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[Dom]

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

[Auto Addict]

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.

[Dom]

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.

[Auto Addict]

No, you have to feel under the scuttle, there's like a spongy material, check that it's not wet.

[Welung666]

Where are you Dom?

[Dom]

Hi, I am in Belper, Derbyshire.

[Welung666]

Not that far then. If you want me have a look for you just drop me a PM

[TheBoy]

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...

[PhilRich]

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 

[Welung666]

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

[Dom]

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!

[Auto Addict]

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.

[Kevin Wood]

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

[aaronjb]

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?

[Kevin Wood]

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