thank you.
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Your problem sounds exactly like a failing crank sensor to me.
The failure is extremely hard to pin point because you don't usually get a fault code. Occasionally a 19 gives the game away but that's about it.
Basically people tend struggle with a fault like this for ages and eventually bite the bullet, pay £50 for a crank sensor and fit it and the problem disappears.
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The FAQ section covers the paperclip test.
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Like all the other here (and if Marks DTM says something, he is invariably right!) I would say crank sensor.
Guide to reading the codes is here: http://www.omegaowners.com/forum/YaBB.pl?num=1152601768
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The ECU requires crank pulses from the crank sensor to initiate injectionand spark cycles...
I would say the crank sensor but, read the fault codes out and see if you get a code 19....just because the item was replaced before doesn't mean it was replaced well....poor routing of the cable will result in premature failure and we all know what mechanics can be like.
Also, for info, oil cooler failure is normaly due to in-frequent coolant changes and/or topping up the coolant using water and not a 50:50 water/antifreeze mix....
I agree, especially as the Tacho needle moves once then nothing...
If code 19 make sure you get the right one... plugs are different.. DC
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And, Welcome! :)
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And, Welcome! :)
Thank you !! :)
And thanks for all the replies here. I'll accept the combined wisdom and go buy a crank sensor. I may have to get my pet mobile mechanic to fit it 'cos I'm not as young and flexible as I used to be !!
With exhaust systems being replaced, leaky oil seals (all three) on the diff and on the output shaft of the transmission being replaced, an aircon recharge and a 10-year service, I've spent over £1000 on the car in the last week. So would I have another one? You bet! Best car I've had - this is my second one in the sequence Cortina > Cavalier > Carlton > 5-series BMW > Omega > Omega, and I'm delighted to have found a group of fellow enthusiasts. Thanks guys.
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Mike - hopefully, now that you have found this place, the excess expense will be reduced somewhat by expert diagnosis as well as persons willing to exchange repair work for beer, as and when required!
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Mike, please forgive this blatant, but pertinent hijack...
Does anyone know the failure mode of these here crank sensors? Is it an ageing process of some kind? Mechanical (vibration?) damage? Electrical damage?
I've read some stuff on here about the wiring run being important, keeping away from zorst manifold as far as poss., so is it actually the wiring that fails? Does the sensor come with captive wires and a connector at the end of the cable?
Sorry, lots of questions, but I'm pretty sure the sensor on my g/f's car is original, and wouldn't mind being able to pre-empt problems by understanding causes. :)
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In theory because it's a hall effect type sensor it should not wear out. On the Omega I think the general concensus is that with the original wiring clamped under the hot oil cooler pipes, and not being far from the exhaust either, it's the cable that breaks down and causes the failure.
The cable is moulded into the sensor with a connector at the other end.
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Yep, sensor is fine... but Vauxhall in their infinite wisdom routed it down the back of the engine between the oil cooler pipes and the exhaust downpipes. Not a good place for wires...! ::)
Continued exposure to serious heat eventually kills them. :(
Absolute doddle to replace (on the V6) and once re-routed, won't cause further problems. :)
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Yep, sensor is fine... but Vauxhall in their infinite wisdom routed it down the back of the engine between the oil cooler pipes and the exhaust downpipes. Not a good place for wires...! ::)
Continued exposure to serious heat eventually kills them. :(
Absolute doddle to replace (on the V6) and once re-routed, won't cause further problems. :)
Also, tends to get lots of hot oil on the lead during filter changes sometimes.
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So are you saying that the fault codes stored in the ECU are non-persistent and that the VX dealer couldn't see anything with the Tech2 'cos they were erased - either when the engine started ok for him, or even before that when the ignition was turned off by me?
The codes are stored for a set time (varies depending on code). Your assumption that the dealer knows how to use a Tech2 may be a bit ambitious ;)
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Mike - hopefully, now that you have found this place, the excess expense will be reduced somewhat by expert diagnosis as well as persons willing to exchange repair work for beer, as and when required!
Hmmm .. one crank sensor fitting = how many beers I wonder? ;)
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Mike - hopefully, now that you have found this place, the excess expense will be reduced somewhat by expert diagnosis as well as persons willing to exchange repair work for beer, as and when required!
Hmmm .. one crank sensor fitting = how many beers I wonder? ;)
Have you done the paperclip test yet?
Hatfield is a little far for me I'm afraid, but you will have no trouble replacing crank sensor if thats the problem :)