AUA 1.4 Random misfire
- Thread starter enrih
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- 1.4 petrol aua diagnostics
What physical condition is the coil pack? On my AUA, even though it looked o.k when in situ, once I had taken it off it was obvious that the underside of the casing was badly cracked where there is a lot of heat from the engine, and insulation had shrunk so that sparks were earthing straight onto the engine block instead of inside the cylinder, especially in damp weather (that we have routinely in Scotland!). I had also replaced spark plugs and cables (and injectors, throttle body and EGR), but the big improvement came with a new Bosch coil pack. No misfires since in over a year - before changing this, it was more than one misfire per minute!
When I first got the car, all the advice I had on fluctuating revs was dirty throttle body and EGR, and indeed, fixing these resolved the revs variation, but did not eliminate the misfire. There are some comments elsewhere that varying idle can also be dependent on air leaks in the pipes leading to the induction system so the mixture is badly calculated, so maybe also worth checking your induction pipes for cracks etc.
When I first got the car, all the advice I had on fluctuating revs was dirty throttle body and EGR, and indeed, fixing these resolved the revs variation, but did not eliminate the misfire. There are some comments elsewhere that varying idle can also be dependent on air leaks in the pipes leading to the induction system so the mixture is badly calculated, so maybe also worth checking your induction pipes for cracks etc.
