Omega Owners Forum
Omega Help Area => Omega General Help => Topic started by: Dom on 24 August 2010, 16:50:13
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I have had a fault developing on my Omega 2.2 (2001) over the past few months. The Engine runs on 3 cylinders, occasionally 1 in 20 times I use it runs fine for the first 5 miles or so, then goes back to running on 3 cylinders.
The engine management light has come on and I had the following fault code:
p0110 - generic cylinder 3 missfire
I have replaced the MAF, crank angle sensor, plugs and coil pack to know avail. I have ruled out head gasket too.
I have replaced the cables from the ECU to the back of the coil pack; as a result I now have a connector block at the ECU where the cables come from the pug connecting to the ECU, this has the 8 feeds coming from the ECU, each cylinder has 2 cables from the plug of a smaller gauge to the cables that plug into the back of the coil pack. I assume because there is not enough room in the plug for the full gauge cable and so 2 pins per cylinder used from the ECU. From the connect back of the connect block each cylinder then has 1 cable.
I have identified it is number 1 cylinder that is not sparking. I have also been able to measure the outputs from each of the signal cables coming out from the ECU, by using a volt meter on the connecter block the the battery earth. There is a 13.6 volt signal coming out from cylinder numbers 2,3 and 4, but only 5-6 volts from number 1. I have therefore assumed that the ECU has had it. I bought a replacement, with transponder and chip off ebay for £175 claimed to be off a working car. However, with this I get the exact same fault. The only difference between the ECUs is that thereplacement ECU lights up the engine management light with the spanner on it, where as the original lights up the other light which is just an engine. No codes are now showing?
Does anyone know if this is a common ECU fault in the 2.2 and if so, have I just brought another duff one with the same fault? Any Ideas welcome, the car is heading for the scrap yard at this rate!
Thanks in advance - Dom
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With this wet weather, feel under the scuttle, at the back of the engine, over the eco strip.
Is it soaking wet?
If it is, it's probably, dripping onto the coil pack connector at the back of the eco strip, causing a short and misfire.
Just a thought.
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Hi autoadict, no, there is no water on the back of the coil pack connecter, I have also checked for oil in the spark plug well. Dry as a bone.
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No, you have to feel under the scuttle, there's like a spongy material, check that it's not wet.
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Where are you Dom?
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Hi, I am in Belper, Derbyshire.
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Not that far then. If you want me have a look for you just drop me a PM :y
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What code reader, as its talking utter boollax
P0110, from memory is MAF/air temp fault.
Can't really diagnose more until the ECU thinks everything is OK, as some of these limp modes do work in mysterious ways...
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What code reader, as its talking utter boollax
P0110, from memory is MAF/air temp fault.
Can't really diagnose more until the ECU thinks everything is OK, as some of these limp modes do work in mysterious ways...
Yep, those codes on the 2.2 are:
P0110 Intake Air Temperature (IAT) Signal Voltage High
P0110 Intake Air Temperature (IAT) Signal Voltage Low
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I am taking a joyride up to Belper sometime this week, see if I can't clear this one up. I'll update this once I've been :y
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Hi, sorry! I got the codes mixed up. I did get the P0110 code which was MAF sensor. This led me to replace it. The other code was P0303. When I first started getting the fault I was getting all sorted of codes. I was advised to replace the crank angle sensor on the basis that when this goes it can lead to lots of codes being generated erroneously. I have replaced that too.
Hopefully Welung666 will be able to work some magic!
Thanks all!
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Crank Sensor rarely fails on a 2.2, indeed, I've heard that it will run without the crank sensor.
It's beginning to point to the cam sensor, common fault on 2.2's.
If it is, make sure you only fit a genuine one from a Vx dealer, from anywhere else, and you will have the same problems.
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Just a note to say that, once the ECU has identified a misfiring cylinder, which it has if it has logged a P030x code it will shut down the injector output for that cylinder to prevent cat damage.
I would have thought it would still spark, but you never know?
Kevin
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I thought - and I could be wrong in reference to the Omega, as I'm working on knowledge of other OBD-II systems - that the only way the ECU 'knows' there's been a misfire is via the feedback circuit on the individual coils .. in which case it wouldn't be sparking, right?
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I thought - and I could be wrong in reference to the Omega, as I'm working on knowledge of other OBD-II systems - that the only way the ECU 'knows' there's been a misfire is via the feedback circuit on the individual coils .. in which case it wouldn't be sparking, right?
It can be done via the knock sensor too, and by looking at acceleration of the crank around the ignition event. I don't know how the system on the Omega works, but I know it will detect cylinders that misfire due to lack of fuel, so it's not purely based on whether the spark was generated.
Kevin
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It can be done via the knock sensor too, and by looking at acceleration of the crank around the ignition event. I don't know how the system on the Omega works, but I know it will detect cylinders that misfire due to lack of fuel, so it's not purely based on whether the spark was generated.
You know I'd never thought of doing it that way.. I suppose the knock sensor would see 'quiet' during a non-ignition event, and the crank acceleration wouldn't be as high (although that's damped by harmonic dampers on a lot of engines - I don't know about the 2.2 on the Omega, mind.. does it have a rubber ring in the crank pulley?).
Interesting.. thanks - you learn something new every day, as they say :)
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You know I'd never thought of doing it that way.. I suppose the knock sensor would see 'quiet' during a non-ignition event, and the crank acceleration wouldn't be as high (although that's damped by harmonic dampers on a lot of engines - I don't know about the 2.2 on the Omega, mind.. does it have a rubber ring in the crank pulley?).
Interesting.. thanks - you learn something new every day, as they say :)
Not sure about the 2.2 but on the V6 the reluctor for the crank sensor is on the crank itself, so no damping there. I imagine the 2.2 is the same, based on the sensor location.
All depends how intelligent the ecu is. There was a time when they had very limited processing power so very little diagnostics could be built in. Knock sensor triggers were analogue, for example, so you couldn't tell the difference between knock, normal ignition and no ignition.
Nowadays you can cheaply build in very precise timing and analysis of waveforms coming from the sensors.
In fact, knock sensors themselves are probably on their way out: http://delphi.com/manufacturers/auto/powertrain/gas/ignsys/ionized/
This type of technology allows you to measure where in the engine cycle the "peak pressure" is occurring, and the ignition timing can then be adjusted to get the best from whatever fuel you are using.
aaanyway, back to the 2.2 Omega. ;)
Kevin
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Hi all, thanks for your help so far.
I have confirmed that there is no spark to number one. I did this by taking out the coil pack with the spark plugs in, earthing them to the battery with jump leads and turning the engine over. Sparks from the rest but not number one. I had wondered about the cam sensor as it seem ls resonabky easy to get too.
Glad to hear that it will cut the fuel too as a was concerned I would be wrecking the cat. Although I seem to recall the plug being wet? That could have been when the fault was intermitant though. It is now more or less a perminant feature!
When CAM sensors fail do they tend to fail gradually as per the fault I have?
Also, what's the Knock Sensor?
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Hmm. Puzzling. Are you absolutely positive that the coil pack is good and the connections to the coil pack primaries from the ECU are sound?
The P303 code you had is related to cylinder 3 - so has it moved to cylinder 1? If so, what component change caused that? I wonder if you have 2 faulty coil packs, with a different pot misbehaving on each?
A crank/cam sensor issue would not affect a single cylinder, IMHO.
Kevin
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Cam sensor will fail gradually on 2.2. at least from my experience. I have a troublesome one and it it still works. Causes a problem once in every two months and even then after a restart works normally
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this is probably not the cause but this has happened to me on a ford with identical intermittent fault wire in injector plug on affected cylinder was slightly pulled into the plug caused by pulling the wires when removing
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Firstly a big thanks to Welung666 for taking the time to come over a take a look at my omega. Top man! Turned out to be the coilpack at fault! Very frustrating as this was one of the first items I changed months ago. It does expain why the missfire changed from pot 3 to pot 1 I just never made the connection that it happened after changing the pack. I feel a bit daft having spent months trying to resolve the issue. Learnt a lesson about not just assuming a repacement part will work even if sold as a good one from a Vauxhall specialist breakers though! I still need a coilpack as the one I tested it with was from my uncles car. If anyone has one for a 2.2 let me know. I also have a known good spare ecu which will be heading for eBay!
Thanks to everyone for your help I am looking forwards to driving on 4 cylinders again!
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Just got home and having a nice cold, ice cold can of 'wind down' :y Very nice to meet you Dom, you'd already done a fair bit of work trying to narrow it down, mostly misleading unfortunately thanks to some of the bad advice given on 'the forum we can't mention'. Still, we got there ;) :y