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SteveBalmer's Achievements


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  1. Hello, My 2008 C4S (60k miles and fully serviced) has been giving me an issue for the last few weeks, prior to that no related problems at all. It started a few weeks ago with an amber engine management light coming on around 2 minutes after starting the car from cold. It is fine at startup with the engine running nicely, but after arouind a couple of minutes the light comes on and the engine starts to run lumpy BUT when i give it any increase in accelerator, it becomes smooth and runs perfectly again - it just seems to be very unhappy with my foot off the accelerator and the engine at idle where it drops to around 500-600rpm and runs lumpy with the engine management light coming on. If i carry on driving and the engine gets 'up to temperature' then the idle comes back to it's regular 900rpm and it ticks over perfectly. I have my own code reader and the car was showing the following codes; P0040 - Oxygen sensors upstream of cat. conv. interchanged (Signal implausible) P0300 - Misfire summation fault (exceeds limit value) P0301 - Cylinder 1 misfiring (exceeds limit value) P0302 - Cylinder 2 misfiring (exceeds limit value) P0303 - Cylinder 2 misfiring (exceeds limit value) So, based on previous research on this issue, I changed all 6 coil packs, all 6 spark plugs and all 4 oxygen sensors (both the upstream and the downstream sensors on both sides). This has not improved the issue however, and still the engine starts fine and smooth, after it has run for a couple of mins, it audibly drops revs, becomes lumpy and engine light comes on, but if i give it some gas, it runs perfectly again and the engine light goes out. I should also mention that during this time of issue, it has also had an MOT and passed with perfect emissions. In my old fuel injection cars, they used a cold start valve, which was like a choke for fuel injection engines and gave the engine a bit of extra fuel to start and warm up - could this be something similar and the two minute period is when the cold start valve closes and suddenly the engine is starved of fuel and runs awfully until i use the accelerator to give it back more fuel? However, why only one bank of cylinders (1,2 and 3)?? I am struggling with this one and hoping someone may have had this or knows what's going on? Thanks, Steve
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