Rough idle and engine light

[Sharpy1975]

Hi all

So....jumped in the car to day and was welcomed with rough idle and engine shaking. Took her around the block and engine light came on.

Called out the AA and scanner pulled up a few unknown codes. But the chap seemed to think a coil had gone. He managed to pick up one before parts closed. Replaced, still rough but another coil seemed faulty....as when removing no difference in engine sound.

Does this sound right?

Codes were:

2743
2742
274e

Off to pick up another coil tomz.

 

[Jfgoldfish]

Which engine are we talking about?

 

[Sharpy1975]

3.0

 

[colb]

a bit of google searching revealed
2743 Misfire cylinder 1
2742Misfire Cylinder 5
274e Multiple misfires multiple cylinders
These were on a E46 car thread here https://www.e46fanatics.com/threads/rough-idle-misfiring.1271601/

Yours sounds like bad coils, just check there is no oil in the plug wells indicating bad leaking cam cover centre gaskets allowing oil to drown the plugs then try new coils.

 

[Sharpy1975]

Hey...thanks for the reply. 5 was replaced and one is now playing up.

I'll report back....all looked clean in the plug Wells.

 

[Sharpy1975]

OK....another coil seems to have sorted it. Is it good practice to change all along with spark plugs?

 

[Jameszy]

I'd be interested in knowing this too. I will be due a spark plug change next year, think I am on original coils after 93,000 miles.

 

[colb]

Not really necessary to change them all out at once if one or two have gone bad there may be lots of life left in the other ones. However having said that do you really want to strip the cam cover off again when the next one packs up? Given the age and mileage our cars have now the coils will have gone through loads of heat cycles which over time will have an affect on their internals that in the end will cause them to fail. For peace of mind you might consider replacing all 6 then you have a level playing field to go forward. My 2.5 with 93k on the clock still has original coils, if I get a failure I would consider changing all 6 and keeping the old ones that still work as spares in the garage. It all really depends how fat your wallet is at the time.
Just had a look at Carparts4less they do ERA Ignition coils for £14.47 each, may be cheaper if you use their discount code that appears at the top of their home page, today its MID20.

 

[ph001]

Not everyone agrees with me but I've always advocated changing all 6 if of same age. And your experience seems to back that up!

 

[Chris_D]

150k miles here on original coils.
Always carry a spare coil plus a new plug and tools in the boot, esp on long trips.
Won’t be replacing all 6 coils at once. False economy. Just record how many miles are on each and replace as required.