Engine Management Light - Ignition Coils

[TashRy]

Hi there, after some help or ideas. My engine management light came on, took to garage to get it checked out told me 1 of the ignition coils was faulty. Had it replaced, same problem occurred with the new coil, was replaced again. Once leaving the garage they told me the car was registering another faulty coil.

I decided to look into buying a set of 6 and replacing the whole lot, and also replaced all 6 spark plugs. This was done today, had the light reset and was driving fine and I was :-) half hour later the engine management light is back on and it's juddering again and mis-firing exactly how it was before the coils were replaced.

Any ideas?? Thanks

[ColinBarber]

coil packs don't fail all at once, I would have recommended that the supposedly faulty coil pack was moved to a different cylinder to see if the fault code followed it - that way you can further diagnose the issue without having to purchase items.

I suspect you have a faulty fuel injector. These tend to produce random misfire error codes which get incorrectly diagnosed as coil pack faults. Firstly get the resistance of each injector measured, one may obviously be faulty. Otherwise get each one bench tested to make sure it is working correctly, or just trial and error swap each one out until the fault is found.

[TashRy]

Thanks for the info. Is it likely to cost a fortune to get the injectors looked at? I should have asked the question before paying out for 7 coils and 6 plugs and labour!!

[ColinBarber]

I think they are quite expensive new from Lexus. Scrap yards seem to charge around £20 to £40 each.

To check the resistance should take more than 30 mins as they don't have to be removed. Sometimes they only show up faulty once they are hot.